Syntheses, Structures, and Electronic Properties of Mono- and Bimetallic Thiolato Complexes Containing Unusual Coordination Modes of Thiolato Ligands

Synthesis, bonding and chemistry of mono- and bimetallic complexes supported by chelating thiolato ligands have been established. Treatment of [Cp*VCl2](3) (1) with [LiBH4 center dot THF] followed by the addition of ethane-1,2-dithiol led to the formation of an EPR active bimetallic vanadium thiolato complex [(Cp*V){mu-(SCH2CH2S)-kappa S-2,S')(2){V(SCH2CH2S-SH)}] (2). In complex 2, two ethane-1,2-dithiolato ligands are symmetrically coordinated to two vanadium atoms through mu-S atoms. Interestingly, when similar reactions were carried out with heavier group 5 metal precursors, such as [Cp*NbCl4] (3 a), it afforded monometallic thiolato complex [Cp*Nb(SCH2CH2S)(SCH2CH2S-CH2S)] (4 a). On the other hand, the Ta-analogue [Cp*TaCl4] (3 b) yielded thiolato species [Cp*Ta(SCH2CH2S)(SCH2CH2S-CH2S)] (4 b) and [Cp*Ta(SCH2CH2S) (SCH2CH2S-S)] (5). In complexes 4 a and 4 b, one ethane-1,2-dithiolato and one trithiolato ligand are coordinated to Nb and Ta centers, respectively. Whereas, in complex 5, one ethane-1,2-dithiolato and one 2-disulfanylethanethiolato is coordinated to the Ta center. Moreover, the photolytic reaction of 5 with [Mo(CO)(5) center dot THF] yielded heterobimetallic thiolato complex [(Cp*Ta){mu-(SCH2CH2S)-kappa S-2,S '}{mu-(SCH2CH2S-CH2(CH3)S)kappa S-2 '' : kappa S-1-'''' : kappa S-1 '''''}{Mo(CO)(3)}] (6). All the complexes have been characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction studies. Further, computational analyses were performed to provide an insight into the bonding of these complexes.