Synthesis and crystallographic characterization of a mononuclear cobalt(III) complex possessing both thiolate and thioether donors: reactivity of an thiolate-bridged pentanuclear Co2Ag3 complex with iodomethane

Abstract

Treatment of an S-bridged pentanuclear AgI 3CoIII 2 complex, [Ag3{Co(L)}2]3+ [L 3– = N(CH2NHCH2CH2S−)3], in which two tris(thiolate)-type mononuclear CoIII units ([Co(L)]) are bridged by three AgI ions through S atoms, with iodomethane (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 thiolate groups in [Co(L)] are methylated while one thiolate group remains unreacted. Although a total of eight stereoisomers are possible for [Co(LMe2)]2+, only a pair of enantiomers {Λ RR - and Δ SS -[Co(LMe2)]2+} are selectively formed. In the crystal, the complex cations and the PF6 − 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.