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 ? THF] followed by the addition of ethane-1,2-dithiol led to the formation of an EPR active bimetallic vanadium thiolato complex (Cp*V){μ-(SCH₂CH₂S)-κ²S,S′)₂{V(SCH₂CH₂S-SH)}] ( 2 ). In complex 2 , two ethane-1,2-dithiolato ligands are symmetrically coordinated to two vanadium atoms through μ-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 ? THF] yielded heterobimetallic thiolato complex (Cp*Ta){μ-(SCH₂CH₂S)-κ²S,S′}{μ-(SCH₂CH₂S?CH₂(CH₃)S)κ²S′′ : κ¹S-′′′′ : κ¹S′′′′′}{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.