Photochemical substitution reactions of some transition metal carbonyl complexes

Transition metal carbonyl complexes especially VIB metal carbonyls are the oldest classes of organometallic chemistry. These are among the most well studied organometallic compounds. Metal carbonyls have been proved as reactive species in homogeneous catalytic reactions such as hydrogenation, hydroformylation and carbonylation. Carbon monoxide serves simply as a ligand providing the complex with the necessary reactivity and/or stability to allow reaction to ensue. A large number of Schiff bases and their complexes have been studied for their interesting and important properties, such as their ability to reversibly bind oxygen, catalytic activity in the hydrogenation of olefins and complexing ability towards some toxic metals.We have investigated photochemical reactions of VIB metal carbonyl complexes with salen type [O, N, N, O] Schiff bases in THF. The new 1-6 complexes have been synthesized and characterized by elemental analyses, FTIR, 1H-NMR and mass spectra. The spectroscopic studies show that first ligand is coordinated to the central metal as a tetradentate ligand coordinating via the central azomethine nitrogens (C=N) and phenolic oxygen atoms to the central metal in 1-3, whereas second ligand is coordinated to the central metal as a tetradentate ligand coordinating via aromatic methoxy and phenolic oxygen atoms to the central metal in 4-6.