Innersphere transformations of pyridine-2-carbonitrile mediated by copper(II), cobalt(II) and nickel(II). Crystal structures of bis (nitrato)- bis ( N -2-hydroxyethyl- pyridine-2-carboxamidine- N,N ′)copper(II) and bromo-bis( N -3-hydroxy-propylpyridine-2-carboxamidine- N,N ′)copper(II) bromide

Abstract

Condensation of pyridine-2-carbonitrile (2-CNpy) with 2-aminoethanol (L1) or 1-amino-3-propanol (L2) in alcohol solutions of CuX2 (X = , , Cl− and Br−) proceeds readily under mild conditions to form stable solid complexes [Cu(NO3)2(amL1-NH)2], [Cu(amL1-NH)2](ClO4)2, [Cu(amL2-NH)2](ClO4)2, [CuCl2(amL2-NH2)] · H2O, [CuCl2(amL2-NH)2] and [CuBr(amL2-NH)2]Br, which contain the imino form of N-2-hydroxyethylpyridine-2-carboxamidine (amL1-NH) and imino or amino forms of N-3-hydroxypropylpyridine-2-carboxamidine (amL2-NH or amL2-NH2). Crystal structures of [Cu(NO3)2(N-2-hydroxyethyl-pyridine-2-carboxamidine-N,N′)2] and [CuBr(N-3-hydroxypropylpyridine-2-carboxamidine-N,N′)2]Br and IR data confirm bidentate N,N-coordination of N-hydroxyalkylpyridine-2-carboxamidines (via the nitrogen atom of the pyridine ring as well as the nitrogen atom of the terminal imino group). The structure of [Cu(NO3)2(amL1-NH)2] consists of well-separated centrosymmetrical Cu(amL1-NH)2(NO3)2 entities, including two independent kinds of molecules (molecule [Cu(NO3)2(amL1-NH)2] and molecule [Cu(amL1-NH)2](NO3)2) with central atoms Cu1 and Cu2 located at two crystallographically independent symmetry centres. [CuCl2(amL2-NH2)] · H2O contains only a terdentate N,N,O-coordinated amino form of N-3-hydroxypropylpyridine-2-carbox-amidine (amL2-NH2). The analogous reaction of 2-CNpy with L2 and M(NCS)2 (M = Ni and Co) in ethanol leads to the solid complexes [Co(NCS)2(oxaL2)2] · 2H2O and [Ni(NCS)2(oxaL2)2], which contain 2-pyridinyl-1,3-oxazine (oxaL2). Based on the molecular structure, electronic and IR spectroscopic data are discussed.