Bispyridyl- and Bisquinolylmenthanes. NMR-based Charge Mapping of the Carbanions and Metal Ligand Properities

Nmr evidence is obtained for mixtures of geometrical stereoisomers of carbanions in DMSO solution of bls(4-)-and bis(2-pyridyljmethane (1) and (2).bis(2pyridyi)acetonitrile (3).and bis(2quinolyl)methane (4).When incorporated into n-chargelshift relationships the ' 3 ~ and ''N nmr data provide access to charge demands cx of the heterocycles, that is the fraction of n-charge withdrawn by the rings from the carbanionic carbon.Compoundsi3)andi4)behave as ligands LH, whose anions L' produce neutral chelates with divalent metal Ions (Met = 2n2+, pd2+) W l h Met = co2+, cu2+, ~n ' + the ligand LH 3 affords the dimer L? The present paper reports the preparation of the carbanions of bis(4-pyridy1)rnethane (I), bis(2-pyridy1)methane (21, bis(2-pyridyl)acetonitrile (3), and bis(2-quinoly1)methane (4), and the study of their Dedicated to Professor Rolf HUlSGEN on the occasion of his 75th birthday