Cationic diamine complexes of...

Indian Journal of ChemistryVol. 30A. February 1

,.PRASAD et al.: DI/\MINE COMPLEXES OF CYCLOPF1\T,\DIE1\YL.Rl:nlENIUM\lI:

(C) Preparation oj[RuCp(EPh;)(dmgH) complexes[RuCp(Eph,hCI) (0.1 mmolc) and dirnethylglyox-

ime (0.02 g; 0.2 mmole) in methanol (25 rnl) was ref-luxed in the presence of sodium acetate (0.2 g). Thereaction mixture was concentrated, cooled. the yel-low solid filtered off, washed with methanol. fol-lowed by ether and dried in vacuo over CaCic'

Results and DiscussionTreatment of chlorocornplcxes [RuCp(EPh1)cCI]

with a very large excess of diamincs in methanol,both at room temperature and under refluxing con-ditions resulted in the formation of yellow diarninccationic complexes by rapid displacement of one ofthe bulky EPh, groups and the chloride ion in morethan 50% yield. Their microanalytical data, meltingpoints and the empirical formulae arc listed in Table1. All the complexes are stable in air at room tem-perature in solid state and arc highly soluble in or-ganic polar solvents like, CHcCI2• CHCI,. acetone.DMF, etc. However, the tetra phenyl borate salts arconly sparingly soluble in methanol and ethanol.The molar conductivities (t.M) of their hexafluor-

ophosphate salts (1 x 10 -..l molar solutions) werefound to be in the range of 145 ± 5 Q - Ierne mol . I.This is well within the range for I: I electrolytes 1-1.The complexes 55-57 shown in Table I have molarconductances of around 6 Q - I ern-mol I underidentical conditions, indicating their nonelectrolyticnature.The reaction of ethylenediamine. l,2-diamino-

propane and 1.2-phenylenediamine were smooth.These behaved as bidcntatc ehelating Iigands re-placing CI and one EPh, from [RuCp(EPh,)2Ci] inmethanol by both the methods (A) and (B). 1,3-Di-aminopropane behaved as a bidentate ligand undermethod (A) but under method (B) it gave a mixtureof mono- and bidentate products. With the increasein stirring period, the monodentate products gotgradually converted into bidentate ones. Thus theirmonodentate cations have not been isolated.The products of the reactions of 1,6-diaminohex-

ane under refluxing condition (method A) yielded amixture of monodentate and bidentate diaminecomplexes. But seemingly the amino groups and thesix-carbon alkyl chain underwent some sort of rear-rangement under the reaction conditions (methodA), because no proper PMR signals for - NH2 and- CH2 - protons were observed in the PMR spect-ra of the products (vide supra). Variation in the reac-tion period has no effect on the nature of the mix-ture-product. In case only one molar excess of 1.6-diaminohexane was stirred with [RuCp(EPh')2Clj inmethanol, the cation complex [RuCp(EPh1)2( I .6-dahl]" was formed as a result of the facile ionization

/

of chloride ion with subsequent attachment of dia-mine molecule. l.o-Diaminohexanc did not serve asa bideruatc ligand in its reactions withrRuCpiEPh,),CI! even after stirring upto 16 hri method B).

Formation of hydride derivative.[RuCp(EPhJcHJ* has been frequently encounteredas a parallel side reaction when the diarnincs andprecursor complex arc taken in I: I molar ratio. It iswell documented I' that when alcohols which con-tain a-hydrogen arc used as reaction medium for(RuCp(EPh,lcCI). bases catalyse formation of hy-dride complexes. However, this side reaction iscompletely suppressed when the diamine is taken inexcess amount. yielding exclusively diamine substi-tution products. Under these conditions amines di-rectly displaces solvent (alcohol) molecule from thesolvated cation of the precursor complex ratherthan abstracting proton and facilitating-hydrogenmigration to give hydrides. Since the correspondinghydride complexes do not undergo substitutionreaction by diarninc. under similar conditions thepossibility of the derivative as the intermediate isruled out.

II< spectraThe IR and the PMR spectral data of the repre-

sentative complexes arc listed in Table 2. In their IRspectra all the complexes exhibited two absorptionbands in the vN - H. viz vjNH) and v,jNH) in theregion of :;250-:;:;50 crn " I. The absorption handscharacteristic of cyclopcntadienyl, EPh1 and coun-ter anions dominate the rest of the IR spectrum.

Iff N/'vll< spectraAs expected. all complexes contained only one

signal corresponding to cyclopentadicnyl protons.Coordinated NH: protons appeared dcshicldcd II,by nearly I ppm. The cyclopcntadicnyl proton sig-nals in bidcntatc chelate complexes is invariablyshifted low field than that in the correspondingmonodcntatc cations (complexes 2~- 36 j. Thisdownficld shift could tentatively be assigned to in-creased electron density on Ru atom!".

Visible spectraThe lowest energy band in the diamine complexes

assigned to Ru ~ Cp charge transfer (MLCT) ap-pcarcd at :;55-360 nm which is only little blue shift-ed compared to that in [RuCp(PPhJ~CIj (365 nm).Complexes iRuCp(EPhJcL]' where L is a non

zr-bonding ligand arc well known to undergo solvo-

'The hydridc-, thus obtained have been ch.uactcriscd bv COJll-paring thL· reaction products with the authentic samples!" II.

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INDIAN J CHEM, SEe. A, FEBRUARY 1991

Table I-Microanalytical data

Complex m.p. . Found (calc). %°C C H N

I. [RuCp(PPh,)(en)] (PF6) 160 52.41 (52.17) 5.01(4.87) 5.10(4.87)2. [RuCp(PPh,)(en)] (PF6) 165 47.70(47.39) 4.66(4.42) 4.72(4.42)3. [RuCp(PPh,)(en)] (BPh.) 188 72.69(72.86) 5.87(5.95) 3.59(3.4 7)4. [RuCp(AsPh,)(en)] (BF.) 160 48.73(48.47) 4.71(4.52) 4.43(4.52)5. [RuCp(AsPh,)(en)](PF6) 165 46.60( 46.31 ) 4.08(4.14) 4.08(4.14)6. [RuCp(AsPh,)(en)] (BPh.) 187 69.31(69.10) 5.69(5.64) 3.22(3.29)7. [RuCp(SbPh,)(en)] (BF.) 162 44.87(45.05) 4.41(4.20) 4.32(4.20)8. [RuCp(SbPh,)(en)] (PF6) 166 4 J.7 I (41 .44 ) 3.67(3.87) 3.84(3.87)9. [RuCp(SbPh,)(en)] (BPh.) 188 65.65(65.48) 5.44(5.35) 3.23(3.12)

10. [RuCp(PPh.)( 1,2-dap)] (BF.) 161 53.23(52.97) 5.20(5.09) 4.64(4.75)·11. [RuCp(PPh,)( 1,2-dap)] (PF6) 169 48.50( 48.22) 4.47(4.64) 4.42(4.33)12. [Ru Cp(PPh,)( 1,2-dap)] (BPh.) 187 73.33(73.08) 6.23(6.09) 3.50(3.41 )13. [RuCp(AsPh,)( 1,2-dap)] (BF.) 161 49.11(49.29) 4.87(4.74) 4.56(4.42)14. [Ru Cp(AsPh,)( 1,2-dap)] (PF6) 167 45.33(45.15) 4.47(4.34) 4.20(4.05)15. [RuCp(AsPhJ)(l,2-dap)] (BPh.) 181 69.21(69.36) 5.83(5.78) 3.29(3.24)16. [RuCp(SbPhJ)( 1,2-dap)] (BF.) 160 45.97(45.88) 4.55(4.41 ) 4.19(4.12)17. [Ru Cp(SbPh,)( 1,2-dap)] (PF6) 168 42.43( 42.28) 3.98(4.07) 3.82(3.79)18. [Ru Cp(SbPh,)( 1,2-dap)] (BPh.) 190 65.62(65.79) 5.62(5.48) 3.18(3.07)19. [RuCp(PPh,)( 1,3-dap)] (BF.) 162 53.16(52.97) 5.21(5.09) 4.61(4.75)20. [RuCp(PPh,)( 1,3-dap)] (PF6) 165 48.37( 48.22) 4.54(4.64) 4.52(4.33)21. [RuCp(PPh,)( 1,3-dap)] (BPh.) 175 73.22(73.08) 6.00(6.09) 3.39(3.41 )22 .. [RuCp(AsPh,)( 1,3-dap)] (BF.) 160 49.15( 49.29) 4.89(4.74) 4.53(4.42)23. [RuCp(AsPhJ)( 1,3-dap)] (PF6) 166 45.02(45.15) 4.21(4.34) 4.16(4.05)24. [RuCp(AsPh,)(l,3-dap)](BPh.) 186 69.48(69.36) 5.83(578) 320(3.24 )25. [RuCp(SbPhJ)( 1,3-dap)] (BF.) 162 45.97(45.88) 4.26(4.41 ) 4.02(4.12)26. [RuCp(SbPh,)( 1,3-dap)] (PF6) 168 42.41 (42.28) 4.25(4.07) 3.92(3.79)27. [RuCp(SbPh,)( 1,3-dap)] (BPh.) 188 65.87(65.79) 5.59(5.48) 3.17(3.07)28. [RuCp(PPh,h( 1,6-dah)] (BF.) 120 63.29(63.16) 5.64(5.71) 3.09(3.14)29. [RuCp(PPh,h( 1,6-dah)] (PF6) 110 59.52(59.31) 5.42(5.36) 2.87(2.94)30. [Ru Cp(PPh,h( 1,6-dah)] (BPh.) 115 75.81(75.73) 6.41 (6.31) 2.43(2.49)31. [RuCp(AsPh,h( 1,6-dah)] (BF.) 121 57.64(57.49) 5.33(5.20) 2.96(2.85)32. [RuCp(AsPh,),( 1,6-dah)] (PF6) llt 54.13(54.28) 4.87(4.91 ) 2.76(2.69)33. [RuCp(AsPh,),( 1,6-dah)] (BPh.) 117 70.30( 70.24) 5.69(5.85) 2.25(2.31 )34. [Ru Cp(SbPh,),( 1,6-dah)] (BF.) 122 52.37(52.49) 6.77(6.61) 2.69(2.61 )35. [Ru Cp(SbPh,),( 1,6-dah)] (PF6) III 49.89(49.80) 4.43( 4.50) 2.43(2.4 7)36. [Ru Cp(SbPh,W ,6-dah)](BPh.) 117' 65.16(65.21) 5.64(5.43) 2.10(2.14)37. [RuCp(PPh,)(I,2-dab)] (BF.) 125 55.80(55.86) 4.59(4.49) 4.37(4.49)38. [RuCp(PPh,)( 1,2-dab)] (PF,,) 118 51.24(51.10) 4.04(4.11) 4.23(4.11)39. [RuCp(PPh,)( I ,2-dab)] (BPh.) 110 74.45(74.39) 5.56(5.61 ) 3.23(3.27)40. [RuCp(AsPh,)( 1.2-dab)] (BF.) 128 52.37(52.17) 4.14(4.20) 4.29(4.20)41. [RuCp(AsPh,)( 1,2-dab)] (PF,,) 118 48.11(48.00) 3.77(3.86) 3.81(386)42. [RuCp(AsPh,)( I ,2-dab)] (BPh.) 112 70.83(70.75) 5.42(5.34) 3.10(3.11 )43. [RuCp(SbPh,)( 1,2-dab)] (BF.) 128 48.59(48.76) 3.85(3.92) 3.97(3.92)44. [RuCp(SbPh,)( I ,2-dab)] (PF6) 118 45.26( 45.(9) 3.52(3.63) 3.68(3.63)45. [Ru Cp(SbPh,)( 1,2-dab)] (BPh.) 112 6730(6725) 5.15(5.08) 2.92(2.96)46. [RuCp(PPh,)(dmgH,)] (BF.) 142 51.44(5135) 4.60(4.44) 4.37(4.-+4)47. [RuCp(PPh,)(dmgH,)] (PF,,) 186 47.19(47.02) 4.01(4.06) 4.15(4.06)48. [RuCp(PPh,)(dmgH,)] (BPh4) 180 70.83(7().92) 5.67(5.56 ) 3.20(3.24)49. [RuCp(AsPh,)(dmgH,)] (BF.) 140 48.09( 48.(0) 4.26(415) 408(4.15)50. [RuCp(AsPh,)(dmgH,)] (PF,,) 185 44.33(44.20) 374(3.82) 3.90(3.82)

Contd

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PRASAD et al.: DIAMINE COMPLEXES OF CYCLOPENTADIENYLRUTHENIUM(II)

Complex

Table I-Microanalytical data- Contd.

51. [RuCp(AsPh3)(dmgHJ] (BPh4)52. [RuCp(SbPh))(dmgH1)] (BF4)53. [RuCp(SbPh1)(dmgH2)] (PFo)54. [Ru Cp(SbPh»)(dmgH2)] (BPh,l55. [RuCp(PPh3)(dmgH)]56. [RuCp(AsPh))(dmgH)]57. [RbCp(SbPh1)(dmgH)]

m.p.°C

180143185178210211213

Found (calc), %H

5.23(5.29)3.79(3.88)3.63(3.59)5.11(5.03)4.92(4.97)4.55(4.60)4.34(4.26)

N3.05(3.09)3.81(3.88)3.63(3.59)2.87(2.94)5.20(5.16)4.76(4.77)4.57(4.42)

C67.41(67.~~)44.75(44.89)41.67(41.55)

64.03( 64.17)59.83(59.67)55.12(55.20)51.08(51.12)

Colour of the compound No., 37-45 yellowish green, the rest, bright yellow

Complex

Table 2- IR and IH NMR spectral assignments of some selected complexes

IR 'H NMR(MPPM)V"_H cm-I

Va~ Vs .Hcp H( -NH2) H(diamine skelton)

3330 3280 4.35 2.1 2.83340 3285 4.35 2.1 1.1(CH;) 2.4-2.83340 3290 4.4 2.1(8H, NH2 and 2.8(2H, Middle-Cl-I, - )

terminal CH2)3380, 3320,3340, 4.2 1'.9(2H) 1.4,1.55(8H)3395 2.5(4H-terminal CH1)3340 3280 4.4 3.9OH 3450 5.0 2.1(CH))OH 3400(broad) 4.70 2.1(CH1)

[RuCp(PPh))(en)](PFo)[RuCp(PPh»)( 1.2 dap)](PFo)[RuCp(PPh))( 1.3 dap)](PFo)

[RuCp(PPh»)( 1.6 dah)](PFo)

[RuCp(PPh1)(0-Phda)](PFo)iRuCp(PPh»)(dmgHJ](PF.)[RuCp{PPhJ{dmgH)]

lysis IH, hence the corresponding aliphatic diaminecomplexes especially bidentate chelate ones are ex-pected to give solvated cations of the type

[Cp(EPh,)Ru(N - N)j+Solvent--~.' [Cp(EPh,)(Sol)Ru+ -N-N]

These cations could lead to many interesting reac-tions which is our current interest of investigation.Acknowledgement

We thank RSIC(CDRl), Lucknow for providingcertain microanalytical data. One of the authors(RP) also thanks CSIR, New Delhi, for providing fi-nancial assistance during the period of this work.References

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