Andrew A. Cherkas

Carbon-13 NMR shifts of bridging acetylides in polynuclear complexes

Abstract Carbon-13 NMR data for a range of iron group polynuclear acetylide complexes with μ 2 -η 2 , μ 3 -η 2 and μ 4 -η 2 alkynyl groups are presented. For doubly bridging μ 2 -η 2 -acetylides of Fe, Ru and Os, the C α resonance lies in the range 65–110 ppm downfield of TMS, while C β shifts cover the range 90–110 ppm. In μ 3 -η 2 -complexes C α lies in the region 115–220 ppm and is always downfield of C β (43–153 ppm). For μ 4 -η 2 -acetylides, C α , is also downfield of C β with values lying in the ranges 185–230 and 91–165 ppm, respectively. Comments on the most appropriate experimental parameters for the observation of 13 C spectra of acetylides and techniques for assigning resonances are included.

Electron rich acetylide clusters; molecular and electronic structure and reactions of Os3(CO)7(µ2-η2-CCR)2(µ-PPh2)2(R = Ph, Pri); 50-electron species with expanded metal frameworks

The reactivity of the 50-electron acetylide clusters Os3(CO)7(µ2-η2-CCR)2(µ-PPh2)2[(1a) R = Ph; (1b) R = Pri] which have unusual expanded Os3 frameworks, is dominated by nucleophilic addition at the metals: the molecular structures of Os3(CO)7(µ2-η2-CCPri)2(µ-PPh2)2 and the ethylamine adduct of (1a), Os3(CO)6(µ2-η2-CCPh)(η1-CCPh)(µ-PPh2)2(EtNH2)2(2a) have been determined by X-ray diffraction and their electronic structures probed by EHMO calculations.

Carbon-13 NMR shifts of bridging hydrocarbyls derived from the addition of nucleophiles to complexed organic ligands in DI- and polynuclear complexes

Abstract 13 C NMR data for a range of iron group dinuclear hydrocarbyl fragments derived from nucleophilic addition to μ 2 -η 2 -acetylides and other complexed organic ligands are presented. For μ 2 -vinylidenes C α resonances lie in the range 292.2–297.2 ppm, while C β resonances have chemical shifts of 113.3–145.31 ppm. For μ 2 -alkylidene complexes the electron rich C α lies in the range 28.8–74.95 ppm with C β shifts of 196.0–215.3 ppm. Two carbon-bridged complexes include phenethylidene complexes with C α resonances in the range 202.0–249.7 ppm and C β resonances between 31.0–44.9 ppm. Zwitter-ionic parallel acetylene complexes have different ranges depending on the nucleophile. Those derived from phosphates have C α in the range 78.2–110.0 ppm and C β 191.3–216.4 ppm, while those derived from isocyanides have C α at 59.7–91.8 ppm and C β at 211.5–241.2 ppm. Allenyl chemical shifts have a wide range but one generally in the order moving upfield δ C β > δ C α > δ C γ . The nucleophilic adducts of the allenyl complex Ru 2 (CO) 6 (μ-η 1 ,η 2 -H 2 CCCPh)(μ-PPh 2 ) are dimetallacyclopentane and dimetallacyclopentene derivatives which give three 13 C chemical shifts in the range 33.4–122.7 ppm for C α , 184.2–207.4 ppm for C β and 0.4–7.7 ppm for C γ . For two carbon-bridged derivatives, the more carbene-like carbon atom has a downfield chemical shift and couples more strongly to a phosphido bridge phosphorus atom. The 13 C chemical shifts and 13 C 31 P coupling constants for these bridging zwitter-ionic hydrocarbyls provide a powerful spectroscopic probe of structure and bonding.

Synthesis of 62-electron square planar clusters with group 15 and 16 main group atoms: Structural characterization of Ru4(CO)11(μ4-PPh)(μ4-S) and Ru4(CO)10(μ4-PPh)(μ4-Se)(PEt3): Bonding preferences in cappingNido Ru4(CO)13(μ3-PPh)

Thecloso octahedral cluster Ru4(CO)11(μ4-PPh)(μ4-S)1 and selenium and tellurium analogues, the first examples of unsaturated ruthenium clusters with a planar metal core and different main group 15 and 16 atoms have been synthesized fromnido Ru4(CO)13(μ3-PPh). An X-ray analysis of1 and Ru4(CO)10(μ4-PPh)(μ4-Se)(PEt3)2a has confirmed thetrans disposition of phosphorus and group 16 main group fragments.

Cluster bound phosphinovinylidenes and phosphinitovinylidenes from alkynilphosphines and their oxides: synthesis and structures of [Ru3(CO)9{μ3-σ,σ,η3-CCCHMe2(PPh2)}] and [Fe3(CO)9{μ3-σ,σ,η3-CCCHMe2(Ph2PO)}]

Abstract The alkynylphosphine Ph 2 PCCCHMe 2 can be converted via the phosphido-acetylide complex Ru 3 (CO) 9 {μ 3 -σ,η 2 -CC(CHMe 2 )}(μ-PPh 2 ) to the isomeric vinylidene cluster [Ru 3 (CO) 9 {μ 3 -σ,σ,η 3 -C CCHMe 2 (P Ph 2 )}] whose structure has been determined by X-ray analysis; the oxide Ph 2 P(O)CCCHMe 2 with Fe 2 (CO) 9 afforded a structurally related cluster [Fe 3 (CO) 9 {μ 3 -σ,σ,η 3 -C CCHMe 2 (Ph 2 PO )}].