Bw Skelton

Novel cationic and neutral Pd(II) complexes bearing imidazole based chelate ligands: synthesis, structural characterisation and catalytic behaviour

Abstract A variety of neutral and cationic methyl palladium(II) complexes [Pd(CH 3 )(Cl)(L–L)] ( 3 ) and [Pd(CH 3 )(CH 3 CN)(L–L)]BF 4 ( 4 ), containing known and new N -methylimidazole-2-yl (mim) and N -methylbenzimidazole-2-yl (bmim) based chelate ligands (L–L) have been synthesised. The dichloro complexes [Pd(Cl) 2 {(mim) 2 CO}] ( 2b ) and [Pd(Cl) 2 (mim)PPh 2 ] ( 2e ) have also been synthesised. The crystal structures of [Pd(Cl) 2 {(mim) 2 CNPh}] ( 2d ) and [Pd(CH 3 )(Cl){(bmim) 2 CO}] ( 3c ) have been determined and show a square planar geometry at palladium(II) with an appreciable diminished bite angle (85.6°) in 3c compared to 2d (88.5°). The molecular structure of 2d and 3c show both bisimidazole ligands coordinated via the ring nitrogen donors and inclination of the chelate ring bridge to the coordination plane (boat conformation). Low temperature NMR spectra indicate boat-to-boat inversion of the chelate ring in [Pd(CH 3 )(CH 3 CN){(mim) 2 CO}] + ( 4b ). Examples of the neutral and cationic complexes were tested in the Heck reaction and CO/ethylene copolimerisation respectively. The CO bridged bisimidazole complex ( 3b ) exhibited high activity (TON of 100 000) in the Heck reaction whereas the closely related benzimidazole complex 3c was about half as active (TON of 53 000). Low activities were found for the cationic complex 4b in the CO/ethylene copolymerisation (TON 449).

Cluster chemistry. Part 97. Some unusual complexes obtained from reactions of Ru3(μ-dppm)(CO)10 and C7 or C8 hydrocarbons☆

Abstract Among the products of reactions between Ru 3 (μ-dppm)(CO) 10 and impure cycloheptatriene were Ru 3 (μ 3 -C 7 H 8 )(μ-dppm)(CO) 7 ( 3a ) and two isomers of Ru 3 (μ 3 -C 8 H 10 )(μ-dppm)(CO) 7 ( 2b and 3b ). On the basis of crystallographic studies, 2b is judged to be Ru 3 (μ-H) 2 (μ- 3 -C 7 H 5 Me)(μ-dppm)(CO) 7 , containing the novel norbonenyne ligand, while complexes 3 contain cycla ligands. None of these were obtained when purified cycloheptatriene was used.

The Structure of [PdCl2{(Py)2(PyH)CH-N′,N″}][PdCl4]0.5.2H2O (Py = Pyridin-2-yl), a Complex With Protonated 2,2′,2″-Methylidynetrispyridine as a Bidentate Ligand

Crystals of dichloro[2,2′,2″-methylidynetris(pyridin)-1-ium-N′,N″]palladium(II) hemi[tetra-chloropalladate(II)] dihydrate are monoclinic, P21/c, a 8.558(5), b 15.516(7), c 16.153(5) a, P 112.07(4)°, Z 4. The cations [PdCl2{(Py)2(PyH)CH-N′,N″}]+ have square-planar geometry for palladium, with the ligand in a boat conformation and having an uncoordinated protonated pyridine group.

Chloro(phenyl)(1H-pyrazole-kappaN2)(triphenylphosphine-kappaP)palladium(II).

In the title compound, [Pd(C6H5)Cl(C3H4N2){P(C6H5)3}], PdClPh(pyrazole)(PPh3), the phenyl and Cl ligands lie mutually trans. The compound is the first structurally characterized complex with four monodentate Cl, P, N and (non-carbenoid) C ligands in a squareplanar four-coordinate palladium(II) environment. The pyrazole ligand is coplanar with the latter array. The pyrazole NH group forms a bifurcated hydrogen bond to Cl, with an intra and intermolecular component.

Synthesis and X-ray structures of two complexes containing dicarbon (C2) attached to Ru5 clusters with unusual core geometries

Addition of Me2S2 to Ru5(µ5-C2PPh2)(µ-PPh2)(CO)131 resulted in a sequence of Ru–Ru bond cleavage and formation reactions; the structures of two of the products, Ru5(µ-C2)(µ-SMe)2(µ-PPh2)2(CO)123 and Ru5(µ5-C2)(µ-SMe)2(µ-PPh2)2(CO)114, which contain dicarbon (C2) attached to open and closed Ru5 pentagons, respectively, are described.