J . CHEM. SOC. DALTON TRANS. 1995 2397

Novel H eterot ri nuclear, PtAg,, and Hexanuclea r, Pt,Ag4, Compounds containing Bridging Alkynyl Groups. Crystal Structure of [ Pt,Ag,( C,F,),( p3-q2-C-CPh),( PPh3),].0.5CH2C12 t Irene Ara,a Juan Fornies,*rB Elena LaIinde8*sb M. Teresa Morenob and Milagros Tornasa a Departamento de Qulmica lnorganica, lnstituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza- Consejo Superior de In vestigaciones Cientlficas, 50009 Zaragoza, Spain

Universidad de La Rioja, Departamento de Qulinica, 26001 Logroiio, Spain

Treatment of the polymeric derivatives [{PtAg,(C,F,),(C=CR),},] ( R = Ph or Bu') with 2 molar equivalents of neutral ligands L (Ag : L 1 : 1 ) afforded the new more soluble trinuclear mixed-ligand complexes [PtAg2(C,F,),(C~CR),4] 1-8 (L = PPh,, PEt,, CNBu' or C,H,N). Analogous reactions with 1 molar equivalent of L (Ag: L 2 : l ) produced, however, only a partial depolymerization of [(PtAg,( C6F5),(C=CR),},] to give the hexanuclear complexes [Pt,Ag,(C6F,),(C~CR),LZ] 9-1 6. Compounds 9-1 2 have also been obtained by treatment of the binuclear derivatives [NBu,] [Pt(C6F5),(p-C~CR),AgL] with AgCIO, (1 : 1 molar ratio) in acetone. Similar reactions of [(PtAg,(C,F,),(C~CR)~},] with 1 or 0.5 equivalent of 1.2- bis(dipheny1phosphino)ethane (dppe) yielded insoluble complexes of composition [ { P ~ A ~ , ( C , F , > , ( C Z C R ) , ( ~ ~ ~ ~ ) } ~ ] 17, 18 or [{Pt,Ag,(C,F,),- (C=CR),(dppe)},] 19, 20 which are thought t o be polymeric. The crystal structure of [Pt,Ag,(C,F,),- (p3-q2-CrCPh),( PPh3),]-0.5CH,CI, 9*0.5CH2CI, has been determined by X-ray diffraction methods.

The chemistry of metal alkynyl complexes has undergone important development in recent years.' The interest in this area is due both to the versatile reactivity of the acetylenic fragment, which has been used for the generation of other hydrocarbyl ligands, and to the ability of the alkynyl groups to bond to transition metals displaying a great variety of bonding modes.

Recent efforts in our group have been focused on the synthesis of homo- and hetero-polynuclear complexes of platinum in which the metal centres are linked only by alkynyl groups. Thus, we have previously reported the preparation of several hexanuclear [Pt,M,(C=CR),] (M = Ag, Cu or Au), and tetranuclear Q,[Pt,M,(C,F,),(C-CR),] (Q = PMePh, or NBu,, M = Ag or Cu, R = Ph or Bu') complexes by treating the homoleptic [Pt(CSR),I2 - or mixed-ligand cis- [Pt(C6F,)2(C-CR)2]2- o-alkynyl substrates with adequate transition-metal Lewis acids. The tetranuclear complexes [NBu,]2[Pt,Ag2(C,F,)4(C~R)4] also react with neutral ligands to give binuclear [NBu,][(C,F,),Pt(p-C~R),AgL] or tetranuclear [NBu,] , [ ((C,F,),Pt(~-C~CR),Ag} ,(p-dppe)] (dppe = Ph,PCH,CH,PPh,) anionic complexes, depending on the ligand used.* Stable trinuclear [Pt(CSPh),(MX),]'- (M = Cu or Ag; X = C1 or Br) or hexanuclear [Pt,M,- (C-CBu'),X212 dianionic species can also be obtained by treatment of [Pt2M4(C=CR)J with NBu,X, albeit the similar reactions with phosphine ligands L (PPh, or PEt,) result in precipitation of the polymeric acetylides M C K R (Cu or Ag) and formation of tran~-[Pt(C=CR),L,1.~ The structures of some of the resulting complexes have revealed that the strength and the asymmetry of the silver-alkyne q linkages are strongly dependent on the presence or absence of other ligands on the silver centre.

Recently we reported the synthesis of polynuclear complexes [(PtAg2(C,F,)2(C=CR),},] (R = Ph or But) which, due to their low solubility in common non-donor solvents, were thought to display a polymeric structure, probably based on

t Supplementary dutu available: see Instructions for Authors, J. Chem. Soc., Dalton Truns., 1995, Issue 1, pp. xxv-xxx.

square-planar CiS-Pt(C,F5),(CeR)2 fragments connected by Ag atoms q2 bonded to acetylide groups (Scheme 1, A).6 We observed that only the tert-butylacetylide derivative reacts readily in acetone yielding the more soluble hexanuclear species [Pt2Ag,(C,F,)4(C~CBut)4(Me2~~)4],6 the molecular struc- ture of which shows it to be formed by two identical binuclear fragments[(C,F5),Pt(~-CSBu1)~Ag(Me2CO)2]linkedthrough two silver atoms (B), with the alkynyl groups acting as p3-q2 bridging ligands. These findings prompted us to investigate the reactivity of the yellow polymeric material [(PtAg,(C,F,),- (CSR),),] (R = Ph or But) towards other compounds in order to analyse the influence of the R group on the reactivity and on the stability of the polynuclear derivatives when formed. In this paper we present the results of the reactions between [{PtAg,(C,F5),(C~R),},] (R = Ph or Bu') and neutral donor ligands [L = PPh,, PEt,, CNBu' or pyridine (py)] using two different molar ratios 1 : 2 (Ag: L 1 : 1) and 1 : 1 (Ag: L 2: l ) , which afford, respectively, two new types of polynuclear neutral complexes: (a) trinuclear [PtAg, (c, F5)2 - (C=CR),L,] derivatives and (b) hexanuclear [Pt2Ag,(C6F5),- (C=CR),L,] compounds. The reactivity of the polynuclear complexes with 1,2-bis(diphenylphosphino)ethane and Br- has also been studied, and the results are reported. Part of these results have been published as a preliminary communication.'

Results and Discussion The results of the reactions starting from [(PtAg,(C,F,),- (C=CR),}J are summarized in Scheme 2. Addition of 2 equivalents of neutral ligands (Ag: L 1 : 1) to a yellow (for R = Ph) or white (R = But) suspension of [(PtAg,(C,F,),(Cr CR),},] in acetone gave a clear solution, from which neutral trinuclear alkynyl bridged complexes [PtAg,( C6F5)2 (C~ CR),L,] 1-8 can be isolated as yellow (R = Ph) or white (R = But) microcrystalline solids [Scheme 2(i)]. In contrast with the dimeric nature found for [{ PtAg,(C,F,),(CSBu'),- (Me,CO),},] (Scheme 1, B), analytical and molecular weight determinations (Table 1) indicate that complexes 1-8 are formed by monomeric [PtAg,(C,F,),(C~R)~L,] units, which

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2398

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J . CHEM. SOC. DALTON TRANS. 1995

suggests that, with stronger ligands (PPh,, PEt,, CNBu' or py), the polymeric derivatives are cleaved into the more soluble trinuclear species [PtAg,(C,F,),(C&R),L2]. This fact has been confirmed by a single-crystal X-ray study of

Me \

but n

B

Scheme 1 (i) Acetone; (ii) air dried

[ PtAg,(C, F5)2( CZPh),( PPh ,),I 1 which has been previously communicated.

On the other hand, when complexes [{PtAg,(C,F,),- (CzCR),},] are treated with only 1 equivalent of neutral lig- ands [Scheme 2(ii), see Experimental section] (Ag:L 2 : 1) a partial depolymerization takes place, yielding the hexanuclear tetraal kynyl complexes [Pt 2Ag4(C6F ,),(C=CR),L,] 9-1 6 as yellow (R = Ph 9, 11, 13 and 15) or white (10, 12, 14 and 16) solids in good yields. Complexes 9-12 (L = PPh, or PEt,) can be prepared equally well from the binuclear doubly acetylide bridged (o-Pt, n-Ag) [NBu,][Pt(C,F,),(p-CzCR),AgL] and AgClO, [I : 1; Scheme 2(iii)] in acetone; under these conditions the sparingly soluble derivatives 9-1 1 precipitate immediately. As expected, the trinuclear complexes 1-4 can also be obtained stepwise from the hexanuclear derivatives 9-12. Thus, the addition of an excess of PPh, or PEt, [ratio 2: 1; Scheme 2(iv)] to a suspension of the dimeric derivatives 9-12 (solution for 11) affords yellow (9 and 11) or colourless (10 and 12) solutions from which the corresponding monomeric trinuclear species [PtAg2(C,FS),(C=CR),L2]'(L = PPh, 1 or 2, PEt, 3 or 4) can be isolated. All these facts, together with satisfactory molecular- weight determinations for 11 and 14, suggest that complexes 9- 16 are probably hexanuclear species formed by two anionic [Pt(C,F,),(p-C=cR),AgL] - units joined together through the two additional silver cations. Final proof of their hexanuclear nature is provided by the crystal structure of 9, which is discussed later. Attempts to obtain anionic complexes related to 9-16, but with the neutral ligand replaced by an anion (Br-), were unsuccessful. Thus, when the polynuclear derivatives [{PtAg2(C6F,)2(C=cR),},] are treated with 1 equivalent of NBu,Br (Ag: Br- 2 : 1) in acetone [Scheme 2(uii)] a precipitate (AgBr) is formed and, after filtration, the tetranuclear derivatives [NBu,]~[P~~A~,(C~F,),(C=CR)~] are isolated from the mother-liquors and identified by usual methods.

Finally, we have explored the reactivity of [(PtAg2(C6F5)2-

(iv 1 3R2Ag4(C6F5)4(C ~ R ) ~ L z I n(PtAg2(C6F5)2(C=CR)2L21

L = PPh, (R = Ph 9 or But lo), PEt3 (R = Ph 11 or But 12), L = PPh? (R = Ph 1 or Bu'~), PEt, (R = Ph 3 or But 4), CNBU' (R = Ph 5 or But 6) or py (R = Ph 7 or But 8) CNBU' (R = Ph 13 or But 14) or py (R = Ph 15 or But 16)

R R = Ph 17 or But 18 R = Ph 19 or But 20

Scheme 2 acetone; (vi) + dppe (molar ratio 1 :0.5), acetone; (vii) + NBu,Br (molar ratio 1 : 1 )

(i) + L (molar ratio 1 :2); (ii) + L (molar ratio 1 : 1); (iii) + AgCIO, (ratio 1 : I ) , acetone; (iu) as (i); (0) + dppe (molar ratio 1 : l),

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Tabl

e 1

Elem

enta

l ana

lyse

s, yi

elds

, mol

ecul

ar w

eigh

ts a

nd re

leva

nt I

R a

bsor

ptio

ns fo

r com

plex

es 1

-20

Ana

lysi

s (%

)' IR

(cm

-')

C

52.4

0 (5

2.20

) 50

.35

(50.

35)

40.7

5 (4

0.60

) 37

.85

(37.

80)

40.2

5 (4

1 .OO

) 37

.75

(38.

05)

41.3

5 (4

1.30

) 37

.89

(38.

33)

45.8

5 (4

5.70

) 43

.00

(43.

15)

38.4

0 (3

8.35

) 34

.60

(35.

15)

38.6

5 (3

8.50

) 34

.85

(35.

15)

38.9

0 (3

8.60

) 35

.20

(35.

30)

48.5

5 (4

8.15

) 46

. I5

(46.

00)

42.8

5 (4

2.95

) 40

.40

(40.

15)

H

2.95

(2.7

5)

3.65

(3.4

0)

3.70

(3.4

0)

4.60

(4.2

5)

2.45

(2.5

5)

3.05

(3.4

0)

2.05

(1 3

0)

2.45

(2.6

5)

2.30

(2.1

0)

3.00

(2.8

5)

2.45

(2.3

5)

3.45

(3.2

5)

1.40

(1 3

5)

2.75

(2.7

5)

1.10

(1.5

0)

2.10

(2.3

0)

2.75

(2.5

5)

2.95

(3.2

5)

I .90

(1.9

5)

2.45

(2.7

5)

N -

-

-

-

2.30

(2.5

0)

2.55

(2.6

0)

2.55

(2.5

5)

2.51

(2.6

5)

-

-

-

-

1.55

(1.3

5)

1.45

(1.4

0)

1.20

(1.3

5)

1.30

(1.4

0)

-

-

-

-

Mu

.b

1567

(147

2)

1529

(143

2)

1264

(1 18

4)

1274

(1 1

44)

c 1122

(110

5)

d d 2014

(213

1)

d d 1966

(1 98

0)

d d d d

Yie

ld (%

) 61

87

70

75

75

68

71

84

87

90

37

75

83

73

64

73

86

75

88

80

V(C=

c) v(

CEN

) 20

51m

, 203

3 (s

h)

2040

m

2039

s 20

48m

20

38s

22 1 2

vs

2036

m

2191

vs

2032

m

2026

w

2021

m

2022

m

2026

m

2023

m

2032

w, 2

017w

22

14vs

20

1 ow

22

14vs

20

28m

20

06m

20

66m

, 203

4m

2037

w

2026

w

20 19

w

v(X

-sen

sitiv

e C6F

5)

799s

, 790

(sh)

79

3s, 7

84s

8OOs

, 779

s 79

3s, 7

84s

799v

s, 77

8s

793v

s, 78

5 (s

h)

797s

, 790

(sh)

79

5s, 7

86s

799v

s, 79

0 (s

h)

798v

s, 78

9vs

799v

s, 79

2 (s

h)

796v

s, 78

9 (s

h)

799v

s, 79

1 (s

h)

795v

s, 79

0 (s

h)

795v

s, 78

0 (s

h)

795v

s, 78

1 (s

h)

799v

s (sh

) 79

3s, 7

85s

801w

, 798

(sh)

79

6vs,

788

(sh)

Cal

cula

ted

valu

es in

par

enth

eses

. In

CH

CI,

solu

tion.

D

ecom

posi

tion

in C

HC

I, pr

eclu

des

mol

ecul

ar w

eigh

t det

erm

inat

ion.

N

ot s

olub

le en

ough

in C

HC

I,.

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2400 J. CHEM. SOC. DALTON TRANS. 1995

(GCR),},] towards the didentate ligand dppe in similar molar ratios [ i e . 1 : l (Ag:L-L 2 : l ) and 2 : l (Ag:L-L 4:1)]. Treatment of [{PtAg,(C,F,),(C=cR),),] with 1 or 0.5 equivalent of dppe affords yellow (R = Ph) or white (R = But) solids, which analyse as [{PtAg2(C,F,),(C=CR),(dppe)},] (R = Ph 17 or Bu' 18) or [{Pt,Ag4(C6F,)4(c~R)4- (dppe)),] (R = Ph 19 or Bu' 20), respectively. The insolubility of these complexes has precluded molecular weight determin- ations or the use of some identification techniques (NMR spectroscopy). We suggest that the insolubility of 17 and 18 may be due to their polymeric structure [{cis-(C6F5),Pt- (p3-q2-C=CR)2Ag2),(p-dppe),], based on mononuclear anionic Cis-Pt(C,F,),(C=CR), units linked by dicationic fragments Ag(p-dppe)Ag through silver-acetylide IT linkages as shown in Scheme 2. In the case of 19 and 20, a similar polymeric structure [{ Pt2Ag4(c6F5)4(p3-~2-C=CR)4),(p-dppe)n], based on tetranu- clear dianionic [Pt,Ag,(C6F,),(p3-q2-C~R)4]2 - units joined by Ag(p-dppe)Ag fragments (see Scheme 2), can be achieved. Probably, as is observed for the hexanuclear derivative 9, the alkynyl groups in these complexes 17-20 are acting as p3-q2 (G-

Pt, K , IT-A~,) bridging ligands.

Crystal Structure of [Pt2Ag4(C6F5)4(p3-q2-czcPh)4- (PPh3),]~0.5CH,Cl, 9.0.5CH2C1,.-Suitable crystals of com- plex 9*0.5CH,C12 were obtained by slow diffusion at -40 "C of hexane into a dichloromethane solution of the complex. The crystal structure reveals that this compound crystallizes with two crystallographically independent, but chemically very similar, hexanuclear [Pt2Ag4(C6F,),(CrCPh),(PPh3),] mol- ecules in the asymmetric unit. Discussion of the structure will therefore be limited to only one of the molecules. The complete molecular structure of 9 is shown in Fig. 1. Selected bond distances and angles are listed in Table 2.

The skeleton of complex 9, which posesses an inversion centre, is similar to that previously found for the hexanuclear complex [Pt ,Ag,(C,F,)4(C~Bu')4(Me2~~)4] (Scheme 1, B). Complex 9 consists of two identical units cis- (C,F,),Pt( I)(p-C=CPh),Ag( I)(PPh,) joined together by two silver atoms CAg(2) and Ag(2a)l through bridging C&Ph groups. Therefore, there are two different types of silver atoms (terminal and bridging) in the molecule. Each unit consists of cis-Pt(C,F,),(C=CPh), and Ag( l)PPh3 fragments bonded through the two alkynyl functions. The platinum atom Pt( 1) is located in an approximately square-planar environment formed

by four C atoms (the two Cipso of the two C,F, cis and the two C, of the two C,=C,Ph ligands), the Pt( 1)-C distances (to C,F, or C g P h groups) being similar to those found in other related c o m p l e ~ e s . ~ * ~ * ~ The silver atom Ag( l), located 1.340( 1) A down from the Pt(1) co-ordination plane, is in an approximately trigonal environment formed by the phosphorus atom, the midpoint of one of the acetylenic fragments [C(21)&(22)] and the C, atom of the second alkynyl function C(13)-C(14). The Ag(1) C( 14) distance is extremely long [2.875(16) A], which suggests that the interaction of Ag(1) with the C, atom of the acetylenic fragment C( 13)-C( 14) is negligible. The Ag( 1)-P( 1) bond length [2.395(4) A] falls in the range of values found for other polynuclear complexes containing the Ag(PPh3) unit 4*8

and the Pt(1) Ag(1) distance [3.066(1) A] is out of the range of values reported for Pt-Ag bond

Both square-planar platinum environments are parallel and interconnected by the bridging silver atoms CAg(2) and Ag(2a)l forming the hexanuclear molecule. The silver bridging atoms CAg(2) and Ag(2a)l are unsymmetrically bonded to two alkynyl functions, one associated with each Pt atom, the acetylenic bonds being perpendicular to one another. Thus, Ag(2) is unsymmetrically bonded to both atoms C, and C, of the C(13)-C(14) alkynyl ligand at Pt(l), but only to C, of the C(21a)-C(22a) group at Pt(1a). The Ag(2) C(22a) distance of 2.812(16) A is well beyond the normal bonding range, suggesting again that the interaction with this C, atom is negligible. The distances of this Ag(2) atom to both platinum atoms are different. The shortest Ag(2) Pt(1a) bond length [2.888(2) A] associated with the small Ag(2)-C(21a)-Pt(la) angle of 83.6(4)' suggests a weak Pt-Ag interaction.' However, the Ag(2)-C( 13)-Pt( 1) angle is 91.5(5)" and the resulting Ag(2) Pt( 1) distance is 3.105(2) A, excluding any bonding interaction between these metals.

It is interesting that one of the two C,F, groups associated with each platinum atom [C(7),,,, at Pt(l), see Fig. 1) is so positioned that one o-fluorine atom makes a short contact with each one of the silver bridging centres. The o-F(8) Ag(2) distance [2.790(12) A] falls in the range of distances found for similar o-F Ag contacts in other (pentafluoropheny1)- platinum silver complexes,' implying a donation of elec- tron density to the silver atom. This contact and the Ag(2) Pt(1a) interaction are probably accentuating the unsymmetric co-ordination of the alkynyl groups. Considering the o-F Ag and the Pt( 1 a) Ag(2) interactions and also

Table 2 Selected interatomic distances (A) and angles (") for [Pt2Ag,(C6F5),(C-=CPh),(PPh3),1.0.5CH2Cl2

3.066( 1) 2.053( 12) 2.042( 14) 2.395(4) 2.568( 13) 2.68(2) 2.888( 2) 2.274( 1 1 ) 1.18(2)

84.08(4) 91.5(5) 93.6(5)

177.7( 12) 85.5( 5)

170.4( 12) 83.6( 5)

I72.28( 10) 91.5(5) 8 7.9( 5)

172(2)

3.105(2) 2.048( 13) 2.05(2) 2.454( 13) 2.354( 12) 2.285( 1 1) 2.959( 2) 1.24(2) 2.790( 12)

86.6(5) 88.4(5)

142.1(4) 1 15.9(3) 138.8(3) 88.3(9)

104.3(10) 92.2( 10) 96.6( 10)

175(2)

Symmetry transformation used to generate equivalent atoms: - x , - y , --z - 1.

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ci291

Fig. I Molecular structure of [Pt,Ag4(C6F5)4(p3-q2-CzCPh)4- (PPh,),] 9 showing the atom numbering scheme. Phenyl rings (except Cipso atoms) of the PPh, ligands and the C(2)-C(6) and C(2a)-C(6a) C,F, rings have been omitted for clarity. Symmetry transformation to generate equivalent atoms 'a': -x , --y, - z - 1

the bonds to the two alkynyl functions, each silver bridging atom seems to be located in a distorted-tetrahedral environment (Fig. 1).

The co-ordination mode of the alkynyl ligands can be described as a very unsymmetric p3-q2. In fact, the C(21)-C(22)-Ph fragment is clearly CT bonded to Pt(1) [Pt(l)-C(21) 2.05(2) A] and CT bonded as well to Ag(2a) [Ag( 2a)-C( 2 1 ) 2.274( 1 1 ) A, Ag( 2a) C( 22) 2.8 12( 16)A], while the interaction with Ag(1) [Ag(l)-C(21) 2.354(12) A, Ag(1)- C(22) 2.68(2) A] seems to display a higher side-on character, the Ag-C(2 1 ) interaction being predominant. The other alkynyl ligand C(13)&(14)-Ph is bonded to the metal centres in a similar way, and displays two o-C-M bonds [Pt(l)-C(13)

A] while the interactions with Ag(2) show more x character [Ag(2)-C( 13) 2.285( 1 1) A, Ag(2)-C( 14) 2.568( 13) A]. All these structural facts suggest that the silver centres prefer bonding to the C, atoms, which have higher electron density, and that the co-ordination mode of the alkynyl ligands is approximately halfway between the normal p3-q2 manner and the p3-q' bridging mode. As a consequence, the alkynyl bending of the CZCPh fragments is negligible (see Table 2) and significantly smaller than the bending found in symmetrical p3-q2 alkynyl bridges.

The molecular structure of [PtAg2(C,F,)2(CrCPh)2(PPh3)2] 1 has been reported previ~us ly .~ The most remarkable structural features are: (a) the significant asymmetry of the whole molecule; (b) one of the Ag(PPh,) units is bonded to the two alkynyl functions, while the second unit seems to be bonded to the platinum atom and only to one alkynyl group and (c) one of the alkynyl fragments is acting as a p-q2(o-n) ligand and the other bridges the three metal atoms in a predominantly CJ

manner ( ~ ~ - q l ) . ~

2.042( 14)& Ag( 1)-C( 13)2.454( 13)A,Ag( 1) C( 14)2.875( 16)

Infrared and N M R Spectra.-Selected IR absorptions are collected in Table 1 . All complexes show one (or two in the cases of 13 and 17) v(Cd2) vibration in the expected region (2006 2066 cm-') for bridging alkynyl l i g a n d ~ ~ - ~ and two IR absorptions corresponding to the X-sensitive mode of the pentafluorophenyl ligands in the 801 -778 cm-' region, indicative of a cis disposition of C,F, group^.^*^*^.'^ Th e adducts with tert-butyl isocyanide ( 5 6 and 13, 14) exhibit also

a strong, slightly broad band at 2191-2214 cm ' assignable to the v(C=N) stretching vibration of terminal CNBu' ligands.

The NMR data for complexes 3-16 are given in Table 3. The room-temperature 'H NMR spectra exhibit resonances due to the ligands (L) and the signals of the alkynyl groups (R = Ph or But) in the expected integration ratio. The complexes with R = But show only one single resonance for the methyl groups of the C S B u ' ligands, thus indicating that, in solution, all CKBu ' groups are equivalent.

The 31P-{1H) NMR spectra of the hexanuclear derivatives 9- 12 at room temperature show the characteristic pattern of a pair of doublets, due to coupling of 31P to both lo7Ag and '09Ag isotopes, indicating that both phosphine ligands are equivalent and that the Ag-P bonds are retained in solution. '

The 19F NMR spectra of the hexanuclear species are very similar and temperature dependent. At high temperature (50"C), or even at room temperature in the case of complex 15, they show only a set of three signals (ratio 2: 1 :2) corresponding to o-, p- a rn-F, showing that all C,F, groups

(doublet or singlet) to low field along with the expected platinum satellites, indicating an effective equivalence of these atoms. Formal equivalence of the rn-fluorine atoms, which appear as a multiplet at high field, is also observed. The o- fluorine signals broaden as the temperature is lowered and at - 50 "C clearly split into two sharper resonances, each with the expected 19,Pt satellites (for 15 only two broad o-F resonances are observed). The rn-fluorine signals also broaden when the system is cooled and for complexes 11, 13, 14 and 16 are also split into two different resonances at - 50 "C. The presence of two different o- (and rn-) fluorine environments at low temperature is consistent with stereochemically rigid molecules for which the co-ordination planes of the platinum centres are not symmetry planes. The observed pattern at high temperature is typical of AA'MXX' systems for which the co-ordination planes of the platinum centres are formal (time-averaged) symmetry planes.

The unsymmetric co-ordination of the two Ag(PEt,) fragments in the trinuclear derivatives 3 and 4 is not observed in solution. Thus, the room-temperature 31P NMR spectrum of complex 4 exhibits a pair of doublets centred at 6 7.3, which are best resolved at low temperature [ - 50 "C, 6(P) 6.5; 'J('09Ag-P) = 699, J(lo7Ag-P) = 6051 indicating that, in solution, the PEt, ligands are equivalent. For the analogous derivative 3 (R = Ph, L = PEt,), the separate splitting due to the two isotopes of silver is not resolved at room temperature; the ,'P spectrum exhibits a broad doublet centred at 6 9.9 with a spacing of 667 Hz. However, at low temperature (- 50 "C) the pair of doublets [6(P) 9.1; 'J('09Ag-P) = 715 and ' J - (Io7Ag-P) = 621 Hz] is clearly resolved. The I9F NMR spectra of both complexes 3 and 4 (Table 3) show three sharp signals (ratio 2 : 1 : 2) corresponding to a single set of Fo,oe, F, and F,,,,,,, indicating that in solution the C,F, groups are equivalent. The 19F NMR spectrum of complex 3 at - 50 "C shows the same sharp pattern as that at room temperature. These spectral patterns suggest that, even at low temperature, the platinum co- ordination plane and also the PtAg, plane are formal planes of symmetry in both complexes.

The 'H NMR spectra of the isocyanide (5, 6) and pyridine adducts (7, 8) are not temperature dependent. At room temperature these adducts display only one signal pattern for both the C S R groups and the CNBu' or py ligands (see Table 3). By contrast, their 19F NMR spectra are temperature dependent. Thus, at high temperature (50 "C) the spectra display a group of three sharp signals (for 6 and 8 the o-F resonances are broad) in a 2 : 1 : 2 ratio corresponding to a single set of 0-, p- and m-fluorine atoms. When the solutions are cooled to room temperature the p-fluorine resonances remain sharp but the o-fluorine signals broaden, in the case of 5 and 7, or decoalesce into two broad resonances for 6 and 8. On further cooling to - 50 "C the broad signal for 7 was resolved into two

are equivalent. The o-fluori TI e atoms occur as a sharp resonance

Publ

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1995

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Tabl

e 3

Fluo

rine-

19,

31P a

nd 'H

NM

R d

ata"

for c

ompl

exes

1-1

6

I9F

3'

P 'H

Com

pd.

T/T

1

25

2 25

-

60

3 20

- 50

4

20

- 50

5c

.d 50

20

6

50

20

- 50

7*

50

20

- 60

- 50

8

50

20

- 50

9

50

20

- 50

10

50

20

- 50

11

50

25

12

50

25

- 50

13

50

20

-

50

14

50

20

- 50

I5

20

- 50

16

50

20

- 50

- 50

W,)

- 1

17.9

(d, 3

99)

- 1

17.9

(d, 4

08)

- 11

7.5 (

d, 40

2)

- 1

18.4

(d, 3

90)

- 11

4.4

(d, 3

83)

- 1

14.3

(br)

' - 1

13.8

(s, b

r)'

-112

.5,

-115

.3/

-111

.4(~

,444

), -1

16.1

(s

, br)

'

- 11

5.5 (

s, br

, 361

)

-113

.0(s

, br

,451

), -

117.

8(s.

br,

333)

-1

15.3

(s

, br)

' z -

114,

-1

16/

- 11

5.6 (

d, 39

7)

-112

.7(d

,456

),

-118

.1

(dd,

364)

- 1

15.7

(d, 4

04)

- 1

15.6

(s, b

r)'

- 1

12.6

(d, 4

59). - 1

17.9

(d, 3

63)

-115

.1 (

~,4

15)

- 1

14.9

(s, v

br)'

-113

.3 (

d,44

8), -

117.

1 (d

, 364

) - 1

1 5.6

(d, 3

64)

- 1

12.6

(d, 3

36), - 1

18.1

(d, 3

43)

- 11

5.2 (

s, 3

65)

-115

.4'

- 11

2.9 (

s, 42

3), -

117.

8 (s

, 402

) - 1

1 5.2

(d, 4

1 1)

- 11

5.2'

- 11

2.6 (

d, ~

44

0),

- 1

18.0

(d, 3

30)

-115

.9(b

r)'

- 11

4.4 (

s, b

r)'

- 11

2.9,

- I 1

6.3/

- 11

2.0 (

d, 44

1), - 1

17.7

(d, 3

57)

- 11

4.0 (

d, 41

0)

z -

108,

-1

12/

- 11

5.4 (

s, b

r)'

- 1

15.5

' - 1

13.1

(d, 4

50), -

1 18.

4 (d,

348

)

W,)

W

,)

- 1

65.5

(t) - 1

66.8

(m)

- 1

66.7

(tj - 1

67.8

(m)

- 16

5.2 (

t) -

166

.3 (m

)

- 1

67.0

(t) - 1

67.9

(m)

- 1

64.2

(t)

- 16

5.5 (

m)

-164

.1

(t)

-165

.4(m

) - 16

4.9 (

t) - 1

65.3

(m)

- 1

65.4

(tj - 1

66.6

(m)

- 1

64.9

(tj - 1

65.9

(m)

- 16

3.0 (

t) -

164

.6 (m

) - 16

3.1 (

t) - 1

64.7

(m)

- 16

2.8

(t) - 1

64.1

(m),

- 1

64.4

(m)

- 1

63.6

(t) - 16

5.2

(s, b

r)

-163

.1

(t)

-164

.1

(m),

-165

.1

(m)

- 16

3.4

(t) - 1

65.0

(m)

- 16

3.1 (

t) -

164

.8 (m

) - 16

2.5 (

t) - 1

64.1

(s, b

r)

- 1

64.0

(t) - 16

5.6

(m)

- 16

3.9 (

t) -

165.

4 (m

) - 16

3.3 (

t) - 1

65.0

(m)

- 16

3.2 (

t) - 1

65.0

(m)

- 1

63.0

(t) - 16

4.8

(m)

- 16

4.2 (

t) -

165

.8 (m

) - 16

4.0

(t) - 1

65.6

(m)

-163

.4(t

) -1

65.1

(m

) - 1

63.2

(t) - 16

4.8

(m)

- 1

63.0

(t) - 1

64.6

(m)

- 16

1.9 (

t) -

163

.1 (m

). - 1

63.3

(m)

- 16

3.7 (

t) - 1

65.2

(s)

- 1

62.3

(t) - 16

3.8

(s), - 1

64.4

(s)

- 16

4.2 (

t) - 1

65.7

(m)

- 16

3.7 (

t) - 16

5.3

(m)

- 16

4.5 (

t) - 1

65.4

(m)

- 1

62.9

(s) - 1

64.0

(s), -

- 15

9.8 (

t)

- 16

3.5 (

t) -

160

.6 (s

) - 1

65.1

(s)

- 16

3.2 (

t) -

164

.8 (s

, br)

- 1

62.5

(t) - 1

63.5

(m),

-

65.2

(s)

164.

6 (m

j

6(P)

14

.1

14.2

8 12

.5

12.9

5 9.

9 9.

1 7.

3 6.

5

701,

610

667

715,

621

694,

610

699,

605

14.7

8 72

7, 6

30

14.9

72

8, 6

30

11.3

73

2,63

5

5.64

73

6, 6

38

R L

0.86

(s) (

Bu'

)

7.21

(m),

7.31

(m) (

Ph)

1.20

(s, B

u')

7.44

, 7.6

(m, P

h)

1.65

(m, C

H,),

1.1

2 [d

, t, 3

J(P-

H)

= 1

8.5,

CH

,]

1.78

(m, C

H,),

1.2

6 [d

, t, 3

J(P-

H)

= 1

8.4,

CH

,]

7.21

(m),

7.36

(m) (

Ph)

1.40

(s, C

NB

u')

I. 13

(s, C

SB

u')

1.53

(s, C

NB

u')

1.1 (

s, C

gBu'

) 1.

51 (s

,CN

Bu'

)

7.26

7.0

3 (m

, 8.

38 [d

, H,,

py, J

(H-H

) =

4.4

1, 7

.7 (t

, H,,

py)

over

lapp

ing,

Ph,

py)

0.99

(s, B

u')

9.04

[d, H

,, py

, J(H

-H)

= 4

.21,

8.7

3 (t

, H,,

pyj,

7.45

(m, H

,, py

)

0.90

(s, B

u')

7.66

(m, P

h), 7

.52

(m, P

h)

7.45

(m, P

h), 7

.26

(m, P

h)

1.42

(m, C

H,)

, 0.9

2 [d

, t, ,

J(P-

H)

= 1

9, C

H,]

1.86

(m, C

H,),

1.3

0 [d

, t, '

J(P-

H)

= 1

8.3,

CH

,] 1.

18 (s

, Bu'

)

7.24

(m, P

h), 7

.36

(m, P

h)

1.37

(s. C

NB

u')

8.76

Cd,

H,,

py, J

(H-H

) =

4.7

1, 7

.95

(t, H

,, py

), 7.

57 (m

, H,,

py)

1.02

(s, B

u')

In C

DC

I,, c

hem

ical

shi

fts a

re re

porte

d re

lativ

e to

CFC

l3, H

3P0,

(85

%) a

nd S

iMe,

(as

exte

rnal

ref

eren

ces)

res

pect

ivel

y; c

oupl

ing

cons

tant

s J in

Hz.

3J

('95P

t-F,

)/H

z in

par

enth

eses

. A

t -5

0 "C

, the

I9F

NM

R s

pect

rum

of c

ompl

ex 5

sh

ows t

hree

sig

nals

in th

e o-

F re

gion

at 6

- 1

12.1

. - 1

15.2

and - 11

8.5 w

ith r

elat

ive

inte

nsiti

es 3

:2: 1

and

in t

hep-

and

m-F

regi

on a

com

plex

mul

tiple

t cen

tred

at 6

- 16

4.1.

A

t - 50

"C

, the

'H N

MR

spe

ctru

m e

xhib

its th

e sa

me

patte

rn a

s th

at o

bser

ved

at 2

0 "C

. ' Sa

telli

tes

are

obse

rved

but

the

3J('9

5Pt-

F,) i

s not

wel

l res

olve

d.

Two

broa

d hu

mps

. B

road

hum

p, p

latin

um s

atel

lites

are

not

obs

erve

d.

In C

D,C

OC

D,.

Publ

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1995

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J . CHEM. SOC. DALTON TRANS. 1995 2403

separate o-fluorine resonances and for 6 and 8 the two broad resonances became sharper. For complex 7 even the m-fluorine multiplet was resolved into two separate multiplets. For these derivatives probably a restricted rotation of the C,F, ring about the C-Pt bond causes the observed inequivalence in the fluorine atoms at low temperature.

Experiment a1 Elemental analyses were carried out with a Perkin-Elmer 240-B microanalyser. Infrared spectra were recorded on a Perkin- Elmer 883 spectrophotometer and NMR spectra with Varian XL-200 and Bruker ARX 300 spectrometers. The syntheses of [{ PtAg,(C,F,),(C~R),},,] (R = Ph or But) and [NBu,][Pt- (C,F,),(p-C=cR),AgL] (R = Ph or But, L = PPh, or PEt3)4 have been described previously. All reactions were carried out at room temperature with exclusion of light. CAUTION: Some of the following preparations use AgClO,, which is potentially explosive.

Syntheses. -[PtAg,(C,FS),(C=cR),L2] 1-7. Method 1. The stoichiometric amount of L (Pt : L 1 : 2; Ag : L 1 : 1) was added to a suspension of [(PtAg,(C6F5)2(C=cR)2]fl] (ca. 120 mg) in acetone (z 5 cm3), whereupon a solution (yellow for R = Ph 3, 5, 7 or colourless for R = But 4, 6) was formed. On evaporation to dryness, addition of EtOH ( ~ 5 cm3) and stirring, a solid (yellow 3,5 and 7 or white 4 and 6) was formed, which was washed with EtOH and air dried.

Method 2. The complexes [PtAg,(C,F,),(C=CR),L,] [L = PPh3' (R = Ph 1 or But 2) or PEt, (R = Ph 3 or But 4)] can also be prepared by treating the corresponding hexanuclear derivatives [Pt,Ag,(C6F5),(C~CR),L2] 9-12 with 2 additional equivalents of triphenylphosphine or triethylphosphine (Pt : L 1 : 1). A typical preparation (complex 3) was as follows: PEt, (13.4 pl, 0.091 mmol) was added to a yellow solution of [Pt2Ag4(C,F,),(C-=CPh)4(PEt,)2] 11 (0.097 g, 0.045 mmol) in acetone (10 cm3). The mixture was stirred for 20 min and then evaporated to dryness. Upon addition of ethanol (5 cm3) to the residue, complex 3 was obtained as a yellow solid (70% yield). Complexes 1, 2 and 4 were obtained similarly by using the appropriate starting material and phosphine. In all cases the yield was ~ 8 0 % . [P~A~,(C,F,),(C=CBU')~(~~)~] 8. A yellow suspension of

[{PtAg,(C6F,),(C~Bu'),),1 (0.100 g, 0.110 mmol) in CH,CI, (2 cm3) was treated with pyridine (0.778 cm3 of a solution 0.494 mol dm in CH,Cl,, 0.386 mmol) giving immediately a colourless solution. Hexane (20 cm3) was added and the mixture kept in a refrigerator overnight. The resulting white microcrystalline solid 8 was filtered off, washed with hexane and air dried.

[Pt2Ag,(C,F,),(C=CR)4L2] (L = PPh,, R = Ph 9 or But 10; L = PEt,, R = Ph 11 or But 12). Method 1. To a suspension of [(PtAg,(C,F,)2(C=CR)2}n] (ca. 120 mg, yellow R = Ph or colourless R = But) in acetone (ca. 10 cm3) was added the stoichiometric amount of phosphine (Pt:L 1 : 1) and the mix- ture was stirred for 1 h. For R = Ph, L = PEt,, the resulting yellow solution was evaporated to small volume (ca. 2 cm3) and EtOH was added to give complex 11 as a yellow solid, which was filtered off and air dried. For complexes 9 (yellow), 10 (white) and 12 (white) the solids formed were filtered off and air dried.

Method 2. Complexes 9-12 can also be prepared by treating the previously described binuclear derivatives [NBu,]- [Pt(C,F,),(p-C-CR),AgL] with AgClO,. A typical prepar- ation (complex 9) was as follows: AgC104 (20 mg, 0.095 mmol) was added to a colourless solution of [NBu,]- [Pt(C,F,),(p-C=CPh),Ag(PPh,)] (0.128 g, 0.095 mmol) in acetone. The solution immediately turned yellow and, after stirring for a few (ca. 5 ) minutes, a yellow solid precipitated. The mixture was stirred for 1 h and then the yellow solid formed (9) was filtered off (yield 83%). Complexes 10 and 12 were obtained

similarly by using the appropriate starting material. For complex 11 the resulting yellow solution was worked up in a similar way to the above general method. Yields: 10 (93), 11 (83) and 12 (90%). [Pt2Ag,(C6F5)4(C=CR)4(CNB~t)2] (R = Ph 13 or But 14).

A yellow suspension of [{PtAg,(C6F,),(C=cPh),},] (0.100 g, 0.106 mmol) in acetone (5 cm3) was treated with CNBu' (12 p1, 0.106 mmol) and the mixture stirred for 15 min. The resulting yellow solution was evaporated to dryness and the residue treated with EtOH (10 cm3) to give complex 13 as a yellow solid which was filtered off, washed with EtOH and air dried.

The stoichiometric amount of CNBu' (13 pl, 0.1 10 mmol) was added to a stirred white suspension of [(PtAg2(C6F5),- (C-=CBu'),},] (0.100 g, 0.110 mmol) in acetone ( 5 cm3) giving immediately a colourless solution. The mixture was stirred for 15 min, concentrated until the precipitation of complex 14 as a white solid and then hexane was added to complete the precipitation'. The product was filtered off, washed repeatedly with hexane and air dried. [Pt,Ag,(C6F,),(C=cR),(py)2] (R = Ph 15 or But 16). The

stoichiometric amount of pyridine (0.21 cm3, 0.496 mol drn-,, 0.106 mmol) was added to a yellow suspension of [{PtAg2(C,F,),(C=cPh),},] (0.100 g, 0.106 mmol) in acetone (3 cm3) and the mixture stirred for 15 min. The resulting turbid yellow solution was then filtered. Slow addition of hexane ( 5 cm3) caused the precipitation of an orange gelatinous solid. After being cooled in a freezer overnight, the resulting orange solid was filtered off, washed with hexane and air dried.

To a suspension of [{PtAg,(C,F,),(C~But),},] (0.10 g, 0.1 10 mmol) in CH,Cl, (3 cm3) was added pyridine (0.22 cm3, 0,110 mmol, 0.496 mol dm-3 solution in CH,Cl,). After being stirred for 15 min, the resulting colourless solution was filtered and mixed with hexane (20 cm3). The mixture was kept in a freezer (2 d) to render a white microcrystalline solid (16) which was filtered off, washed with hexane and air dried. [{PtAg2(C,F,),(C=CR),(dppe)},,] (R = Ph 17 or But 18).

1,2-Bis(diphenylphosphino)ethane (26 mg, 0.066 mmol for R = Ph or 44 mg, 0.110 mmol for R = But) was added to a suspension of [PtAg,(C,F,),(C=CR),] (R = Ph, 0.063 g, 0.066 mmol; R = But, 0.100 g, 0.110 mmol) in acetone (20 cm3). After being stirred for 1 h, the solution was filtered and concentrated to about 5 cm'. For R = Ph, the addition of ethanol ( ~ 2 cm3) gave a yellow precipitate (17) which was filtered off and washed with EtOH. For R = But, the resulting white precipitate (18) was filtered off, washed with acetone and air dried. [Pt,Ag,(C,F,),(C=CR),(dppe)] (R = Ph 19 or But 20). The

diphosphine dppe (25 mg, 0.062 mmol for R = Ph; 22 mg, 0.055 mmol for R = But) was added to a suspension of [{PtAg,(C,F,),(~R),),] (0.1 18 g, 0.124 mmol for R = Ph; 0.100 g, 0.1 10 mmol for R = But) in acetone (20 cm3). The mixture was stirred for 24 h and then the yellow (R = Ph 19) or white (R = But 20) solid formed was filtered off, washed with acetone and air dried.

Reactions with NBu,Br.-A suspension of [(PtAg,(C,F,),- (C-=CPh),},] (0.089 g, 0.094 mmol) or [(PtAg,(C,F,),- (CECBU'),},] (0.090 g, 0.100 mmol) in acetone (20 cm3) was treated with NBu,Br [31 mg, 0.094 mmol, R = Ph; or 32 mg, 0.100 mmol, R = But; molar ratio Pt: Br 1 : 13 giving immediately a slightly turbid solution. The mixture was stirred for 6 h and then filtered. Evaporation of the filtrate to a small volume (ca. 1 cm3) and addition of diethyl ether led to the precipitation of microcrystalline solids (yellow for R = Ph, white for R = But) which were filtered off and identified as the tetranuclear complexes [NBu,] , [P~,A~, (C,F, )~(C~R)~] by comparison of their spectroscopic data with those of authentic samples. Yields: 80% for R = Ph and 72% for R = But.

Crystal Structure Determination of [Pt2Ag,(C, F5)4- (C=CPh),(PPh3),]-0.5CH2C12 .-Crystal data. C9,, ,H5 1Ag4-

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1995

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2404 J. CHEM. SOC. DALTON TRANS. 1995

Atomic coordinates ( x lo4) for [Pt2Ag,(C,F,)4(C=CPh)4(PPh,),]-0.5CH,Cl,

'y

- 547( 1) 901(1) 696( 1 )

2005(2) - 1819(5) - 3577(6) - 4608(6) - 3875(6) - 2 128(5) - 339(9) -71 l(9) - 1297(7) - 1567(6) - 1209(6) - 1890(8) - 2286(8) - 321 2( 10) - 3743( 10) - 3365(9) - 2459(9) - 742(8) - 626( 1 1) - 8 13( 12)

-1116(10) - 1247(9) - 1069(8)

783(9) 1587(9) 2487(9) 3 104( 10) 3987( 14) 4276( 14) 3727( 15) 2788( 12) - 461(8) - 479( 10) - 604( 12) - 1310(16) - 1463(17) - 824( 18) - 130(17) -29(16) 2925(8) 3701 (1 0) 438 1 ( 10) 4269( 13) 3520( 12) 287 l(9) 1625(9) 901(11) 590( 12) 971 (1 3)

1659( 13) 1979( 10) 247 1 (1 1) 2353(23) 2697(24) 3 148(22) 3029( 24) 257 5(26) 2689( 5 1 ) 3224(33) 3500(33) 3625(50) 3004( 23)

Y - 780( 1)

31(1) - 660( 1)

- 2 1 6(6) 4 l(9)

- 194(10) - 667(7) - 896(6) - 1999(6) - 3552(6) -4455(5) -3751(5)

531(2)

- 2 176(5) - 577(8) - 327( 10) - 223( 1 1) - 327( 12) - 564( 1 1) - 686( 10) - 2003(8) - 241 2(9) -321 l(9) - 3653(9) - 33 12(8) - 25 12(9) - 1019(7) - 1193(9) - 1454( 10) - 875( 12) - 1054(19) - 1829(20) - 2460( 16) - 22 19( 13)

441(9) 1118(9) 1918(9) 2026( 13) 2786( 16) 335 1 ( 1 8) 3280( 16) 2520( 1 1) - 243(9) - 33( 10) - 667( 14) - 1470(13) - 165702) - 1036(9)

9 0 3 8) 1481(11) 181 3( 12) 1527( 13) 946( 12) 643( 10)

1390(9) 1524(22) 2 1 8 1 (22) 2762(20) 2796(22) 2088(27) 1289(49) 2041(31) 2576(30) 2582(48) 1959(21)

- 3730( 1) - 3229( 1) - 5053( 1) - 2685(2) - 2532(4) - 241 4(6) - 3397(6) - 4522(5) - 4669(4) - 4753( 5) - 4558(6) - 3276(5) - 221 3(4) - 2392(4) - 3625(6) - 3045(7) -2971(8) - 3457(9) - 40 12(8) - 4092( 7) - 3582(6) -4105(7) - 40 14(9) - 3370(9) - 2830(7) - 2930(7) - 3852(6) - 3926( 7) - 3952(8) -4176(9) - 4203( 13) - 395 1 (1 5) - 3721 ( I 3) - 3721( 1 1) - 3779(6) -3710(7) - 3547(8) - 3075( 1 1) -2919( 13) - 3237( 14) - 3667( 13) -3848(10) - 2359(6)

- 1895(9) - 1883(9) - 2096(9) - 2347(7) - 1940( 7) - 2007(9) - 1430(10) - 8 17(9)

-2159(9)

-733(9) - 1267( 7) - 3299(7) - 3990( 18) - 4527( 18) - 4334( 17) - 3653(20) -3113(22) - 3938(42) - 4446(25) - 3526(25) - 41 7 l(42) - 3064( 17)

X

- 4606( 1 ) - 641 9( 1) - 4508( 1 ) - 7757(2) - 2752( 5) -1131(5) - 845(5) - 2224( 6) - 3838(5) - 41 53(7) - 3479(8) - 3 1 26( 7) - 3377(7) -4019(6) - 3363(7) - 266 l(8) - 1830(8) - 1679(9) - 2378( 10) - 3 19 l(8) -4144(7) - 3978(9) -3642(11) - 3463( 1 1 ) - 3575(9) - 39 17(8) - 4964( 7) - 5084(8) - 5084(8) - 5599( 10) - 5590( 13) - 5046( 14) - 4530( 14) - 451 6( 10) - 5838(7) - 6593(7) - 7502(8) - 8 146(8) - 90 17( 10) - 9239( 12) - 8643( 13) -7765(11) -8585(8) - 87 1 5(9) - 9393( 10) - 9956( 1 1) - 9820( 1 1) -9144(10) - 8354(8) - 9248(9) -9655(11) - 9222( 13) - 8365( 13) - 7923( 11) - 7490(9) -7987(11) - 7777( 16) - 7039( 17) - 6533 16) - 6768( 10)

2638( 14) 1775(21) 3500(22) 2634(30)

Y - 3670( 1) - 2959( 1 ) - 4704( 1 ) - 2278(2) -4725(5) - 4340(5) -2738(6) - 1565(6) - 1929(5) - 5299(5) - 5491(7) -41 18(8) - 2588(7) - 2390(5) - 3335(8) - 39 16(8) - 3744(9) - 2933( 12) - 2333(9) - 2557(8) - 3837(9) - 4596( 10) -4710( 10) - 4028( 13) -3240(1l)

- 3369(7) - 3058(8) - 2579(9) - 2736( 1 1 ) - 2312( 13) - 1695(14) - 1517(12) - 1952(10) - 3958(7) - 4068(7) - 4093(9) - 4303(9) - 4274( 10) - 4029( 15) - 3790( 15) - 38 1 8( 1 2) - 1737(8) - 2062(9) -1715(10) - 1059(12) - 738( I 1) - 1082( 10) - 3036(8) -3163(9) - 37454 10) -4232(11) -41 14(10) - 3533(9) - 1519(8) - 1356(10) - 767( 1 1) - 337( 10) - 486( 12) - 1062( 10)

- 3 159(9)

3561( 13) 383 l(20) 4 124(2 1) 3563(34)

7

- 982( 1) -480(1)

- 124(2) - 726( 5)

490( 1 )

- 575(5) - 6 18(5) - 836(6) - 998( 5) - 1555(5) -2771(6) - 3872(5) -3671(5) - 2452( 5) - 868(6) -761(7) - 680(8) - 694(7) -813(8) - 896(7) - 1 944(6) - 2068(8) -2716(9) - 3235(8) - 3 I 50(7) -2516(7) - 60(6) 407(7) 925(7)

1537(9) 20 1 3(9) 1871( 11) 1277( 10) 809(9)

- 11 12(6) - 1 200(6) - 1361(7) - 830(8) - 101 l(10) - 1713(13) - 2238( 12) - 2062(8) - 770(7) - 131 l(7) - 1786(7) - 1715(10) - 1161(11) - 668(8)

540(7) 474( 8) 978( 10)

1 542( 10) 1603(9) I120(8) 320(7) 880( 8)

1175(9) 901(11) 368( 12) 62(9)

8904( 12) 7702( 17) 7886( 18) 8090(23)

CIF2,P,Pt2, M = 2461.315, triclinic, s ace group PI, a = 15.265(3), b = 16.866(4), c = 19.759(4) 1, a = 106.66(2), p = 86.48(2), y = 95.86(2)", U = 4843.65 A3, 2 = 2, D, = 1.688 g ~ m - ~ , h(Mo-Ka) = 0.710 73 A, F(OO0) = 2354.0, pale yellow

prismatic parallelepiped, dimensions 0.30 x 0.30 x 0.72 mm, ~(Mo-Kor) = 3.81 mm-'. The asymmetric unit contains two molecules, each with a centre of symmetry.

Data collection, structure analysis and reJinement. Data were

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J. CHEM. SOC. DALTON TRANS. 1995 2405

obtained by Crystalytics Co. (Lincoln, NE). A crystal was sealed into a thin-walled glass capillary with epoxy. Measurements were made on a four-circle Nicolet (Siemens) Autodiffractometer with graphite-monochromated Mo-Ka radiation. Data were collected at 20 k 1 "C using the a-scan technique with 28 ranging from 3 to 45.8". Of the 13 782 reflections collected 13 3 16 were unique (absorption correction, minimum and maximum transmissions factors = 0.732, 1 .OOO). The structure was solved by the Patterson methodI3 and refined by full-matrix least squares on F2 for all reflections (SHELXL 93). l4 Non-hydrogen atoms were refined anisotropi- cally, except for the C atoms corresponding to a phenyl ring disordered over two positions at 0.65 and 0.35 occupancy, respectively, with the common Cipso atom [C(41)-C(46) for one phenyl ring and C(41), C(42')-C(46') for the other], and three C atoms of a phenyl ring [C(25)-C(27)] which showed large thermal parameters, probably due to some static and/or dynamic disorder. Hydrogen atoms were located at fixed positions, with the isotropic parameter being 1.2 times larger than that of the corresponding C atom. Some residual electron density was modelled as interstitial solvent (0.5 molecule of CH,CI, per formula unit, with one of the C1 atoms disordered over two positions at half occupancy). The final wR, factor was 0.146 for all non-negative data (R, = 0.053 and wR, = 0.127 for 9240 reflections with F > 40FJ. The weighting scheme was w = I / O ~ ( F , ) ~ + (0.0754 P),, where P = [(Fo2, 0) + 2Fc2],,,/3. The highest residual peak of 1.22 e k3 is thought to belong to some additional disordered solvent.

All calculations were performed on a Local Area VAX cluster (VAX/VMS V5.5) with the Siemens SHELXTL PLUS and SHELXL 93 software packages. 3,14 Atomic coordinates are given in Table 4.

Additional material available from the Cambridge Crystallo- graphic Data Centre comprises H-atom coordinates, thermal parameters and remaining bond lengths and angles.

Acknowledgements We thank the Comision Interministerial de Ciencia y Tecnologia (Spain, Project PB 92-0364) for financial support.

References 1 R. Nast, Coord. Chem. Rev., 1982, 47, 89; A. J. Carty, Pure Appl.

Clem., 1982, 54, 11 3; M. I. Bruce, Pure Appl. Chem., 1986, 58,

553; 1990, 6, 1021; P. R. Raithby and M. J. Rosales, Adv. Znorg. Chem. Radiochem., 1985, 29, 169; E. Sappa, A. Tiripicchio and P. Braunstein, Coord. Chem. Rev., 1985, 65, 219; J. Holton, M. F. Lappert, R. Pearce and P. I. W. Yarrow, Chem. Rev., 1983, 83, 135; M. I. Bruce, Chem. Rev., 1991,91, 197.

2 J. Fornies, P. Espinet, M. Tomas, F. Martinez, E. Lalinde, M. T. Moreno, A. Ruiz and A. J. Welch, J. Chem. Soc., Dalton Trans., 1990,791.

3 P. Espinet, J. Fornies, F. Martinez, M. Sotes, E. Lalinde, M. T. Moreno, A. Ruiz and A. J. Welch, J. Organomet. Chem., 1991,403, 253.

4 J. Fornies, E. Lalinde, F. Martinez, M. T. Moreno and A. J. Welch, J. Organomet. Chem., 1993,455,271.

5 J. Fornies, E. Lalinde, A. Martin and M. T. Moreno, J. Organomet. Chem., 1995,490, 179.

6 J. Fornies, M. A. Gomez-Saso, F. Martinez, E. Lalinde, M. T. Moreno and A. J. Welch, New f . Chem., 1992,16,483.

7 I. Ara, J. Fornies, E. Lalinde, M. T. Moreno and M. Tomas, J. Chem. SOC., Dalton Trans., 1994,2735.

8 (a) R. Uson, J. Fornies, M. Tomas, 1. Ara, J. M. Casas and A. Martin,f. Chem. Soc., Dalton Trans., 1991,2253; (b) F. A. Cotton, L. R. Falvello, R. Uson, J. Fornies, M. Tomas, J. M. Casas and I . Ara, Znorg. Chem., 1987, 26, 1366; (c ) M. R . Churchill and B. G. DeBoer, Znorg. Chem., 1975, 14,2630.

9 R. Uson and J. Fornies, Znorg. Chim. Acta, 1992,165, 198. 10 A. J. Deeming, M. S. B. Felix and D. Nuel, Znorg. Chim. Acta, 1993,

213, 3; A. J. Deeming, M. S. B. Felix, P. A. Bates and M. B. Hursthouse, f . Chem. SOC., Chem. Commun., 1987, 461; P. Ewing and L. J. Farrugia, Organometallics, 1989,8, 1246 and refs. therein; D. Nucciarone, S. A. MacLaughlin, N. J. Taylor and A. J. Carty, Organometallics, 1988, 7, 106 and refs. therein; K. I. Hardcastle, A. J. Deeming, D. Nuel and N. I. Powell, J. Organomet. Chem., 1989, 375, 217; M. Catti, G. Gervasio and S. A. Mason, J. Chem. SOC., Dalton Trans., 1977,2260.

11 E. Maslowsky, jun., Vibrational Spectra of Organometallic Compounds, Wiley, New York, 1977, p. 437.

12 P. S. Pregosin and R. W. Kunz, 31P and 13C NMR of Transition MetalPhosphine Complexes, Springer, New York, 1979, pp. 107-109.

13 SHELXTL PLUS, Software Package for the Determination of Crystal Structures, Release 4.0, Siemens Analytical X-Ray Instruments, Madison, WI, 1990.

14 G. M. Sheldrick, SHELXL 93, FORTRAN 77 program for the refinement of crystal structures from diffraction data, University of Gottingen, 1993.

Received 23rd February 1995; Paper 5/0 1 1 OOK

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