Studies on a new dinuclear CoII–pterin complex exhibiting reactivity towards phenylalanine and bromobenzene

Abstract

2-Pivaloylamino-6-acetonyl-isoxanthopterin (1, H 2 L) has been reacted with CoCl 2 Á 6H 2 O under suitable conditions for synthesizing the new compound Na½Co II 2 (L)Cl 3 ðCH 3 OHÞ 3 ] (2). It has been characterized by elemental analysis, electrospray ionization mass spectrometry, magnetic susceptibility measurement, different spectroscopic techniques, and cyclic voltammetry. Molecular mechanics (MM2) method provided with its optimized geometry (having lowest steric energy), consistent with the above data; the optimized bond lengths and bond angles data tally with the literature X-ray structural data. Reactivity of (2) towards phenylalanine in the presence of O 2 in methanol has been followed both kinetically and stoichiometrically; a reasonable amount of tyrosine could be recovered from the reaction medium. The negative DS # value ()274.0 J mol )1 deg À1 Þ indicates an associative pathway for this process. (2) is also able to react with bromobenzene as indicated by time-dependent absorption spectra as well as product identification. Efficacy of the pterin ligand residue ðL 2À Þ of (2) in rendering the latter reactive towards the above-mentioned organic compounds, has been discussed on the basis of experimental evidence.