Double Heterocumulene Metathesis of Cyclic Bis(trimethylsilylamido)stannylenes and Tethered Bimetallic Bisamidinates from the Resulting α,ω-Biscarbodiimides

Reaction of 2 equiv of tert -butylisocyanate with the cyclic bisamidostannylenes, 3a and 3b, provides the α,ω-biscarbodiimides, t BuN C N(CH 2 ) n N C N t Bu ( 2a and 2b; n = 3 and 4, respectively) in high yield. Reaction of 2b with 2 equiv of (η 5 -C 5 H 5 )TiMe 3 results in clean formation of the tethered bimetallic bisamidinate represented by meso / rac - 1 . The crystal structures of 3b and rac - 1 are reported.