Gold(I) and Silver(I) complexes of diphosphacyclobutadiene cobaltate sandwich anions

Abstract

The synthesis and structural characterization of the first coordination compounds of bis(diphosphacyclobutadiene) cobaltate anions [M(P2 C2 R2)2]- is described. Reactions of the new potassium salts [K(thf)3{CO(n4-P2C2tPent2)2}] (1) and [K(thf)4{Co(n4-P2C2AD2)2}] (2) with [AuCl(tht)] (tht=tetrahydrothiophene), [AuCl(PPh3)] and Ag[SbF6] afforded the complexes [Au{Co(P2C2tPent2)2}(PME3)2] (3), [Au{CO(P2C2Ad2)2}]x (4), [Ag{Co(P2C2Ad2)2}]x (5), [Au(PME3)4][Au{Co(P2C2Ad2)2}2] (6), [K([18]crown-6)(thf) IND. 2][Au{Co(P2C2Ad2)2}2] (7), and [K([18]crown-6)(thf)2][M{Co(P2C2Ad2)2}2] (8: M=Au 9: M=Ag) in moderate yields. The molecular structures of 2 and 3, and 6–9 were elucidated by X-ray crystallography. Complexes 4–9 were thoroughly characterized by 31 P and 13 C solid state NMR spectroscopy. The complexes [Au{Co(P2C 2Ad2)2}]x (4) and [Ag{Co(P2C2Ad2)2}] x (5) exist as coordination polymers in the solid state. The linking mode between the monomeric units in the polymers is deduced. The soluble complexes 1-3, 6, and 7 were studied by multinuclear 1 H-, 31 P{1 H}-, and 13 C{1 H} NMR spectroscopy in solution. Variable temperature NMR measurements of 3 and 6 in deuterated THF reveal the formation of equilibria between the ionic species [Au(PME3)4] +, [Au(PME3)2] +, [Co(P2C2R2)2] -, and [Au{Co(P2C2R2)2}2]- (R=tPent and Ad).