First-Row Transition Metal Complexes of a Phosphine-Silylene-Based Hybrid Ligand.

We have prepared two new silylene-phosphine-based hybrid ligands Si{N(R)C 6 H 4 (PPh 2 )}{PhC(N t Bu) 2 } [R = TMS {trimethylsilyl} ( 1 ) and TBDMS { tert -butyldimethylsilyl} ( 2 )], which possess two donor sites. Furthermore, the treatment of the bidentate ligand 1 with base metal halides {FeBr 2 , CoBr 2 , NiCl 2 ·dme [nickel chloride(II) ethylene glycol dimethyl ether]} and 2 with NiBr 2 ·dme [nickel bromide(II) ethylene glycol dimethyl ether] afforded four-coordinate six-membered metal complexes 3-6 , respectively, which feature coordination from both Si(II) and P(III) sites. Subsequently, complexes 3 [(FeBr 2 )Si{N(SiMe 3 )C 6 H 4 (PPh 2 )}{PhC(N t Bu) 2 }], 4 [(CoBr 2 )Si{N(SiMe 3 )C 6 H 4 (PPh 2 )}{PhC(N t Bu) 2 }], 5 [(NiCl 2 )Si{N(SiMe 3 )C 6 H 4 (PPh 2 )}{PhC(N t Bu) 2 }], and 6 [(NiBr 2 )Si{N(Si t BuMe 2 )C 6 H 4 (PPh 2 )}{PhC(N t Bu) 2 }] are studied for their redox and magnetic properties with the help of UV-vis spectroscopy, cyclic voltammetry, SQUID magnetometry, and theoretical calculations. Complexes 3-6 were found to display a paramagnetic behavior. All the compounds are well established by single-crystal X-ray diffraction studies.