Structure and Bonding in a Diamond‐Shaped Tin Cluster Possessing a <i>cyclo</i>‐Sn₄ Core

Abstract A tetrameric cluster composed entirely of (aryl)Sn units, [DMPSn] 4 (DMP=2,6‐dimesitylphenyl), has been prepared by reduction of [DMPSnCl] 2 with a variety of reductants. This cluster was characterized in solution by multinuclear NMR spectroscopies, as well as in the solid‐state by single crystal X‐ray diffraction analysis. This species is stereochemically nonrigid in solution and possesses a cyclo ‐Sn 4 core whose DMP substituents are equivalent at higher temperatures. The solid‐state molecular structure is remarkably unsymmetrical and possesses a nearly planar cyclo ‐Sn 4 core. The DMP substituents are arranged such that three are approximately coplanar, while one is nearly perpendicular to the cyclo ‐Sn 4 core. Density functional theory calculations for a [PhSn] 4 model system show that this distorted geometry about the cyclo ‐Sn 4 core maximizes σ‐bonding between the Sn centers in a manner reminiscent of trans ‐bent bonding in the heavy group 14 analogues of alkenes and alkynes.