Synthesis and reactions of coordinatively unsaturated 16-electron chalcogenolate complexes, Ru(EAr) 2(η6-arene) and cationic binuclear chalcogenolate complexes, [(η6-arene) Ru(μ-EPh) 3Ru( η6-arene) ]PF6

Article abstract of DOI:10.1016/S0022-328X(97)00378-1

Coordinatively unsaturated 16-electron ruthenium-selenolate complexes (η⁶-arene)Ru(Se-2,4,6-C₆H₂Me₃)₂ [arene = p-CH₃C₆H₄(CHMe₂) (5b), C₆Me₆ (5c)] have been prepared by treating [((η⁶-arene)RuCl₂]₂ (1) with sodium salt of 2,4,6-trimethylphenyl-selenolate in methanol. The complexes 5 are compared with the thiolate complexes such as (η⁶-arene)Ru(SAr)₂ [SAr = 2,6-dimethylbenzenethiolate (2), SAr = 2,4,6-tri(isopropyl)benzenethiolate (3), (SAr)₂ = 1,2-benzenedithiolate (4); arene = C₆H₆ (a), p-CH₃C₆H₄(CHMe₂) (b), C₆Me₆ (c)], which have been recently prepared by us. However, the tellurolate analog has not been obtained in similar manner. These selenolate complexes are dark green, being ascribed to the LMCT band [pπ(Se) → dπ * (Ru)]. The absorption bands of 5 are red-shifted compared to the thiolate complexes. In contrast to the bulky substituted chalcogenolate ligand system, the reaction of 1 with PhENa followed by the addition of KPF₆ resulted in the formation of the cationic binuclear chalcogenolate complexes [(ηη⁶-arene)Ru(μ-E-Ph)₃Ru(η⁶-arene)](PF⁶) [E = Se (7), E = Te (8); arene = p-CH₃C₆H₄(CHMe₂) (b), C₆Me₆ (c)]. Reactions of the 16-electron thiolate and selenolate complexes with σ-donor molecules such as DMSO, hydrazine and ammonia along with some electrophiles were investigated. DMSO can coordinate with the thiolate complex 2a to give a DMSO adduct of 9, which was characterized spectroscopically and crystallographically. The strength of complexation of hydrazine and ammonia to the thiolate and selenolate complexes 2, 3, 4c and 5 depends on the effective electron deficiency of the ruthenium supported by η⁶-arene ligand and two chalcogenolate ligands. Two new hydrazine complexes (η⁶-C₆H₆)Ru(η¹-NH₂NH₂)(S-2,6-C₆H₃Me₂)₂ (10a) and [(η⁶-C₆Me₆)Ru(S₂C₆H₄)]₂( μ-NH₂NH₂) (16) were crystallographically characterized. The observed two different coordination modes, mononuclear η¹-hydrazine and binuclear μ-hydrazine, were the results of the combined steric effect of the arene and the thiolate coligands as well as the NH ... S hydrogen bonding.