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

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 NaBH4 either in methanol or aqueous ammonia. Treatment of these selenolates with [M2Cl2(μ–Cl)2(View the MathML sourcePR3′)2] (M = Pd or Pt; View the MathML sourcePR3′ = PMePh2, PnPr3) in different stoichiometry yielded various bi- and tri-nuclear complexes. The homoleptic hexanuclear complexes [Pd(μ–SeCH2CH2X)2]6 (X = OH, COOH, COOEt), were obtained by reacting Na2PdCl4 with NaSeCH2CH2X. 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, [Pd3Cl2(μ–SeCH2CH2COOH)4(PnPr3)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.