Models for Platinum−Rhenium Bimetallic Catalysts:  Sulfidation of Pt₃Re Clusters

Abstract

Sulfidation of platinum-rhenium cluster complexes has been studied as a model for sulfidation of bimetallic Pt−Re/Al2O3 catalysts used in petroleum re-forming. Sulfidation of [Pt3{Re(CO)3}(μ-dppm)3][PF6] (1[PF6]; dppm = Ph2PCH2PPh2) using propylene sulfide as reagent gives the clusters [Pt3{Re(CO)3S}(μ-dppm)3][PF6], (2[PF6]) and then [Pt3{Re(CO)3}(μ3-S)2(μ-dppm)3][PF6] (3[PF6]). Similar sulfidation of the oxo clusters [Pt3{Re(CO)3}(μ3-O)(μ-dppm)3][PF6], [Pt3{Re(CO)3}(μ3-O)2(μ-dppm)3][PF6], and [Pt3(ReO3)(μ-dppm)3][PF6] gives the oxo−sulfido clusters [Pt3{Re(CO)3}(μ3-O)(μ3-S)(μ-dppm)3][PF6] (4[PF6]), [Pt3{Re(CO)3}(μ3-O)2(μ3-S)(μ-dppm)3][PF6] (5[PF6]), and [Pt3(ReO3)(μ3-S)2(μ-dppm)3][PF6] (6[PF6]), respectively. Oxidation of the sulfido clusters 2 and 3 by Me3NO or H2O2 gave the oxo-sulfido clusters [Pt3{Re(CO)3S}(μ3-O)(μ-dppm)3][PF6](7[PF6]) and [Pt3{Re(CO)3}(μ3-O)(μ3-S)2(μ-dppm)3][PF6] (8[PF6]), respectively. The clusters 3−5 have been characterized crystallographically; addition of each μ3-O or μ3-S group leads to a decrease in metal−metal bonding in the cluster complexes.

Regio- and Stereoselective Insertion Reactions of Thiiranes into Pt−Mn (or Re) Bond in Organoplatinum−Manganese or −Rhenium Heterodinuclear Complexes as Intermediates toward Desulfurization Reaction

“…Introduction of direct heterotransition-metal direct bonds in cluster complexes is expected to create a new era of transition-metal chemistry in relation to multimetallic catalysis, and thus many investigations on heterotransition-metal complexes have been reported in recent years . Bimetallic catalysis such as sulfurized Pt−Re oil reforming catalysts and Co−Mo and Ni−Mo hydrodesulfurization (HDS) catalysts shows cooperative effects of these metals, but the origin of such effect is far from understood at the molecular level. Although extensive research has been devoted to elucidate the mechanisms of the reactions of heterodinuclear transition-metal complexes and clusters with thiiranes and benzothiophenes, few examples of direct participation of both metal centers have been found in the literature .…”

Ethylene Oxide and Propylene Sulfide Complexes of Silver(I): Synthesis and Characterization of [HB(3,5-(CF3)2Pz)3]Ag(OC2H4) and [HB(3,5-(CF3)2Pz)3]Ag(SC3H6)

“…Propylene sulfide is used as a monomer in various metal-catalyzed polymerization processes. ,− It is also a good sulfur atom donor to metal ions. − However, structurally characterized metal−propylene sulfide species (or any other thiiranes) are rare. ,− To our knowledge, the complex presented herein represents the only structurally characterized example containing silver−thiirane bonding.…”

“…29,[35][36][37][38][39][40] It is also a good sulfur atom donor to metal ions. [41][42][43][44][45][46][47][48] However, structurally characterized metal-propylene sulfide species (or any other thiiranes) are rare. 34,[49][50][51][52] To our knowledge, the complex presented herein represents the only structurally characterized example containing silver-thiirane bonding.…”

[Me8Pt4ReS4]− and related PtMe2-containing clusters derived from tetrathiorhenate

“…Several Pt 3 Re species have been characterized previously by Puddephatt. These workers employed Pt 3 (PR 3 ) 6 platform to which was attached Re(CO) 3 + [11,12]. Pt-Re-S species are compositionally related to catalysts widely used in petroleum reforming [13].…”