Metallophilicity in annular Ru2M2 derivatives of (HMB)RuII(tpdt) versus (Bis)-η2-dithiolate bonding in Ru2M derivatives of Cp*RuIII(tpdt) (HMB = η6-C6Me6; Cp* = η5- C5Me5; M = CuI, Ag(I,II), Au (I,)

Abstract

The reaction of [(HMB)RuII(η3-tpdt)] (1: HMB = η6-C6Me6; tpdt = S(CH2CH 2S-)2) with [Cu(MeCN)4]PF 6, AgPF6, and (PPh3)AuCl gave the annular species [{(HMB)RuII(μ3-η1: η1:η3-tpdt)}2(M)2] 2+ [3: M = CuI; 3A: (M)2 = CuI, CuI(MeCN); 4: M = AgI ; 6: M = AuI], isolated as PF6 salts in high yields. Complex 6 was formed in a reversible process with [{(HMB)-RuII(μ-η1:η3- tpdt)}(AuPPh3)]+ (5) involving dissociation/association of PPh3. Similar reactions of [Cp*RuIII(η3-tpdt)] (2: Cp* = η5-C5Me5) gave, respectively, the cationic metal-metal bonded Ru2M complexes [{Cp*Ru(μ- η2:η3-tpdt)}2M]n+ (7: M = CuI, n = 1; 8: M = AgII, n = 2) and [{Cp*Ru(μ- η1:η3-tpdt)}(AuPPh3)]+ (9), isolated as PF6 salts in 71, 73, and 72% yields, respectively. In MeCN or THF for an extended period, 9 underwent transformation to a mixture of complexes, from which [{Cp*Ru}2{μ-η6- (S(CH2)2S(CH2)2SAuPPh 3)2}]2+ (10), containing a μ-S2 bridge, and [{Cp*Ru(μ-η1:η1: η3-tpdt)}(AuPPh3)2]+ (11) could be identified. The new complexes, 3-9 and 11, were all spectroscopically characterized, and the X-ray crystal structures of 3-10 have been determined. Cyclic voltammetry experiments were performed on compounds 3A, 4, and 6-8 at 233 K in CH2Cl2. 7 and 8 could be oxidized and reduced in several one-electron steps to form moderately stable species with extensive electron delocalization between the Ru2M atoms. An EPR spectrum of 8, a Ag(II) (d9) species, was obtained at liquid He temperatures.