Synthesis, structure and reactivity of aminomethylpyridine zinc dihalides

Zinc dichloride reacts with aminomethylpyridine (AMP) to the corresponding 1:1 adduct 1, whereas ZnBr2 forms an ionic 1:2 complex of the type [(AMP)(2 )ZnBr](+) Br- 2, which loses one neutral coligand upon heating in Me-C(O)OE t to yield nearly insoluble (AMP)ZnBr2 3. The condensation reaction of thes e compounds with acetone yields propylideneaminomethyIpyridine zinc dichlor ide (4) and dibromide (5), respectively. The reaction of ZnI2 with AMP and acetone gives propylideneaminomethylpyridine zinc dichloride (6) in quantit ative yield. The structures of 3, 4, and 6 confirm the linear relationship between the Zn-N distance and the X-Zn-X angle in compounds of the type (L- 2)ZnX2 with L-2 being a bidentate amino base, whereas short Zn-N bonds enfo rce small X-Zn-X angles. Compound 2 consists of separated ions in the solid state with a five coordinate zinc atom in a distorted kigonal bipyramidal coordination sphere.