Experimental and computational preference for phosphine regioselectivity and stereoselective tripodal rotation in HOs₃(CO)₈(PPh₃)₂(μ-1,2-N,C-η¹,κ¹-C₇H₄NS)

Abstract

The site preference for PPh3 substitution in HOs3(CO)10(PPh3)2(μ-1,2-N,C-η1,κ1-C7H4NS) (1) has been investigated.

Reaction of electron-deficient 6-methoxyquinolinate-substituted cluster [Os3(CO)9{μ3-η1,κ1-C9H5N(6-OMe)}(μ-H)] with PPh3: Thermally induced ligand isomerization, decarbonylation and orthometallation

“…The PPh3 ligand occupies an equatorial site at the Os(1) center cis to the hydride that also serves as the coordination site for the metallated carbon atom, C(10), on the 6-methoxyquinolinate ligand. The gross structural features of 2 are virtually identical to those reported for the related triosmium clusters [Os3(CO)9(PPh3)(µ-η 1 ,κ 1 -C7H3NSR)(µ-H)] (R = H, Me) [27], [Os3(CO)9(PPh3)(µ-…”

“…As part of our studies on the reactivity of electron-deficient [Os3(CO)9(μ3-η 1 ,κ 1 -L)(μ-H)] with two electron donor ligands, we recently reported the reactions of benzothiazolate triosmium clusters [Os3(CO)9(µ3-η 1 ,κ 1 -C7H3NSR)(µ-H)] (R = H, Me) with PPh3 that led to the isolation of electron-precise adducts [Os3(CO)9(PPh3)(µ, 2 -C7H3NSR)(µ-H)] in which PPh3 ligand occupies an equatorial site at the carbon bound osmium. Thermolysis of these adducts afforded a number of products resulting from isomerization, decarbonylation and orthometallation of the ancillary PPh3 ligand [27]. As a continuation of our previous studies,…”

Activation of thiosaccharin at a polynuclear osmium cluster

“…The asymmetric unit of 2 also contains two independent molecules that do not show any significant structural differences, allowing us to limit our discussion to the structure that is depicted 1) 117.7(4o ] provide space for the hydride to bridge the Os(1)-Os(2) edge in a manner similar to the hydride ligand in the corresponding saccharinate analog [HOs3(CO)10(μ-N,O-1,2-sac)] [19]. The location of the hydride at the heterocyclic bridged Os-Os bond receives additional support from the comprehensive report recently published by us where the energies of hydride isomers at related heterocyclic-bridged triosmium clusters were examined by DFT [38].…”

“…Of the numerous hydride isomers computationally analyzed in the latter study, the thermodynamic locus for hydride was found to coincide with the Os-Os bond that was also bridged by the ancillary heterocycle [38]. The DFT-optimized structure of E is displayed alongside the solid-state structure of 2 in Fig.…”

New molecular architectures containing low-valent cluster centres with di- and trimetalated 2-vinylpyrazine ligands: synthesis and molecular structures of Ru5(CO)15(μ5-C4H2N2CHCH)(μ-H)2 and Ru8(CO)24(μ7-C4H2N2CHC)(μ-H)3

“…These data, which conrm the regiochemical preference for a hydride to share a common Ru-Ru bond with the edge-bridging benzylidene moiety, are not unlike those recently reported by us in heterocyclic-bridged triosmium clusters. 25 The uxional behavior of the two hydrides in 2 was computationally investigated, and the scrambling of both hydrides about the Ru 3 core proceeds through species B. 26 This transient intermediate B effectively facilitates the exchange of both hydrides about the benzylidene-bridged Ru-Ru bond and one of the two other Ru-Ru bonds in 2.…”