Synthesis and crystallographic characterization of a mononuclear cobalt(III) complex possessing both thiol-ate and thio-ether donors: reactivity of an thiol-ate-bridged penta-nuclear Co2Ag3 complex with iodo-methane.

Abstract

Treatment of an S-bridged penta-nuclear AgI3CoIII2 complex, [Ag3{Co(L)}2]3+ [L3- = N(CH2NHCH2CH2S-)3], in which two tris-(thiol-ate)-type mononuclear CoIII units ([Co(L)]) are bridged by three AgI ions through S atoms, with iodo-methane (CH3I) gave a new CoIII mononuclear complex, [Co(LMe2)]2+ [LMe2- = N(CH2NHCH2CH2S-)(CH2NHCH2CH2SCH3)2], systematic name: {2-[(bis{[2-(methylsulfanyl)ethyl]aminomethyl}aminomethyl)amino]ethanethiolato}cobalt(III) bis(hexafluoridophosphate). This cationic complex was crystallized with PF6- anions to form the title compound, [Co(LMe2)](PF6)2. In the [Co(LMe2)]2+ cation, two of three thiol-ate groups in [Co(L)] are methyl-ated while one thiol-ate group remains unreacted. Although a total of eight stereoisomers are possible for [Co(LMe2)]2+, only a pair of enanti-omers {Λ RR - and Δ SS -[Co(LMe2)]2+} are selectively formed. In the crystal, the complex cations and the PF-6- anions are connected through weak N-H⋯F, C-H⋯F and C-H⋯S hydrogen bonds into a three-dimensional structure. Two F atoms in one PF6 anion are disordered over two sets of sites with refined occupancies of 0.61 (4) and 0.39 (4) and two F atoms in the other PF6- anion are disordered over two sets of sites with occupancies of 0.5.