Copper complexes with (2,7-Di-tert-butylfluoren-9-ylidene) methanedithiolate: Oxidatively promoted dithioate condensation

Article abstract of DOI:10.1002/ejic.200500613

The reaction of [Cu(NCMe)₄]PF₆ with piperidinium 2,7-di-tert-butyl-9H-fluorene-9-carbodithioate (pipH)[S₂C(tBu-Hfy)] (1; tBu-Hfy = 2,7-di-tert-butylfluoren-9-yl), affords [Cu_n{S ₂C(tBu-Hfy)}_n] (2), which reacts with various P ligands to give [Cu{S₂C(tBu-Hfy)}L₂] [L = PPh₃ (3a), PCy₃ (3b), PiPr₃ (3d); L₂ = 1,1′-bis(diphenylphosphanyl)ferrocene (dppf, 3c), bis(diphenylphosphanyl) methane (dppm, 3e)]. Compounds 3a-c react with atmospheric oxygen and moisture in the presence of NEt₃ to give the dinuclear complexes [Cu ₂{[SC=(tBu-fy)]₂S}L₂] [tBu-fy = 2,7-di-tert-butylfluoren-9-ylidene; L = PPh₃ (4a), PCy₃ (4b); L₂ = dppf (4c)], which contain a new dithiolato ligand formally resulting from the condensation of two dithioato ligands with loss of a sulfide ion and two protons. Neutral Cu^I dithiolate complexes of the type [Cu₄{S₂C=(tBu-fy)}₂L₄] [S ₂C=(tBu-fy) = [2,7-di-tert-butylfluoren-9-ylidene)methanedithiolate; L = PPh₃ (5a), P(C₆H₄OMe-p)₃ (5b), PiPr₃ (5d) or L₂ = dppf (5c)] were obtained by treating 1 with [Cu(NCMe)₄]PF₆, the corresponding phosphane, and piperidine in a 1:2:2:1 molar ratio. The reaction of 1 with Cu(ClO ₄)₂·6H₂O and (Pr₄N)OH in a 2:1:2 molar ratio gives the Cu^II complex (Pr₄N) ₂[Cu{S₂C=(tBu-fy)}₂] [(Pr₄N) ₂6], which readily oxidizes to the Cu^III complex Pr ₄N[Cu{S₂C=(tBu-fy)}₂] (Pr₄N7) in the presence of atmospheric oxygen and moisture. The salt PPN7 [PPN⁺ = (Ph₃P)₂N⁺] was obtained from 1, CuCl ₂·2H₂O, PPNCl, and piperidine in a 2:1:1:2 molar ratio under aerobic conditions. The crystal structures of 3a, 3c·CH ₂Cl₂, 4a·4Me₂CO, and 4c·CH ₂Cl₂ have been determined by X-ray diffraction studies. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.