Reactivity of bis(diphenylphosphino)methane in cationic octahedral iron(II) derivatives. X-Ray structure of mer-[FeCl{(Ph2P)2 C(AuPPh3)2}(CNPh)3]PF6

Abstract

Treatment of the cationic complexes [FeL(dppm)(CNPh)₃]ⁿ⁺[L = CNPh, n= 2, (1a); L = PPh₃, n= 2, (1b); L = I^–, n= 1, (1c); L = Cl^–, n= 1, (1d)](dppm = Ph₂PCH₂PPh₂) with KOH gives the corresponding deprotonated species [FeL{(Ph₂P)₂CH}(CNPh)₃]^[n–1)+(2a)–(2d). Complexes (2a) and (2d) react with [AuCl(tht)](tht = tetrahydrothiophene) affording the bimetallic complexes [FeL{(Ph₂P)₂CH(AuCl)}(CNPh)₃]^(n–1)+(3a) and (3d). Reaction of (2c) with 0.5 equivalent of [Au(tht)₂]PF₆ gives the trimetallic compound [{Fel[(Ph₂P)₂CH](CNPh)₃}₂Au]PF₆(4), and with [Au(PPh₃)(tht)]PF₆ gives mer-[Fel{(Ph₂P)₂CH(AuPPh₃)}(CNPh)₃]PF₆(5c). The analogous mer-[FeCl{(Ph₂P)₂CH(AuPPh₃)}(CNPh)₃]PF₆(5d) is obtained by reaction of (1d) with 1 equivalent of [AuCl(PPh₃)] in the presence of KOH. Addition of 2 equivalents of [AuCl(PPh₃)] to a dichloromethane solution of (1a), (1c), (1d), or [Fe(dppm)(CNC₆H₄Me-4)₄][PF₆]₂(1e) in the presence of an excess of KOH affords [FeL{(Ph₂P)₂C(AuPPh₃)₂}(CNR)₃]ⁿ⁺(6a) and (6c)–(6e). The structure of complex (6d) has been determined by X-ray analyses, showing a short Au–Au contact.