A bis(silylene)pyridine pincer ligand can stabilize mononuclear manganese(0) complexes: facile access to isolable analogues of the elusive d(7)-Mn(CO)(5) radical

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, {κ(3)-[SiNSi]Mn(dmpe)} 4 (dmpe = (Me(2)P)(2)C(2)H(4)), 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 κ(2)-[SiNSi]Mn(CO)(3) (5) and κ(3)-[SiNSi]Mn(CNXylyl)(2)(κ(1)-dmpe) (6), respectively. Remarkably, the stabilization of Mn(0) in the coordination sphere of the [SiNSi] ligand favors the d(7) 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.