Metallophilicity in Annular Ru 2 M 2 Derivatives of (HMB)Ru II (tpdt) versus (Bis)-η 2 -dithiolate Bonding in Ru 2 M Derivatives of Cp*Ru III (tpdt) (HMB = η 6 -C 6 Me 6 ; Cp* = η 5 -C 5 Me 5 ; M = Cu I , Ag I,II , Au I ; tpdt = 3-thiapentane-1,5-dithiolate)

The reaction of [(HMB)Ru II (η 3 -tpdt)] ( 1: HMB = η 6 -C 6 Me 6; tpdt = S(CH 2 CH 2 S - ) 2 ) with [Cu(MeCN) 4 ]PF 6, AgPF 6, and (PPh 3 )AuCl gave the annular species [{(HMB)Ru II (μ 3 -η 1:η 1:η 3 -tpdt)} 2 (M) 2 ] 2+ [ 3: M = Cu I; 3A: (M) 2 = Cu I, Cu I (MeCN); 4: M = Ag I; 6: M = Au I ], isolated as PF 6 salts in high yields. Complex 6 was formed in a reversible process with [{(HMB)Ru II (μ-η 1:η 3 -tpdt)}(AuPPh 3 )] + ( 5 ) involving dissociation/association of PPh 3 . Similar reactions of [Cp*Ru III (η 3 -tpdt)] ( 2: Cp* = η 5 -C 5 Me 5 ) gave, respectively, the cationic metal−metal bonded Ru 2 M complexes [{Cp*Ru(μ-η 2:η 3 -tpdt)} 2 M] n + ( 7: M = Cu I, n = 1; 8: M = Ag II, n = 2) and [{Cp*Ru(μ-η 1:η 3 -tpdt)}(AuPPh 3 )] + ( 9 ), isolated as PF 6 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-η 6 -(S(CH 2 ) 2 S(CH 2 ) 2 SAuPPh 3 ) 2 }] 2+ ( 10 ), containing a μ-S 2 bridge, and [{Cp*Ru(μ 3 -η 1: η 1:η 3 -tpdt)}(AuPPh 3 ) 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 CH 2 Cl 2 . 7 and 8 could be oxidized and reduced in several one-electron steps to form moderately stable species with extensive electron delocalization between the Ru 2 M atoms. An EPR spectrum of 8, a Ag(II) (d 9 ) species, was obtained at liquid He temperatures.