Crown and Extended Organooxotin Compounds Formed with Phosphinate Ligands. A New Class of Tetranuclear Tin Clusters

Abstract

A new class of organooxotin compounds was discovered by the synthesis of the tetranuclear clusters [(n- BuSn)2OH(O2PPh2)3(OSPPh2)2]2.8C6H6(1), [(n-BuSn(O)O2P(t-Bu)2)(n-BuSn)(OH)2O2P(t-Bu)2)]2[H] [O2P(t-Bu)2] (2), and [(MeSn(O)O2P(t-Bu)2)(MeSn(OH)(OMe)O2P(t-Bu)2)]2[H] [O2P(t-Bu)2].4MeOH.2H2O (3). The former compound 1 has an extended structural array while 2 and 3 have crown structures. All contain hexacoordinated tin atoms with bridging phosphinate ligands and distannoxane linkages. They are synthesized for the most part by reaction schemes employing stannoic and phosphinic acids. 119Sn and 31P NMR characterize their solution-state structures, consistent with their X-ray structures. NMR spectra also show the appearance of a variety of other cluster derivatives arising during synthesis. The Sn-O skeletal arrangement of the crown observed for 2 and 3 is isomeric to the skeletal form of the adamantane structure, the latter of which is present, for example, in (MeSn)4S6. The occurrence of 1–3 suggests the possibility of other oligomeric geometries based on common structural features. 1 crystallizes in the monoclinic space group P21/n with a = 17.708 (7) Å, b = 25.884 (10) Å, c = 20.803 (5) Å, β = 110.30 (3)°, and Z = 2. 2 crystallizes in the monoclinic space group P21/n with a = 12.658 (4) Å, b = 24.129 (12) Å, c = 26.235 (5) Å, β = 98.03 (2)°, and Z = 4. 3 crystallizes in the orthorhombic space group Pbcn with a = 20.273 (3) Å, b = 16.395 (2) Å, c = 24.320 (4) Å, and Z = 4. The final conventional unweighted residuals are 0.057 (1), 0.056 (2), and 0.054 (3). © 1988, American Chemical Society. All rights reserved.