Synthesis and structural characterization of new ladder-like organostannoxanes derived from carboxylic acid derivatives: [C5H4N(p-CO2)]2[Bu2Sn]4(μ3-O)2(μ2-OH)2, [Ph2CHCO2]4[Bu2Sn]4(μ3-O)2, and [(p-NH2)-C6H4-CO2]2[Bu2Sn]4(μ3-O)2(μ2-OH)2

Abstract

Three types of ladder-like organostannoxanes, [C5H4N(p-CO2)]2[Bu2Sn]4(μ3-O)2(μ2-OH)2 (1), [Ph2CHCO2]4[Bu2Sn]4(μ3-O)2 (2), and [(p-NH2)-C6H4-CO2]2[Bu2Sn]4(μ3-O)2(μ2-OH)2 (3), have been synthesized and characterized using elemental analyses, Fourier-transform infrared spectroscopy, nuclear magnetic resonance (1H, 13C) experiments, and, for 1 and 2, single-crystal X-ray diffraction analysis. X-Ray diffraction discloses that complexes adopt tetranuclear tin(iv) ladder-like structures containing two (1) or four (2) deprotonated ligands. The essential difference between their molecular structures is that in 2 there are four carboxylate ligands, while in 1 and 3 there are two. The crystal structure of 1 reveals them to be a tetranuclear structure containing a three-rung-staircase Sn4O4 core. The Sn4O4 cluster consists of a ladder of four Sn2O2 units. For 2, the structure is a tetranuclear centrosymmetric dimer of an oxoditin unit having a central four-member ring. In this complex, the central Sn2O2 core is fused with two four-member and two six-member rings. In the structures, there are two types of tin ions arranged in distorted trigonal bipyramid geometry or octahedron geometry. A series of O–H⋯N, C–H⋯O, and C–H⋯π intermolecular hydrogen bonds in these complexes play an important function in the supramolecular, or two-dimensional network structures are formed by these interactions.

Keywords

• diphenylacetate¸ pyridine-4-carboxylate
• 4-aminobenzenecarboxylate
• ladder and organostannoxanes