Sinthesis and Molecular Structure of Novel Dihalogeno-dicyanoaurate Complexes

Abstract

Interaction of tetraorganylphosphonium halides with potassium dichloro-, dibromo- and diiododicyanoaurate in water followed by recrystallization from acetonitrile has been used to synthesize gold(III) ionic complexes [Me₄P][Au(CN)₂Cl₂] (1), [Ph₃PR][Au(CN)₂Hal₂] (Hal = Cl,
R = (CH₂)₆Me (2), (CH₂)₂C(O)OH (3); Hal = Br, R = CH₂CN (4); Hal = I, R = CH₂CN (5)) and [Ph₃PCH=CHPPh₃][Au(CN)₂Cl₂]₂ (6). In a similar way complex [Ph₄Sb][Au(CN)₂Cl₂] (7) has been obtained by the interaction of tetraphenylantimony chloride with potassium dichlorodicyanoaurate. Complexes 3, 5–7 have been structurally characterized by the X-ray analysis method. According to the X-ray data phosphorus and antimony atoms in crystals 3, 5–7 have a slightly distorted tetrahedral coordination (the CPC bond angles are 107.5(2)-111.8(3)° (3), 106.0(3)-111.5(3)° (5), 106.7(4)-111.8(4)° (6), the CSbC bond angles are 100.5(7)-114.6(5)° (7); the P–C bond lengths are 1.788(5)-1.807(5) Å (3), 1.765(6)-1.821(6) Å (5), 1.781(8)-1.810(8) Å (6); the Sb–C bond lengths are 2.070(11)-2.121(12) Å (7)). Gold atoms in [Au(CN)₂Hal₂]^- anions have a slightly distorted square planar coordination (the HalAuHal and CAuC trans-angles are quite close to 180°; the CAuHal cis-angles vary from 88.05° to 92.48°), the Au–Hal bond lengths are 2.328(3) Å (3), 2.393(2), 2.411(2) Å (6), 2.4223(12) Å (7) for Au–Cl and 2.609(3), 2.598(3) Å (5) for Au–I; the Au–C bond lengths are 1.981(7) Å (3), 1.996(7), 2.006(8) Å (5), 1.978(12), 2.001(13) Å (6), 2.040(15) (7). In crystal 5 two types of crystallographically independent centrosymmetric [Au(CN)₂I₂]^- anions are observed. The structural organization of complexes 3, 5–7 is caused by the different noncovalent interactions: С–H∙∙∙N≡C 2.55–2.74 Å (3, 5–7), O–H∙∙∙N≡C 2.03 Å, С–H∙∙∙O=C 2.52 Å, C–H∙∙∙Cl–Au 2.88–2.93 Å (3), Au–I∙∙∙I–Au 3.925(4)  Å (5), C–H∙∙∙Cl–Au 2.91 Å (6).