Planar Tetracoordinate Carbon in Organoboron Compounds: ab initio Computational Study

Ab initio MP2(full)/6-311++G** calculations revealed that 1,2-diboraspiro[2.2]pent-4-ene (11) and two of its isomers 14 and 15 possess stable structures with planar tetracoordinate carbon. These compounds and some of their derivatives, 21 and 22, can be regarded as the first computationally found organoboron compounds with the planar tetracoordinate carbon.