Stable Olefin Complexes of Pt(II) Containing Trichlorostannate(II) Ligands: Structure of [Ph₄As][Pt(SnCl₃)₃(1,5‐cod)]

Abstract

tahedral array of six 0-atoms. The iron ions are coupled together by twelve p2-hydroxo bridges and by two p3-oxo bridges (Fig. 1). The cyclic amine ligands form a hydrophobic "surface" of the complex cation (Fig. 2). There are five relatively short Fe . . . Fe distances (= 305 pm), which arise from edge-to-edge coupling of octahedra via 0x0-or hydroxo-bridges, and eight longer ones (= 345 pm). The cation has idealized C,-symmetry.

The First Alkene−Platinum−Silyl Complexes: Lifting the Hydrosilation Mechanism Shroud with Long-Lived Precatalytic Intermediates and True Pt Catalysts

“…Because the salient NMR chemical shifts for all the complexes 1 follow an identical pattern, the structural aspects of these complexes are also expected to be identical. Additionally, perhaps the strongest indirect support for the structural features of 1 is evident in a report by Pregosin and co-workers, where the preparation (via different chemistry) of a series of anionic Pt complexes containing various mono-olefin, chloride, and stannyl groups on Pt is described . These anionic stannyl−Pt−alkene complexes are direct equivalents of Zeise's salt and can also be visualized as anionic monomeric analogues of 1 .…”

“…An important question that arises with respect to the ability of compounds 2 to behave as true hydrosilation catalysts is whether these complexes with two silyl groups on Pt are capable of accommodating a third silyl group on Pt via oxidative addition of SiH to 2 . Indirect but very strong evidence for this ability is provided by the known anionic complexes of Pt containing η 4 -bound COD and three trichlorostannyl groups, such as [Ph 4 As] + [(COD)Pt(SnCl 3 ) 3 ] - . If platinum can accommodate three stannyl groups and an η 4 -bound COD, then the simultaneous bonding of three silyl groups (smaller than equivalent stannyl groups) and an η 4 -coordinated COD on platinum can be readily visualized.…”

“…Additionally, perhaps the strongest indirect support for the structural features of 1 is evident in a report by Pregosin and co-workers, where the preparation (via different chemistry) of a series of anionic Pt complexes containing various mono-olefin, chloride, and stannyl groups on Pt is described. 28 These anionic stannyl-Pt-alkene complexes are direct equivalents of Zeise's salt and can also be visualized as anionic monomeric analogues of 1. Indeed, one might anticipate that such anionic and monomeric complexes can be made from 1 via appropriate transformations or directly from Na 2 PtCl 4 .…”

“…Indirect but very strong evidence for this ability is provided by the known anionic complexes of Pt containing η 4 -bound COD and three trichlorostannyl groups, such as [Ph 4 As] + [(COD)-Pt(SnCl 3 ) 3 ] -. 28 If platinum can accommodate three stannyl groups and an η 4 -bound COD, then the simultaneous bonding of three silyl groups (smaller than equivalent stannyl groups) and an η 4 -coordinated COD on platinum can be readily visualized. Thus, a much clearer catalytic cycle for hydrosilation with chloride-based Pt(2+) precatalysts containing COD or another non-hydrosilatable ligand may now be proposed (Schemes 4 and 5).…”