Properties and structures of five-coordinated cobalt(II) and copper(II) complexes of N,N′-bis[(5-chloro-2-hydroxyphenyl)phenylmethylene]-4-oxaheptane-1,7- diamine

Article abstract of DOI:10.1021/ic50218a050

The title complexes, [Co(cbpO)] and (Cu(cbpO)], have been synthesized and studied by single-crystal X-ray diffraction. The copper complex contains the metal atom in a distorted square pyramid whose apex is formed by the Cu-O bond to the ether oxygen atom. The O₂N₂ base of the square pyramid is distorted so as to give some trigonal-bipyramidal character to the geometry, the N atoms being raised above (0.35 ?) the base and the Cu atom and the O atoms below it (0.06 and 0.35 ?, respectively). The Cu-O bond to the ether oxygen is markedly elongated (2.575 ?), indicating a rather weak linkage. This compares with apical bond elongations of 2.374 (10) and 2.686 (1) ?, respectively, in the related five-coordinated [Cu(mbpN)] and [Cu(cbpS)]. If the long Cu-O bond were absent, the copper environment would approximate a flattened tetrahedron. The metal environment in [Co(cbpO)] is distorted trigonal bipyramidal with the two Co-N bonds axial and the three Co-O bonds equatorial. The Co-O bond to the ether oxygen is relatively strong (2.124 (3) ?) in contrast with the [Cu(cbpO)] analogue. The observation of metal to ether oxygen bonding at all in these complexes contrasts with the apparent absence of such bonds in a series of related salicylaldimine complexes. (Co(cbpO)] readily forms a six-coordinated pyridine adduct, while [Cu(cbpO)] appears not to do so, even in pyridine solution. Crystal data for [Cu(cbpO)]: space group C2/c, Z = 8, a = 13.993 (5) ?, b = 13.652 (8) ?, c = 29.40 (1) ?, β = 91.46 (3)°, V = 5615 ?³, R = 5.8% for 1840 reflections. Crystal data for [Co(cbpO)]: space group C2/c, Z = 8, a = 13.914 (7) ?, b = 13.477 (4) ?, c = 29.86 (1) ?, β = 90.57 (3)°, V = 5599 ?³, R = 6.1% for 3397 reflections.