Palladium(II) and platinum(II) complexes of β-functionalized ethyl selenolates: Effect of substitution on synthesis, reactivity, spectroscopy, structures and thermal behavior

Abstract

Sodium ethylselenolates with functional groups X (where X = –OH, –COOH, –COOMe and –COOEt) at β-carbon were prepared in situ by reductive cleavage of corresponding diselenide with NaBH 4 either in methanol or aqueous ammonia. Treatment of these selenolates with [M 2Cl 2(μ–Cl) 2( PR 3 ′ ) 2] (M = Pd or Pt; PR 3 ′ = PMePh 2, P nPr 3) in different stoichiometry yielded various bi- and tri-nuclear complexes. The homoleptic hexanuclear complexes [Pd(μ–SeCH 2CH 2X) 2] 6 (X = OH, COOH, COOEt), were obtained by reacting Na 2PdCl 4 with NaSeCH 2CH 2X. All these complexes have been fully characterized. Molecular structures of ethylselenolates containing hydroxyl and carboxylic acid groups revealed solid state associated structures through inter-molecular hydrogen bond interactions. Trinuclear complex, [Pd 3Cl 2(μ–SeCH 2CH 2COOH) 4(P nPr 3) 2] ( 3a), was disposed in a boat form unlike chair conformation observed for the corresponding methylester complex. The effect of β-functionality in ethylselenolate ligands towards reactivity, structures and thermal properties of palladium and platinum complexes has been extensively studied.