Unique Rearrangement of an Oxycarbyne Complex: Synthesis and Structure of Novel Diborane(4)yl Complexes

Nucleophilic attack of a carbonyl oxygen atom of the complexes K[(eta(5)-C(5)H(5))M(CO)(3)] (M=Mo, W) on each boron center gave the oxycarbyne complexes 1. These novel products undergo a unique type of rearrangement with quantitative formation of the diborane(4)yl complexes 2. Complex 2 (M=Mo) is the first structurally characterized boryl complex with a Mo-B bond (see structure).