Palladium and Platinum Complexes from Methyl(2-Thienyl) Chalcogenides and BIS(2-Thienyl) Dichalcogenides

The preparation of [M(C₄H₃SECH₃)₂Cl₂] (M = Pd, Pt; E = Se, Te) and [Pd₆Te₆(C₄H₃S)₂(PPh₃)₆Cl₂] from methyl(2-thienyl)chalcogenides and bis(2-thienyl) ditelluride is reported. The products are identified and characterized by X-ray crystallography and by ⁷⁷Se and ¹²⁵Te NMR spectroscopy.     

Arnowitt–Deser–Misner representation and Hamiltonian analysis of covariant renormalizable gravity

We study the recently proposed Covariant Renormalizable Gravity (CRG), which aims to provide a generally covariant ultraviolet completion of general relativity. We obtain a spacetime decomposed form—an Arnowitt–Deser–Misner (ADM) representation—of the CRG action. The action is found to contain time derivatives of the gravitational fields up to fourth order. Some ways to reduce the order of these time derivatives are considered. The resulting action is analyzed using the Hamiltonian formalism, which was originally adapted for constrained theories by Dirac. It is shown that the theory has a consistent set of constraints. It is, however, found that the theory exhibits four propagating physical degrees of freedom. This is one degree of freedom more than in Hořava–Lifshitz (HL) gravity and two more propagating modes than in general relativity. One extra physical degree of freedom has its origin in the higher order nature of the CRG action. The other extra propagating mode is a consequence of a projectability condition similarly as in HL gravity. Some additional gauge symmetry may need to be introduced in order to get rid of the extra gravitational degrees of freedom.     

Polymerization of ethylene with new diimine complexes of late transition metals

Three pyridylimine based complexes of Ni^II and Co^II were reacted with methylaluminoxane (MAO) and tested as catalysts in ethylene polymerization. The two nickel catalysts produced mainly methyl branched polymers with good to moderate activity, while the cobalt compound showed only marginal activity. Reaction conditions strongly affect the polymer properties, such as molecular weight, melting temperature, degree of branching, and chain end unsaturation type.