Reversible Coupling of Germylone with Isocyanates.

The germylone dimNHCGe (5, dimNHC=diimino N‐heterocyclic carbene) undergoes a [2+2] cycloaddition with isocyanates RNCO (R=4‐tolyl or 3,5‐xylyl) to furnish novel alkyl carboxamido germylenes 7 (R=4‐tolyl) and 8 (R=3,5‐xylyl), featuring a C−C bond between the former carbene carbon and the isocyanate moiety. Heating a mixture of 8 with 4‐tolyl isocyanate to 100 °C results in isocyanate metathesis, demonstrating reversible C−C bond formation on the reduced germanium compound. DFT calculations suggest that this process occurs via the reductive dissociation of isocyanate from 8 that regenerates the parent Ge(0) compound 5. [ABSTRACT FROM AUTHOR]