Guilty on Two Counts: Stepwise Coordination of Two Fluoride Anions to the Antimony Atom of a Noninnocent Stibine Ligand

Abstract

In our efforts to investigate the coordination noninnocent behavior of transition-metal stibine complexes, we have prepared a series of platinum complexes bearing the tetradentate ligand (o-(Ph2P)C6H4)3Sb (L). Treatment of (Et2S)2PtCl2 with L affords the lantern complex (o-(Ph2P)C6H4)3SbCl)Pt(Cl) (1-Cl), which undergoes facile exchange with fluoride to form the fluorostiboranyl complex ((o-(Ph2P)C6H4)3SbF)Pt(Cl) (1-F). Starting from 1-Cl, anion exchange and abstraction reactions afford [((o-(Ph2P)C6H4)3Sb)Pt(CyNC)][SbF6]2, ([2][SbF6]2), [((o-(Ph2P)C6H4)3SbF)Pt(CyNC)][SbF6] ([3][SbF6]), and ((o-(Ph2P)C6H4)3SbF2)Pt(CyNC) (4), which are related by the formal stepwise coordination of two fluoride ligands to the antimony center. Structural studies of this series show that the Sb–Pt bond lengthens upon sequential fluoride coordination at the antimony center, consistent with the weakening of the Sb–Pt interaction. Natural bond orbital (NBO) calculations performed at the density functional theory (DFT) optimized ...