Reactivity of CS₂ - syntheses and structures of transition-metal species with dithioformate and methanedithiolate ligands

Abstract

The syntheses and structural characterization of the CS₂–metal complexes [(η⁵-C₅Me₅M)(η²-S₂CH₂)(η³-S₂CH)] (1: M = Mo; 2: M = W), which feature partially and fully reduced CS₂, are reported. In addition, the cis and trans isomers of the dimetallic (sulfido)molybdenum complexes [(η⁵-C₅Me₅Mo)₂ (µ-S₂CH₂S)₂] (3-cis and 4-trans) are described. The [Mo₂S₄] cores of 3-cis and 4-trans represent paddlewheel-like arrays. All the new compounds were characterized in solution by mass spectrometry, IR spectroscopy, and ¹H and ¹³C NMR spectroscopy. Their structural architectures were established by X-ray crystallographic analysis. Quantum-chemical calculations by DFT methods on the model compounds 1′–4′-trans showed good agreement with the experimentally observed structural parameters. The large HOMO–LUMO (HOMO = highest occupied molecular orbital, LUMO = lowest unoccupied molecular orbital) gaps are consistent with the high thermodynamic stabilities of these complexes. Further, the presence of short metal–metal cross-cluster bonds in the X-ray structures of 3-cis and 4-trans is supported by natural bond order (NBO) calculations.