摘要
In contrast to the readily accessed mid-valent molybdenum precursors, trivalent tungsten compounds as good synthons are rare. The most commonly used trivalent ditungsten species, NaW 2 Cl 7 (THF) 5 , for the synthesis of the triply W − W bonded compounds of the type W 2 X 6 (X = bulky anionic ligand) can no longer be prepared because it is obtained from Na/Hg reduction of WCl 4 , and the use of mercury is banned. In this work, we report the characterization of a useful ditungsten(III) complex W 2 (μ-Cl) 2 Cl 4 (κ 2 -DME) 2 (2) (DME = 1,2-dimethoxyethane) to replace NaW 2 Cl 7 (THF) 5 . The efficient reduction of the monomeric W(IV) compound WCl 4 (DME) (1) with granular Sn in DME gives 2 in a 97% isolated yield. 2 is a diamagnetic species based on SQUID magnetometry, and its formulation was established by single-crystal X-ray crystallography. The structure of 2 shows an edge-sharing bioctahedral (ESBO) conformation with overall C i symmetry and the W − W bond length is 2.6443 (6) Å. Density functional theory (DFT) calculations suggest a σ 2 π 2 δ* 2 ground state configuration corresponding to the W − W single bond.