[(Ln)Ru{η3-(tpdt)}] Complexes as Dithiolate Donors to Group 10 Metal Centers:  Synthetic, Single-Crystal X-ray Diffraction and Electrochemical Studies {Ln = η6-C6Me6 (HMB) and η5-C5Me5 (Cp); tpdt = S(CH2CH2S)2}

• Published in: Organometallics 2004-12, Vol.23 (26), p.6108-6115
• Main Authors: Shin, Richard Y. C, Tan, Geok Kheng, Koh, Lip Lin, Goh, Lai Yoong, Webster, Richard D
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om049407t

Trinuclear mixed metal cationic complexes of Ru−Pd, [{(Ln)Ru(μ-η2:η3-tpdt)}2Pd]2+ (4A, L n = HMB; 8, L n = Cp*), and of Ru−Pt, [{(Ln)Ru(μ-η2:η3-tpdt)}2Pt]2+ (5B, Ln = HMB; 9, Ln = Cp*), containing bare bridging M(II) (M = Pd, Pt) centers, are formed from the reaction of [(HMB)RuII(η3-tpdt)] (1) and [Cp*RuIII(η3-tpdt)] (2) (tpdt ≡ S(CH2CH2S)2) with Pd(MeCN)2Cl2 (or PdCl2) and PtCl2, respectively. With Pt(PPh3)2Cl2, both 1 and 2 displace the chloro ligands, thus forming dinuclear complexes [{(HMB)Ru(μ-η2:η3-tpdt)}{Pt(PPh3)2}]2+ (6) and [{(Cp*)Ru(μ-η2:η3-tpdt)}{Pt(PPh3)2}]2+ (10), in which Pt is coordinated to two thiolate atoms and two PPh3 ligands in a four-coordinate planar geometrical environment. X-ray diffraction analyses show that the arene complexes 4A and 5B also possess four-coordinate planar geometry at the central metal atom. In the Cp* complexes, the central MS4 moiety is tetrahedral for M = Pd, but planar for M = Pt, both metal centers being metal−metal bonded to the peripheral Ru atoms, presumably as dictated by the demands of the 18e rule. Electrochemical studies show that complexes 8 and 9 and the Ni analogues of 4A and 8, viz., 3 and 7, respectively, can be reduced in two one-electron steps and oxidized by one electron. The one-electron reduced and oxidized species are paramagnetic, and EPR spectra were obtained of the species in frozen solutions. The electrochemical data indicate that the Pd- and Pt-containing compounds show intermediate electron delocalization between the two Ru atoms, indicative of a class II system, while the Ni-containing analogues show extensive electron delocalization between the Ru atoms, indicative of a class III system.