Unusual structurally characterized pyridine carbinoxide copper(II) coordination compounds, isolated from organic solvents

The coordination behavior of pyridine carbinoxide [NC5H4(CH2O)-2 or OPy] with copper in organic solvents was crystallographically determined. Initial attempts to generate the Cu(II) OPy derivatives from an alcoholysis exchange of Cu(OCH3)(2), with H-OPy in toluene, led to the isolation of [Cu(mu(c)-OPy)((OPy)-Py-c)](2) (1, "c'' indicates chelation). The square-based pyramidal geometries noted for each Cu center resulted from one (OPy)-Py-c and two mu(c)-OPy ligands, generating an unusual C-1 symmetry. From the reaction of H-OPy and the Cu(I) species Cu(C6H2(CH3)(3)-2,4,6), mononuclear Cu(II) complex Cu((OPy)-Py-c)(2)(H-OPy)(2) (2) was isolated. Compound 2 is unusual in that it adopts a square planar arrangement around the Cu metal center using two (OPy)-Py-c ligands; however, the metal center also coordinates with two H-OPy molecules forming an octahedral geometry. Upon dissolution in water, both 1 and 2 react to form the previously reported Cu((OPy)-Py-c)(2)center dot 2H(2)O (3). Attempts to add a Lewis base through dissolution of 1 in selected solvents (i.e., tetrahydrofuran, pyridine, 1-methylimidazole) led to [Cu(mu(c)-OPy)((OPy)-Py-c)](2)center dot H2O (4), which possesses a C-2 symmetry. The water was believed to be extracted from the "dry'' solvents. A Cl derivative was also solved for the Cu(II)/Cu(I) species [Cu(OPy)(2)](2)[CuCl(H-OPy)(2)](2) (5) from tetrahydrofuran dried over apparently contaminated sieves.