Coordination Isomers of Trinuclear Pt₂Hg Complex That Differ in Type of Metal–Metal Bond

Abstract

New type isomers that differ in metal–metal bond type are isolated. One is the Pt–Hg–Pt complex, which has two metal–metal covalent bonds, Pt–Hg = 2.5459(8) and 2.5483(7) Å, and the other is the Pt→Hg–Pt complex, which has one metal–metal covalent bond, Pt–Hg = 2.5744(6) Å, and one metal–metal dative bond, Pt→Hg = 2.6635(7) Å.

Reactions of Cycloplatinated Guanidine Complexes with Hg(OC(O)CF3)2: Formation of a One-Dimensional Coordination Polymer Containing a Pt2Hg(μ2-S(O)Me2-S,O) Repeating Unit versus a Discrete Pt2Hg2 Complex

“…The values of δ( 195 Pt) reported by Vicente, Yamaguchi, and co-workers for Pt 2 Hg complexes which are in "two covalent form" are given in Table 1. 15,22 The δ( 195 Pt) ranges observed for the three species of 3 in both of the solvents compare favorably well with the shift ranges reported by Yamaguchi and co-workers for their Pt 2 Hg complexes.…”

“…Yamaguchi and co-workers suggest a δ( 195 Pt) difference of greater than 1000 ppm for Pt(II) and Pt(III) species. 15 Thus, we believe, in the absence of any basic site in C 6 D 6 medium, the bonding within the Pt 2 Hg unit changes from "two-covalent-type" (Pt−Hg−Pt) in the solid state (3) to "two-coordinate-type" (Pt→Hg←Pt) in solution (C 6 D 6 ) as illustrated in 6−8. However, "twocovalent-type" (Pt−Hg−Pt) bonding within the Pt 2 Hg unit It is well-known that in cycloplatinated Hg(II) complexes wherein the two metal atoms are bridged by carboxylato, triazenato, and formamidinato ligands and when the Pt atom is six-coordinate, a covalent Pt−Hg bond is adopted, and when the Pt atom is five-coordinate, a dative Pt→ Hg bond is adopted.…”

“…The reactions of organoplatinum complexes with HgX 2 (X = Cl, Br, I, OC­(O)­R; R = Me, CF 3 ) have been extensively studied with a view aimed at understanding the mechanism of the reactions such as redox reactions and transmetalation, the nature of the products, and bonding between the Pt and the Hg atoms in the resulting products. − A variety of complexes have been isolated from the aforementioned reactions, and representative complexes have been structurally characterized. The generic formulas of various types of complexes obtained from the aforementioned reactions are grouped in Scheme .…”

“…17 Complex B can decompose to afford either dimeric organoplatinum(III) complexes C and D depending upon X and the Pt:Hg molar ratio or the monomeric organoplatinum-(IV) complex E. The formation of Hg 0 was observed during the oxidation of Pt(II) to afford C or E. 8,17 Alternatively, complex B can reductively eliminate Hg in the form of RHgX to afford complex F. 11,23 Complex B upon reaction with an organoplatinum(II) reagent can give either the "dativecovalent-type"complex G or "two-covalent-type" complex H when the Hg atom in B is sufficiently electrophilic or when the Pt(II) atom in organoplatinum(II) reagent is sufficiently nucleophilic. 10,12,13,15,22 Puddephatt and co-workers have structurally characterized a pair of complexes of type G, namely [PtMe 2 X(HgX)( t bu 2 bpy){PtMe 2 ( t bu 2 bpy)}] (X = Br, OC(O)CF 3 ). 12 Subsequently, Yamaguchi and co-workers have shown that the aforementioned bromo derivative in CDCl 3 at −60 °C exists in the form of H rather than G. 15 Thus, even subtle factors such as crystal packing forces influence the bonding in the Pt 2 Hg unit present in forms G and H.…”

“…10,12,13,15,22 Puddephatt and co-workers have structurally characterized a pair of complexes of type G, namely [PtMe 2 X(HgX)( t bu 2 bpy){PtMe 2 ( t bu 2 bpy)}] (X = Br, OC(O)CF 3 ). 12 Subsequently, Yamaguchi and co-workers have shown that the aforementioned bromo derivative in CDCl 3 at −60 °C exists in the form of H rather than G. 15 Thus, even subtle factors such as crystal packing forces influence the bonding in the Pt 2 Hg unit present in forms G and H.…”