The synthesis of tripodal nitrogen donor ligands and their characterization as Pd IIMe 2 and Pd IIIMe derivatives

Abstract

New tripod ligands containing pyridin-2-yl (py), N-methylimidazol-2-yl (mim), and pyrazol-1-yl (pz) groups have been made by addition of 2-bromopyridine to deprotonated (py)(mim)CH 2 or (mim) 2CH 2 to form (py) 2(mim)CH and (py) (mim) 2CH, or by simple condensation reactions of (pz) 2CO with (mim)CHO or (py)CHO to form (pz) 2(mim)CH and (pz) 2(py)CH. The ligands may have general application in coordination and organometallic chemistry, especially bis(pyrazol-1-yl)(pyridin-2-yl)methane [(pz) 2(py)CH], which can be readily synthesized and is an unsymmetrical tripod closely related to (pz) 3CH and (py) 3CH. Dimethylpalladium(II) and methyl(iodo)palladium(II) complexes of the ligands have been isolated, and compared with complexes of (pz) 3CH, (py) 3CH, and (pz) 4C.