Synthesis and Characterization of Stable Hetereocyclic (Schiff Base) Divalent Tin Species and Photogeneration of Their Transition Metal Carbonyl Complexes

Abstract

New stable divalent heterocyclic species [SnL1; 1, SnL2; 2] using ONNO and SNNS tetradentate Schiff bases; N,N′-bis(salicylidene)-1,2-bis(o-aminophenoxy)ethane (H2L1) and N,N′-bis(2-aminothiophenol)-1,4-bis(2-carboxaldehydephenoxy)butane (H2L2) were obtained in good yields by alcolysis of the M-N bonds of the divalent precursor Sn[N(SiMe3)2]2 by diols. They have been isolated as solids at ambient temperature and are monomeric. FT-IR, 1H and 119Sn-NMR spectra are suggestive of N … M intramolecular coordination. Then the synthesis and characterization of the new stable mono and cis-disubstituted Sn(II) chromium and tungsten carbonyl complexes [L1Sn]M(CO)5 (M= Cr, 3; W, 4); [L2Sn]M(CO)5 (M= Cr, 5; W, 6); cis-[L1Sn]2M(CO)4 (M= Cr, 7; W, 8) and cis-[L2Sn]2M(CO)4 (M= Cr, 9; W, 10) are described. Pentacarbonyl complexes (3–6) were obtained in high yields by treatment of the M(CO)5THF (M= Cr, W) intermediates with the divalent species [SnL1; 1, SnL2; 2] and tetracarbonyl complexes (7–10) were synthesized by the photochemical reactions of [LnSn]M(CO)5 with [LnSn] (n = 1, 2). Each of the new carbonyl complexes has been characterized by IR, 1H, 13C, 119Sn-NMR spectroscopy, and mass spectrometry. The sigma donor and pi acceptor ability of the divalent tin species [SnL1, 1; SnL2, 2] as ligands in the transition metal carbonyl complexes (3–10) is discussed by comparing ν(CO) stretching frequencies.