In this paper we have prepared a series of Ti(IV), Hf(IV) and Al(III) complexes based on bipyrrolidine salan proligands. The Hf(IV) complexes have all been characterised in the solid-state, the chiral ligands coordinate to Hf(IV) in an a-cismanner whereas themeso ligand coordinates in a b-cis geometry. The Hf(IV) complexes are all active for the ROP of rac-lactide in the melt, with the fluxiona...

Ruthenium methylene/silyl complexes of stoichiometry Cp*2Ru2(μ-CH2)(SiR3)(μ-Cl), where SiR3 ) SiMe3 (1), SiEt3 (2), SiMe2Et (3), and SiMe2Ph (4), are produced when [Cp*RuCl]4 is treated with the appropriate dialkylmagnesium reagent, Mg(CH2SiR3)2. Each complex undergoes two fluxional processes as observed by variable-temperature 1H NMR spectroscopy. The low-temperature exchange process is migrat...

Experimental evidences are presented showing unusually large and highly anisotropic vibrations in the "simple cubic" (SC) unit cell adopted by calcium over a broad pressure ranging from 30-90 GPa and at temperature as low as 40 K. X-ray diffraction patterns show a preferential broadening of the (110) Bragg reflection indicating that the atomic displacements are not isotropic but restricted to t...

Although numerous quantum calculations have been made over the years of the stabilities of the fluxional isomers of C(4)H(7)(+), none have been reported for other than the gas phase (which is unrealistic for these ionic species) that exhibit exceptional fluxional properties in solution. To be sure, quantum-mechanical calculations for solutions are subject to substantial uncertainties, but nonet...

The crystal structure of [PtCl2(cis-1,3-chxn)] (cis-1,3-chxn = (cis-cyclohexane-1,3-diamine)) as the dimethyformamide solvate is reported. When [PtCl2(cis-1,3-chxn)] binds to d(GpG), two isomers are formed that are readily separated by HPLC. Both the HPLC and GFAAS studies of the products show that the isomers form in a 1 : 1 ratio. Competition experiments involving d(GpG) and the aquated and n...

Eight dinuclear Au(i)-carbene complexes have been synthesized from various imidazolium-linked cyclophanes and related acyclic bis(imidazolium) salts, by treatment of the imidazolium salts with [Au(i)(SMe(2))Cl] in the presence of a carboxylate base. Single crystal structural studies showed that the Au(i)-carbene compounds contain dinuclear (AuL)(2) cations in which a pair of gold(i) centres are...

Bis(phenoxy-imine) complexes of zirconium or titanium, a type Fenokishi-Imin catalysts, allow the production polyethylenes with well-defined bimodal molecular weight distributions. Interestingly, by substitution phenyl rings in bis(phenoxy-imine) ligands perfluorinated rings, polymerization reaches desired unimodal behavior. These catalysts have three isomers similar energy that can be easily i...

Shape-shifting molecules such as bullvalene undergo rapid structural reorganizations via degenerate Cope rearrangements. Here, we obtain accurate CCSD(T)/CBS barrier heights and reaction energies for a wide range of rearrangements in substituted bullvalenes (C10H9R, R = NH3, OH, CH3, H, F, Cl, SH, CN). We use this benchmark dataset to evaluate the performance DFT ab initio methods kinetics ther...