N-nacnac Stabilized Tetrelenes: Formation of an N,P-Heterocyclic Germylene via C-C Bond Insertion

The use of an amino-functionalized beta-diketiminate (N-nacnac) ligand in low-valent germanium chemistry is reported, with a view to comparison with conventional nacnac systems. Transmetallation of the N-nacnac ligand from lithium allows access to a versatile chlorogermylene system, and subsequent substituent exchange processes are used to generate related hydrido-, and phosphaketenyl-germylenes. The latter undergoes photolytically-induced cleavage of the P-CO bond to yield an unusual imine-coordinated N,P-heterocyclic germylene. On the basis of DFT calculations this transformation is proposed to occur via concerted attack by the electron-rich carbon-carbon bond of the N-nacnac backbone accompanying CO loss, rather than via the generation of a free phosphinidene.