Theoretical Investigation of Obtaining Compounds with Planar Tetracoordinate Carbons by Frustrated Lewis Pairs.

Ten derivatives of 2-borabicyclo[1.1.0]but-1(3)-ene (1a-1j) with different degrees of frustration have been investigated using density functional theory. Moreover, 1a-1j as Lewis bases were used to form Lewis adducts C3X2BYH/B(C6F5)3 (2a-2j) with Lewis acid B(C6F5)3. Optimized geometries and the thermodynamic properties of giving the Lewis adducts C3X2BYH/B(C6F5)3 reveal that 2a-2j are frustrated Lewis pairs (FLPs). Their reactivity of activating H2 and HF show that 2a-2j are unfavorable to heterolytically cleave H2, whereas 2c-2j can cleave HF to form C3X2BYHFB(C6F5)3. In addition, we found the structures of C3X2BYH in C3X2BYHFB(C6F5)3 contained a planar tetracoordinate carbon (ptC). Therefore, a new method of obtaining main group element compounds with ptC by using FLPs was presented.