Structural diversity among some dialkyltin(IV) benzoate and related derivatives

Abstract

The mol­ecular structures of five diorganotin(IV) carboxyl­ates, (I)–(V), can be categorized into two main well-known structural types for such Sn com­plexes. One is the mononuclear dialkytin(IV) carboxyl­ates with an [R2Sn(LH)2]-type skew-trapezoidal bipyramid, where the alkyl ligands are in pseudo-axial positions and the O atoms from two asymmetrically coordinated bidentate carboxyl­ate ligands are in the equatorial plane. This structure type is adopted by di­butyl­bis­{(E)-2-hy­droxy-5-[(3-methyl­phen­yl)diazen­yl]benzoato}tin(IV) cyclo­hexane hemisolvate, [Sn(C4H9)2(C14H11N2O3)2]·0.5C6H12, (I), di­benzyl­bis­{(E)-5-[(4-bromo­phen­yl)diazen­yl]-2-hy­droxy­benzoato}tin(IV), [Sn(C7H7)2(C13H8BrN2O3)2], (II), and aqua­dibenzyl­bis­(4-{(E)-[(Z)-4-hy­droxy­pent-3-en-2-yl­idene]amino}­benzoato)tin(IV) benzene disolvate, [Sn(C7H7)2(C12H12NO3)2(H2O)]·2C6H6, (III), although the latter has an additional water ligand to give a distorted penta­gonal bipyramidal coordination geometry in which the carboxyl­ate groups are more symmetrically coordinated to the Sn atom than in (I) and (II). The other structure motif is that of the tetra­nuclear bis­(di­carboxyl­ato­tetra­organodistannoxanes), {[R2Sn(LH)]2O}2, which contain an Sn4O2 core decorated with four bridging carboxyl­ate ligands, plus two alkyl ligands at each SnIV centre. The complexes octa­butyl­tetra­kis­{μ-(E)-4-[(4-hy­droxy-3,5-di­methyl­phen­yl)diazen­yl]benzoato}di-μ3-oxido-tetra­tin(IV) ethanol disolvate, [Sn4(C4H9)8(C15H13N2O3)4O2]·2C2H6O, (IV), and octa­butyl­tetra­kis­{(E)-3-[(2-hy­droxy­benzyl­idene)amino]­propano­ato}di-μ3-oxido-tetra­tin(IV), [Sn4(C4H9)8(C10H10NO3)4O2], (V), display this motif. The structures obtained correlate with the 1:1 and 1:2 stoichiometric ratios of the di­alkyl­tin(IV) and carb­oxy­lic acid starting materials in the syntheses. The supra­molecular structures arising from consideration of secondary Sn...O inter­actions and/or classic hydrogen bonds include discrete mol­ecules for (V), centrosymmetric dimers for (I), extended chains for (II) and (III), and sheets for (IV).