Synthesis, structures, and properties of group 9- and group 10-group 6 heterodinuclear nitrosyl complexes

The reaction of the group 9 bis(hydrosulfido) complexes [Cp*M(SH)(2)(PMe3)] (M = Rh, Ir; Cp* = eta(5)-C5Me5) with the group 6 nitrosyl complexes [CP*M'Cl-2(NO)] (M' = Mo", W) in the presence of NEt3 affords a series of bis(sulfido)bridged early-late heterobimetallic (ELHB) complexes [CP*M(PMe3)(mu-S)(2)M'(NO)Cp*] (2a, M = Rh, M' = Mo; 2b, M = Rh, M' = W; 3a, M = Ir, M' = Mo; 3b, M = Ir, M' = W). Similar reactions of the group 10 bis(hydrosulfido) complexes [M(SH)(2)(dppe)] (M = Pd, Pt; dppe = Ph2P(CH2)(2)PPh2), [Pt(SH)(2)(dppp)] (dppp = Ph2P(CH2)(3)Pph(2)), and [M(SH)(2)(dpmb)] (dpmb = o-C6H4(CH2PPh2)(2)) give the group 10-group 6 ELHB complexes [(dppe)M(mu-S)(2)M'(NO)Cp*] (M = Pd, Pt; M'= Mo, W), [(dppp)Pt(mu-S)(2)M'(NO)Cp*] (6a, M'= Mo; 6b, M'= W), and [(dpmb)M(mu-S)(2)M'(NO)Cp*] (M = Pd, Pt; M' = Mo, W), respectively. Cyclic voltammetric measurements reveal that these ELHB complexes undergo reversible one-electron oxidation at the group 6 metal center, which is consistent with isolation of the single-electron oxidation products [Cp*M(PMe3)(mu-S)(2)M'(NO)Cp*][PF6] (M = Rh, Ir; M' = Mo, W). Upon treatment of 2b and 3b with ROTf (R = Me, Et; OTf = OSO(2)CFA the 0 atom of the terminal nitrosyl ligand is readily alkylated to form the alkoxyimido complexes such as [Cp*Rh(PMe3)(mu-S)(2)W(NOMe)Cp*][OTf]. In contrast, methylation of the Rh-, Ir-, and Pt-Mo complexes 2a, 3a, and 6a results in S-methylation, giving the methanethiolato complexes [Cp*M(PMe3)(mu-SMe)(mu-S)Mo(NO)Cp*][BPh4] (M = Rh, Ir) and [(dppp)Pt(mu-SMe)(mu-S)Mo(NO)Cp*][OTf], respectively. The Pt-W complex 6b undergoes either S- or O-methylation to form a mixture of [(dppp)Pt(mu-SMe)(mu-S)W(NO)Cp*][OTf] and [(dppp)Pt(mu-S)(2)W(NOMe)Cp*][OTf]. These observations indicate that O-alkylation and one-electron oxidation of the dinuclear nitrosyl complexes are facilitated by a common effect, i.e., donation of electrons from the group 9 or 10 metal center, where the group 9 metals behave as the more effective electron donor.