Synthesis, molecular structure, and characterization in solution of a new series of inorganic and organometallic Co(III) Schiff base complexes

A new series of inorganic and organometallic cobalt Schiff base complexes containing the tetradentate ligand tmsalen (4,4',7,7', tetramethylsalen) have been synthesized. They have been characterized by H-1 NMR and UV-Vis spectroscopy and by ESI MS spectrometry, both in coordinating and non-coordinating solvents. Two inorganic complexes [Co(tmsalen)(L)(2)]ClO4, where L = py (2) and N-Melm (3), two dimeric organometallic derivatives [RCo(tmsalen)](2) (R = CH3 (4) and CH2CF3 (7)) and one organometallic penta-coordinated species (R = i-Pr (6)) have been structurally characterized. It is noteworthy that the formation of organometallic dimeric and penta-coordinated species occurs even if the synthesis is carried out in presence of py. Solution data confirm the strong tendency to the penta-coordination of the complexes containing the most electron-donating alkyl groups, which maintain penta-coordination even in methanol. (C) 2003 Elsevier Science B.V. All rights reserved.