Using the potentially tridentate N,N’-bis(N-heterocyclic silylene)pyridine [SiNSi] pincer-type ligand, 2,6-N,N’-diethyl-bis[N,N’-di-tert-butyl(phenylamidinato)silylene] diaminopyridine, led to the first isolable bis(silylene)pyridine-stabilized manganese(0) complex, {к3-[SiNSi]Mn(dmpe)} 4 (dmpe = (Me2P)2C2H4), which represents an isolobal 17 VE analogue of the elusive Mn(CO)5 radical. The compound is accessible through the reductive dehalogenation of the corresponding dihalido (SiNSi)Mn(II) complexes 1 (Cl) and 2 (Br) with potassium graphite. Exposing 4 towards the stronger π-acceptor ligands CO and 2,6-dimethylphenyl isocyanide afforded the related Mn(0) complexes к2-[SiNSi]Mn(CO)3 (5) and к3-[SiNSi]Mn(CNXylyl)2(к1-dmpe) (6), respectively. Remarkably, the stabilization of Mn(0) in the coordination sphere of the [SiNSi] ligand favors the d7 low-spin electronic configuration, as suggested by EPR spectroscopy, SQUID measurements and DFT calculations. The suitability of 4 acting as a superior pre-catalyst in regioselective hydroboration of quinolines has also been demonstrated.

https://pubs.rsc.org/en/content/articlelanding/2022/sc/d2sc03352f