Synthesis and Crystal Structure of a Tetranuclear Molybdenum(II) Silylamido Cluster

Treatment of molybdenum(II) chloride with the difunctional silylamide Li₂Me₂Si(NPh)₂ led to the formation of the tetranuclear cluster compound Mo₄{Me₂Si(NPh)₂}₄]. According to the X-ray crystal structure determination, the central core of the cluster consists of four molybdenum atoms in a nearly rectangular arrangement. There are two μ₄-κ-N,N,N',N'-Me₂Si(NPh)₂^2– ligands capping the Mo₄ rectangle and two μ₂-Me₂Si(NPh)₂^2– ligands located at opposite edges. The alternating Mo–Mo distances of 218.1(1) and 279.5(1) pm indicate the presence of a cyclobutadiyne type cluster with alternating Mo–Mo triple and single bonds.