Flash Communication: Planar W2Ge2 Cluster with NHC–Hydrogermylyne Ligands

A hydrogermylyne-bridged W2Ge2 cluster 1, stabilized by N-heterocyclic carbene (NHC), was synthesized by the reaction of a hydrido(hydrogermylene) complex with an excess of 1,3,4,5-tetramethylimidazol-2-ylidene (MeIMe). X-ray diffraction analysis revealed a planar and rhombic four-membered W2Ge2 ring framework with a relatively short diagonal Ge···Ge distance (∼2.74 Å). Each Ge atom bears a Ge–H bond, representing the first example of this bonding motif. The extremely high-field-shifted 1H NMR signal (1.59 ppm) of the Ge–H proton and DFT calculations including QTAIM and NICS-rate analyses suggest a significant electron delocalization over the W2Ge2 ring.