2
Structure and Magnetism of Ternary Fluorides D. Babel, Tubingen (Germany) The magnetic behavior of transition-metal ions M2’ = Mn2;-, CO~’, Nil r, and Cu2 in ternary fluorides AMF3 and A2MF4 ( A : ~ = alkali-metal ion or TI'^) is related to the struc- ture of the compounds. Compounds AMF3 crystallize in rhombic, cubic, or hexagonal perovskite lattices depending on the Goldschmidt tolerance factors. Hexagonal lattices are present, above all, in the Cs compounds CsMnF3 (hexagonal BaTi03 type; also RbNiFx), CsCoF3 (BaRu03 type), and CsNiF3 (BaNi03 type). The number of MFb octahedra sharing faces increases in the order given. Except forNa2CuF4 (monoclinic, individual type), compounds A2M4 are formed only when A = K, Rb, TI, or Cs; they occur in the tetragonal K2MgF4 type, with the exception that cesium fluorides CS~MF~ crystallize in a hexagonal structure, details of which are not known. The magnetic properties range from antif’erromagnetism (KMF3) through normal paramagnetism (CsMF3, A ~ C U F ~ ) to strong ferrimagnetism (RbNiF3), and can be explained by considering the distances and coordination relations in the lattices. In particular, consideration of superexchange [*I and its dependence on the electron configuration of the cation and the arrangement of ions in the crystal permits qualitative interpretation of the magnetic properties. Thus, cases of 3-, 2-, 1-, and 0-dimensional superexchange can be differentiated which, in conjunction with the dependence on M-F dis- tances and M-F-M angles, account for the variations in magnetic behavior. [Lecture at Erlangen (Germany), on February loth, 19661 [VB 982.’289 IE] German version: Angew. Chem. 78, 451 (1966) [*I Superexchange is the magnetic interaction between para- magnetic cations by means of intermediary anions. Homopolar and Heteropolar Halogeno Esters of Phosphorus, Arsenic, and Antimony L. Kolditz, Berlin (Germany) Compounds of pentavalent phosphorus, arsenic, and anti- mony that carry both halogen and OR groups (R = alkyl or aryl) on the central atom, like the analogous simple pure and mixed halides, appear in homopolar and salt-like forms. In polar solvents equilibria are established between these two forms, the homopolar form undergoing association by means of halogen or OR bridges even in relatively dilute solution (e.g. 0.01 M in CH3CN). The behavior of chloro- (ethoxo)antimony compounds is typical, leading to equilibria according to (L = solvent) : 2 SbCln(OR)s-,.L =+ [SbCln+1(0R)~-nLz]+ + [SbC1n+l(OR)~-nl- (a) The situation is, however, complicated by exchange reac- tions between CI and OR. Alkoxofluorohydroxoarsenic compounds behave similarly; in the forms HO(RO)3AsF and HO(R0)2AsFz they show a strong tendency to condense, with elimination of OH groups and formation of oligomers containing As-0-As linkages. On reaction with KOCH3 in C2C13F3, arsenic pentafluoride gives the compound AsF40CH3 as well as K[AsF6]. The reaction mechanism is interpreted as : 2 AsFs i+ AsF++ AsF- AsF4’ + KOCH3 + AsF40CH3 + K+ (b) Equilibrium (c) was found when AsF3 was used as solvent: (AsF~OCH~)~ + [ASFZ(OCH~)~][A~F~~ [AsFz(OCH3)21+ + [Ash]- (c) Compounds P(OR)2F3 and [P(OR)J][PF~] are formed by exchange of Cl ligdnds in PC12F3 (homopolar) and [PCId][PF6] (salt-like) for OR groups. In polar solvents (ex. CH3CN) the homopolar substancc is transformed into the salt-like one in an equilibration of the above type. On de- composition of the salt-like compound the cation yields OP(OR)3. [Lecture at Mainz (Germany) on January 22nd, 19661 [VB 979,’286 IE] German version: Angew. Chem. 78, 451 (1966) Chemistry of Phosphorus, Arsenic, and Antimony Halides L. Kolditz, Berlin (Germany) We have studied the reactions of phosphorus, arsenic, and antimony halides with polar solvents. PFs, AsF5, and SbFS form adducts with CH3CN, and these dissociate in aceto. nitrile according to Eq. (a) (A = P, As, Sb): 2 AF5.CHKN + [AF4(CH3CN)2IA + [Ah- (a) An analogous formulation holds for S~CIS-CH~CN. The dis- sociation can be demonstrated by conductivity measurements and hydrolysis experiments. Hydrolysis occurs only at the cation for A := p, As, the anions remaining unchanged. This is true also for the compound PFs.N(CHd3, but AsFg,N(CH3)3 occurs only in the “homopolar” form and is unaffected by moisture; the arsenic compound is not even wetted by water. A solution of chlorine in AsC13, which contains the solvate AsCI3-Cl2 but no ASCIS,is a very strong chlorinating agent. Arsenic and antimony compounds that contain a CF3 group as well as halogen (general formula AXz(CF3)3) are more stable than the corresponding simple halides. [SbBrsl- ions decompose in CH3CN according to Eq. (b). The structure of [SbBr& may thus be represented by the (b) formula [SbBrd.Br$. Easy loss of bromine occurs also with ShBr5,O(C2H5)2, which can be prepared only with an excess of antimony (e.g. Br:Sb = 4.7: 1). SbBrS, like ASCIS, is not known in the pure form. The system SbC15, SbFS contains associated apolar and also polar forms. The most stable compound is SbCbF, which is tetrameric in the solid state: distorted SbC14 tetrahedra are linked by asymmetrical fluorine bridges (varying Sb-F distances). All the compounds mentioned tend to exchange halogen. The equilibria occurring in solution are dependent on solvent, concentration, and temperature, and the halogen-transferring action of the apolar substances differs from that of the salt- like forms, so that halogenation can be readily controlled. [Lecture at Aachen and Frankfurt/Main (Germany), on January 21st and 27th, 19661 [SbBr,j- --f SbBr3 + Br-Brz- PB 980/287 I€] German version: Angew. Chem. 78, 452 (1966) Structures and Reactions of the Products of Reaction of Hydrogen Cyanide with Hydrogen Halides E. Allensfeiri, A. Schmidt, and V. Beyl, Stuttgart (Germany) Structural investigation of the “sesquihdiides of hydrocyanic acid,” 2 HCN.3 HX (X = CI or Br), mostly by infrared spectroscopy but also by chemical methods, has shown that they are N-(diha1ogenomethyl)formamidinium halidesC21, [HXZC-NH-CH-NH~]+X-, in accordance with the view of Gattermann and Schnitzspahn (11. Angew. Chem. internat. Edit. J Vol. 5 (1966) 1 No. 4 425

Structures and Reactions of the Products of Reaction of Hydrogen Cyanide with Hydrogen Halides

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Structure and Magnetism of Ternary Fluorides

D. Babel, Tubingen (Germany)

The magnetic behavior of transition-metal ions M2’ = Mn2;-, C O ~ ’ , Nil r, and Cu2 in ternary fluorides AMF3 and A2MF4 ( A : ~ = alkali-metal ion or TI'^) is related to the struc- ture of the compounds. Compounds AMF3 crystallize in rhombic, cubic, or hexagonal perovskite lattices depending on the Goldschmidt tolerance factors. Hexagonal lattices are present, above all, in the Cs compounds CsMnF3 (hexagonal BaTi03 type; also RbNiFx), CsCoF3 (BaRu03 type), and CsNiF3 (BaNi03 type). The number of MFb octahedra sharing faces increases in the order given. Except forNa2CuF4 (monoclinic, individual type), compounds A2M4 are formed only when A = K, Rb, TI, or Cs; they occur in the tetragonal K2MgF4 type, with the exception that cesium fluorides C S ~ M F ~ crystallize in a hexagonal structure, details of which are not known. The magnetic properties range from antif’erromagnetism (KMF3) through normal paramagnetism (CsMF3, A ~ C U F ~ ) to strong ferrimagnetism (RbNiF3), and can be explained by considering the distances and coordination relations in the lattices. In particular, consideration of superexchange [ * I and its dependence on the electron configuration of the cation and the arrangement of ions in the crystal permits qualitative interpretation of the magnetic properties. Thus, cases of 3 - , 2-, 1-, and 0-dimensional superexchange can be differentiated which, in conjunction with the dependence on M-F dis- tances and M-F-M angles, account for the variations in magnetic behavior. [Lecture at Erlangen (Germany), on February loth, 19661

[VB 982.’289 IE] German version: Angew. Chem. 78, 451 (1966)

[*I Superexchange is the magnetic interaction between para- magnetic cations by means of intermediary anions.

Homopolar and Heteropolar Halogeno Esters of Phosphorus, Arsenic, and Antimony

L. Kolditz, Berlin (Germany)

Compounds of pentavalent phosphorus, arsenic, and anti- mony that carry both halogen and OR groups (R = alkyl or aryl) on the central atom, like the analogous simple pure and mixed halides, appear in homopolar and salt-like forms. In polar solvents equilibria are established between these two forms, the homopolar form undergoing association by means of halogen or OR bridges even in relatively dilute solution (e.g. 0.01 M in CH3CN). The behavior of chloro- (ethoxo)antimony compounds is typical, leading to equilibria according to (L = solvent) :

2 SbCln(OR)s-,.L =+ [SbCln+1(0R)~-nLz]+ + [SbC1n+l(OR)~-nl- (a)

The situation is, however, complicated by exchange reac- tions between CI and OR. Alkoxofluorohydroxoarsenic compounds behave similarly; in the forms HO(RO)3AsF and HO(R0)2AsFz they show a strong tendency to condense, with elimination of OH groups and formation of oligomers containing As-0-As linkages.

On reaction with KOCH3 in C2C13F3, arsenic pentafluoride gives the compound AsF40CH3 as well as K[AsF6]. The reaction mechanism is interpreted as :

2 AsFs i+ AsF++ AsF- AsF4’ + KOCH3 + AsF40CH3 + K + (b)

Equilibrium (c) was found when AsF3 was used as solvent:

( A s F ~ O C H ~ ) ~ + [ A S F Z ( O C H ~ ) ~ ] [ A ~ F ~ ~ [AsFz(OCH3)21+ + [Ash]- (c)

Compounds P(OR)2F3 and [P(OR)J][PF~] are formed by exchange of Cl ligdnds in PC12F3 (homopolar) and [PCId][PF6] (salt-like) for OR groups. I n polar solvents ( e x . CH3CN) the homopolar substancc is transformed into the salt-like one in an equilibration of the above type. On de- composition of the salt-like compound the cation yields OP(OR)3. [Lecture at Mainz (Germany) on January 22nd, 19661

[VB 979,’286 IE] German version: Angew. Chem. 78, 451 (1966)

Chemistry of Phosphorus, Arsenic, and Antimony Halides

L. Kolditz, Berlin (Germany)

We have studied the reactions of phosphorus, arsenic, and antimony halides with polar solvents. PFs, AsF5, and SbFS form adducts with CH3CN, and these dissociate in aceto. nitrile according to Eq. (a) (A = P, As, Sb):

2 AF5.CHKN + [AF4(CH3CN)2IA + [ A h - (a)

An analogous formulation holds for S ~ C I S - C H ~ C N . The dis- sociation can be demonstrated by conductivity measurements and hydrolysis experiments. Hydrolysis occurs only at the cation for A := p, As, the anions remaining unchanged. This is true also for the compound PFs.N(CHd3, but AsFg,N(CH3)3 occurs only in the “homopolar” form and is unaffected by moisture; the arsenic compound is not even wetted by water. A solution of chlorine in AsC13, which contains the solvate AsCI3-Cl2 but no ASCIS, is a very strong chlorinating agent. Arsenic and antimony compounds that contain a CF3 group as well as halogen (general formula AXz(CF3)3) are more stable than the corresponding simple halides. [SbBrsl- ions decompose in CH3CN according to Eq. (b). The structure of [SbBr& may thus be represented by the

(b)

formula [SbBrd.Br$. Easy loss of bromine occurs also with ShBr5,O(C2H5)2, which can be prepared only with an excess of antimony (e.g. Br:Sb = 4.7: 1). SbBrS, like ASCIS, is not known in the pure form. The system SbC15, SbFS contains associated apolar and also polar forms. The most stable compound is SbCbF, which is tetrameric in the solid state: distorted SbC14 tetrahedra are linked by asymmetrical fluorine bridges (varying Sb-F distances). All the compounds mentioned tend to exchange halogen. The equilibria occurring in solution are dependent on solvent, concentration, and temperature, and the halogen-transferring action of the apolar substances differs from that of the salt- like forms, so that halogenation can be readily controlled. [Lecture at Aachen and Frankfurt/Main (Germany), on January 21st and 27th, 19661

[SbBr,j- --f SbBr3 + Br-Brz-

P B 980/287 I € ] German version: Angew. Chem. 78, 452 (1966)

Structures and Reactions of the Products of Reaction of Hydrogen Cyanide with

Hydrogen Halides

E. Allensfeiri, A. Schmidt, and V. Beyl, Stuttgart (Germany)

Structural investigation of the “sesquihdiides of hydrocyanic acid,” 2 HCN.3 HX (X = CI or Br), mostly by infrared spectroscopy but also by chemical methods, has shown that they are N-(diha1ogenomethyl)formamidinium halidesC21, [HXZC-NH-CH-NH~]+X-, in accordance with the view of Gattermann and Schnitzspahn (11.

Angew. Chem. internat. Edit. J Vol. 5 (1966) 1 No. 4 425

On hydrolysis with an equivalent amount of water in ether, N-formylformamidinium bromide ( I ) [21 [obtainable by reaction of N-(dibromomethy1)formamidinium bromide with dimethyl sulfoxide] yields N-formylformamide (2) (m.p. 42 O C ; b.p. 119 OC/I2 mm Hg) in accord with Eq. (a).

[O=CH-NH-CH=NH21+Br- + H20 +

(1) O=CH-NH-CH=O + NH4Br (a)

(2)

N-Formylformamide (2) can also be prepared by hydrolysis of N-(dichloromethyl)formamidinium chloride with traces of water in the presence of an excess of sodium hydrogen car- bonate:

[CIZCH-NH-CH=NH~]+CI-+ 2 H20 -+

O=CH-NH-CH=O + NH4CI + 2 HCI (b)

2 HCI + 2 NaHCO3 --f 2 NaCl + 2 COz + 2 H20

The latter process is suitable also for the preparation of N-alkyl-N-formylformamides, starting with the N,N'-dialkyl-N-(dich1oromethyl)formamidinium chlorides [HClzC-NR-CH=NHR]+Cl- obtained by Jentzsch [31. Hydrogen cyanide, chlorocyanogen, and trichloroaceto- nitrile, without or in the presence of hydrogen chloride, afford N-(dich1oromethyl)formamidinium chloride [21, cyan- uric chloride [41, and 2,4,6-tris(trichloromethyl)-s-triazine W, respectively, by di- or trimerisation of the cyano compounds or of the hydrogen chloride adducts that are the primary products. However, we have shown that in the presence of

antimony(V) chloride and hydrogen chloride, hexachloro- antimonates (3) are produced. The antimony(V) chloride takes part in the reaction of the cyano compounds with hydrogen chloride according to Eq. (c) :

The unstable imidium chlorides (4), which are in equilibrium with the starting materials, are rapidly trapped as the stable hexachloroantimonates (3) ; the slow dimerization or trimerization is thus prevented. [Lecture at Clausthal-Zellerfeld (Germany), on January 21st, 19661 [VB 981/288 IE]

German version: Angew. Chem. 78, 452 (1966)

[ I ] L. Gattermann and K . Schnitzspahn, Ber. dtsch. chern. Ges. 31, 1770 (1898). [ 2 ] E. Allenstein, A. Schmidt and Y. Beyl, Chem. Ber. 99, 431 (1966). [3] W. Jentzsch, Chern. Ber. 97, 1361, 2755 (1964). [4] A. Hantzsch and L. Mat, Ber. dtsch. chern. Ges. 28, 2466 ( 1 895). [ 5 ] H. Herlinger, Angew. Chem. 76, 437 (1964); Angew. Chem. internat. Edit. 3, 378 (1964). [6] E. Allensrein and A. Schmidt, Chem. Ber. 97, 1863 (1964). [7] E. Allenstein and A . Schmidt, Chem. Ber. 97, 1286 (1964). [8] E. Allenstein and A. Schmidt, unpublished work.

SELECTED ABSTRACTS

The synthesis of 2-aminoethylphosphines (C2H&N-(CHz)z-PRz by reactions (a) to (d) has been reported by K. Issleib and R. Rieschel.

Reaction (c) is carried out in chlorobenzene, so that the phosphonium salt (3a) precipitates; after separation, (3u) is decomposed in ether in accordance with Equation (d). The products ( I ) to (3) can be isolated as colorless oils by vacuum distillation. They are soluble in ether, tetrahydrofuran, di- oxane, benzene, and acetone, but not in water. The infrared spectra of ( I ) to (3) contain the triethylamine stretching bands, which are still present after the reaction with excess ethyl iodide. Thus only the phosphorus is quaternized. Oxidation of ( I ) to (3) with H202 in ether leads to the formation of the phosphine oxides. / Chem. Ber. 98, 2086 (1965) / -Gn. [Rd 426/635 IE]

The sodium-catalysed alkylation of 3-picolhe with styrene and butadiene has been achieved by Y. I. Chumakov and V. M. Ledovskikh. 3-Picoline ( I ) was boiled (145 "C) under N2 with sodium [O. 1 g-atom per mole of (I)]. An equimolar quantity of styrene was added dropwise over half an hour, and the mixture was refluxed for a further two hours. The products obtained included those resulting from mono- alkylation [(2), 23.2 % yield] and from dialkylation [(3), 17.4 %I.

V H 3 CHpCHPh* ~ H 3 - n ( C H 2 c H 2 P h ) ~ (2), n = 1 (3), n = 2

{ I )

When butadiene was used instead of styrene, 2.4 % of the triply-substituted product was obtained, as well as 35.4 % of the mono-adduct and 16.4 % of the di-adduct. It was assumed that these adducts have the structure (4). (4), n = 1 could

be reduced to n-amylpyridine, and yielded acetaldehyde on ozonolysis, indicating a 1 ,Caddition. A small quantity of the 1,2-addition product was also detected by infrared spectroscopy. The additions must take place on a derivative of ( I ) that has been metalated a t the methyl group. The proton mobility was comparable to that of the 2- and 4- isomers. / Tetrahedron 21,937 (1965) / -Eb. [Rd 423/632 IE]

426 Angew. Chem. internat. Edit. 1 Vol. 5 (1966) 1 No. 4