Title: Solid state and solution structural investigation of homoleptic tin(IV) alkoxide compounds. Part I. Sn(O—<i>t</i>-Bu)<sub>4</sub> and [Sn(O—<i>i</i>-Pr)<sub>4</sub>•HO—<i>i</i>-Pr]<sub>2</sub>
Abstract:The crystal and molecular structures of Sn(O—t-Bu) 4 • and [Sn(O—i-Pr) 4 •HO—i-Pr] 2 have been determined by single-crystal X-ray diffraction. Sn(O—t-Bu) 4 crystallizes in the monoclinic crystal syste...The crystal and molecular structures of Sn(O—t-Bu) 4 • and [Sn(O—i-Pr) 4 •HO—i-Pr] 2 have been determined by single-crystal X-ray diffraction. Sn(O—t-Bu) 4 crystallizes in the monoclinic crystal system with space group C2/c, where a = 17.382(6) Å, b = 8.742(2) Å, c = 15.518(5) Å, β = 116.44(1)°, Z = 4, and R = 2.5%. Sn(O—t-Bu) 4 is monomeric in the solid state, with a distorted tetrahedral tin coordination environment. [Sn(O—i-Pr) 4 •HO—i-Pr] 2 crystallizes in the monoclinic crystal system with space group P2 1 /n, where a = 11.808(3) Å, b = 14.356(3) Å, c = 12.380(2) Å, β = 95.27(2)°, Z = 2, and R = 4.9%. [Sn(O—i-Pr) 4 •HO—i-Pr] 2 exhibits an edge-shared, bi-octahedral structure in the solid state that is distorted due to the presence of asymmetric hydrogen bonding between axially coordinated alcohol ligands and an isopropoxide ligand. 13 C NMR and IR spectroscopic data have been recorded for Sn(O—t-Bu) 4 and Sn(O—t-Bu-d 9 ) 4 to establish criteria for unambiguous identification of solution structures of tin(IV) alkoxides. It is demonstrated that the two-bond [Formula: see text] coupling constant is larger for terminal alkoxide ligands than for μ 2 -alkoxide bridges, and the ν(Sn—O) stretching frequency has been assigned. The dynamic solution behaviour of [Sn(O—i-Pr) 4 •HO—i-Pr] 2 has been studied using variable temperature 1 H and 13 C NMR spectroscopy. The data obtained are consistent with a process that involves rapid reversible dissociation of isopropanol at room temperature. Upon cooling, the equilibrium concentration of the species with coordinated alcohol increases, and the molecule undergoes rapid intramolecular proton transfer (AG ≠ < 11.9 kcalmol −1 ). Upon further cooling, the 13 C NMR data are consistent with a solution structure analogous to that found in the solid state. Key words: tin, alkoxide, NMR, dynamic, structure.Read More
Publication Year: 1991
Publication Date: 1991-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 87
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