Double heterocumulene metathesis of cyclic bis(trimethylsilylamido)stannylenes and tethered bimetallic bisamidinates from the resulting alpha,omega-biscarbodiimides

Reaction of 2 equiv of tert-butylisocynnate with the cyclic bisamidostannyl enes, 3a and 3b, provides the alpha,omega-biscarbodiimides, (BuN)-Bu-t=C=N( CH2)(n)N=C=N-t-Bu (2a and 2b; n = 3 and 4, respectively) in high yield. Rea ction of 2b with 2 equiv of (eta(5)-C5H5)TiMe3 results in clean formation o f the tethered bimetallic bisamidinate represented by meso/rac-1. The cryst al structures of 3b and rac-1 are reported.