Metal(II)-promoted hydrolysis of pyridine-2-carbonitrile to pyridine-2-carboxylic acid.: The structure of [Cu(pyridine-2-carboxylate)2]•2H2O

Pyridine-2-carbonitrile (2-CNpy) undergoes Cu(II) or Co(II)-promoted hydrolysis to pyridine-2-carboxamide (piaH) and/or pyridine-2-carboxylic acid (pycH). the pathway of pycH formation depends on the presence of 2-amino-2-hydroxymethyl-1,3-propanediol (AL(1)) and on the central atom. In the absence of AL(1) Co(II) or Cu(II) ions mediate piaH formation under mild reaction conditions in the first hydrolytic step. Cu(II) ions assist in piaH transformation to pycH by subsequent reflux. In the presence of AL(1) and Co(II), a Co(II) complex containing pyoxaL(1) (2-(2-pyridinyl)-4,4-bis(hydroxymethyl)-2-oxazoline) is formed in the first stage, subsequent decomposition of pyoxaL(1) under the reflux yields pycH. Under similar conditions, no solid Cu(II) complex with pyoxaL(1) can be isolated, but a Cu(Il) complex with coordinated pyc(-) anions precipitates from the reaction mixture. The synthesis, spectral and magnetic properties of the complexes [Co(H2O)(2) (piaH)(2)]Cl-2,[CO(H2O)(2)(pyc)(2)]. 2H(2)O, [Cu(H2O)(2)(piaH)(2)]Cl2, [Cu(pyc)(2)] and [Cu(pyc)(2)]. 2H(2)O, including the structure determination of the latter one, are described. (C) 1998 Elsevier Science Ltd. All rights reserved.