Tridentate NacNac Stabilized Tin and Nickel Complexes: Access to a Monomeric Nickel Hydride and Its Catalytic Application.

The transmetalation reaction of picolyl-supported tridentate nacnac germylene monochloride [2,6- i Pr 2 -C 6 H 3 NC(Me)CHC(Me)NH(CH 2 py)]GeCl ( 1 ) (py = pyridine) with SnCl 2 results in an analogous stannylene chloride ( 2 ). The three-coordinated stannylenium cation [{2,6- i Pr 2 -C 6 H 3 NC(Me)CHC(Me)NH(CH 2 py)}Sn] + with SnCl 3 - as a counteranion ( 3 ) has been generated through the abstraction of chloride ligand from 2 using an additional equivalent of SnCl 2 . Instead of forming a donor-acceptor complex, 2 undergoes a facile redox transmetalation reaction with Ni(COD) 2 (COD = cyclooctadiene) and CuCl to afford analogous nickel and copper complexes [2,6- i Pr 2 -C 6 H 3 NC(Me)CHC(Me)NH(CH 2 py)]MCl [M = Ni ( 4 ) and Cu ( 5 )]. The reactions of 4 with potassium tri- sec -butylborohydride (commonly known as K-selectride) and AgSbF 6 provide access to monomeric Ni(II) hydride, [2,6- i Pr 2 -C 6 H 3 NC(Me)CHC(Me)NH(CH 2 py)]NiH ( 6 ) and a Ni(II) cation, [{2,6- i Pr 2 -C 6 H 3 NC(Me)CHC(Me)NH(CH 2 py)}Ni][SbF 6 ] ( 7 ), respectively. 6 was found to be an effective catalyst for the hydroboration of amides.