Synthesis, Reactivity, and Catalytic Activity of Triangular ZrM₂(M = Rh, Ir) Early−Late Heterobimetallic Complexes

Abstract

SummaryReactions of the zirconium-sulfide metallocene anion [Cp tt 2 ZrS 2 ] 2-(Cp tt = η 5 -1,3-di-tertbutylcyclopentadienyl) with [{M(µ-Cl) with one molar-equiv of bis(diphenylphosphino)methane (dppm) gave the cisoid complexes [Cp tt 2 Zr(µ 3 -S) 2 {M(CO)} 2 (µ-dppm)] (M = Rh (9), Ir) with evolution of carbon monoxide.Monodentate phosphites, P(OMe) 3 and P(OPh) 3, react with 6 to give mixtures of the transoid and cisoid isomers [Cp tt 2 Zr(µ 3 -S) 2 {Rh(CO)(P(OR) 3 )} 2 ], which also exhibit a restricted rotation of the Cp tt rings. The molecular structures of complexes 6 and 9 have been determined by X-ray diffraction methods. Compound 6 in the presence of P-donor ligands, P(OMe) 3 , P(OPh) 3, and 40 PPh 3 , is a precursor of catalyst for the hydroformylation of oct-1-ene under mild conditions of pressure and temperature.

Reactivity of [TiM2] (M = Rh, Ir) and [TiIr3] early-late heterobimetallic sulfido-bridged clusters

“…The use of an equimolecular molar ratio of 10:DMAD led to mixtures of 11 and the starting complex 10, while no intermediates were detected by NMR spectroscopy.The mass spectra of 11 and 12 showed peaks at m/z 1382 and 1437, respectively, with an isotopic distribution in agreement with the proposed formulae [CpTi(S)3 Ir 3 (alkyne) 2 (CO) 3 (PMe 3 ) 3 ] (alkyne = DMAD(11), DEAD(12), which incorporation of two molecules of alkyne into the heterotetranuclear cluster 10, upon removal of the bridging carbonyl ligand.The presence of an iridacyclobutenone fragment in both clusters was unambiguously established by NMR spectroscopy and further confirmed by the determination of the molecular structure of 11 by an X-ray diffraction study. The 1 H NMR spectrum of 11 showed four singlets for the methyl protons of the coordinated alkyne moieties, indicating their chemical non-equivalence in the molecule.…”

“…The reactions with activated alkynes, such as dimethyl acetylenedicarboxylate (or diethyl acetylenedicarboxylate) afford clusters [CpTi(µ 3 -S) 3 Ir 3 (µ 2 -η 1 -RO 2 CC=CCO 2 R){C(O)RO 2 CC=CCO 2 R}(CO) 3 (PMe 3 ) 3 ] (R = Me (11), Et (12)), which incorporate two molecules of alkyne. The X-ray molecular structure of 11 shows that one alkyne is cis-metallated to the metal-metal bonded iridium centres whereas the other is taking part of a iridacyclobutenone moiety resulting from the CO migratory insertion into a iridium-alkyne bond at the third iridium centre.…”

“…11 Noteworthy, the carbonyl iridium complex [Cp tt 2 Zr(µ 3 -S) 2 {Ir(CO) 2 } 2 ] is a precursor for the synthesis of early-late heterotrimetallic (ELHT) clusters with [ZrIrM] (M = Rh, Pd, Au) metal cores by metal exchange reactions. 12 We have reported the strong influence of electronic and steric effects imparted by the early metal fragment in the outcome of oxidative addition reactions on [TiIr 2 ] and M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 5 could facilitate the coordination of other substrates. However the electrophilic reagent (H + ) may also protonate the late metals (d 8 ), a process that could lead to the formation of hydrido complexes, especially in the case of the iridium cluster 2.…”

[IrCl{N(CHCHPtBu2)2}]−: a versatile source of the IrI(PNP) pincer platform

“…17 Accordingly, the dihalodicarbonyl anions of iridium are known for a long time and play an important role in catalytic carbonylation reactions. 18 In our case, the combination of steric protection and electronic flexibility provided by the pincer ligand effectively stabilizes the unusually electron rich anionic complex and the complete Ir I /Ir II /Ir III redox series.…”

Early (Ti, Zr)-late (Rh, Ir) heteronuclear complexes with bridging sulphido ligands

“…The rotamers, eclipsed and staggered, due to a hindered rotation of the cyclopentadienyl rings and the relative disposition of the Cp tt groups in the sandwich moiety [38]. The two rotamers interconvert for the complexes with diolefin = nbd and tfbb, whilst no interconversion occurs for the cod complexes, which can be isolated as the pure staggered rotamer.…”