The insertion of carbene ligands into Ge-N (three examples) and Si-N (one example) bonds has been achieved for the first time by treating Fischer carbene complexes (M=W, Cr) with bulky amidinatotetrylenes (E=Ge, Si). These reactions, which start with a nucleophilic attack of the amidinatotetrylene heavier group 14 atom to the carbene C atom, proceed through a stereoselective insertion of the carbene fragment into an E-N bond of the amidinatotetrylene ENCN four-membered ring, leading to [M(CO) L] derivatives in which L belongs to a novel family of tetrylene ligands comprising an ECNCN five-membered ring.

The silylenes Si(tBu2bzam)R (tBu2bzam=N,N′‐bis(tertbutyl)benzamidinate; R=mesityl, CH2SiMe3) attack the Ccarbene atom of the Fischer alkynyl(ethoxy)carbene complex [W(CO)5{C(OEt)C2Ph}] to give, after a striking rearrangement, zwitterionic σ‐allenyl complexes in which the original carbene C atom forms part of the allene C3 fragment and also of a Si‐C‐N‐C‐N five‐membered ring after insertion into a Si−N bond of the original amidinatosilylene. These remarkable allenyl products, which contain two stereogenic groups, are selectively formed as single diastereomers.

OsH6(PiPr3)2 has been used to selectively activate C–H, O–H, and C–C sigma bonds in nucleobases and nucleosides, including derivatives of 6-phenylpurine and 4-phenylpyrimidine, leading to cyclometalated mononuclear Os–trihydride complexes, in excellent yields and as single products. Additionally, OsH6(PiPr3)2 promotes the efficient dehydrogenative decarbonylation of primary alcohols in nucleosides having unprotected sugar moieties. The incorporation of OsH2Cl2(PiPr3)2 in the structure of cyclometalated Ir­(III) and Rh­(III) half-sandwich complexes derived from nucleosides allows the preparation of a class of heterobimetallic bioorganometallic complexes having at least one M–C bond. These methodologies could be used in the future as a way for the orthogonal functionalization of oligonucleotides.