Catalysis by the serine proteinases proceeds via a tetrahedral intermediate whose oxyanion is stabilized by hydrogen-bonding in the oxyanion hole. There have been extensive 13C-NMR studies of oxyanion and tetrahedral intermediate stabilization in trypsin, subtilisin and chymotrypsin using substrate-derived chloromethane inhibitors. One of the limitations of these inhibitors is that they irrever...

The synthesis of the M[(OPPh(2))(SePPh(2))N](2), M = Co (1), Ni (2) complexes was accomplished by metathetical reactions between the corresponding M(II) salts and the deprotonated form of the dichalcogenated imidodiphosphinato ligand [(OPPh(2))(SePPh(2))N](-). X-Ray crystallography revealed a pseudo-tetrahedral MO(2)Se(2) coordination sphere, owing to the asymmetric (O,Se) nature of the chelati...

We have prepared a series of divalent cobalt(II) complexes supported by the [PhBP(3)] ligand ([PhBP(3)] = [PhB(CH(2)PPh(2))(3)](-)) to probe certain structural and electronic phenomena that arise from this strong field, anionic tris(phosphine) donor ligand. The solid-state structure of the complex [PhBP(3)]CoI (1), accompanied by SQUID, EPR, and optical data, indicates that it is a pseudotetrah...

Dicationic tetranuclear ruthenium octahydride [(Cp*Ru)4H8]2+ (5) with tetrahedral geometry was obtained by reaction of dinuclear ruthenium tetrahydride (Cp*Ru)2(μ-H)4 (1) with an excess of Brønsted acids, such as HBF4·OEt2, in toluene. Monocationic tetraruthenium heptahydride [(Cp*Ru)4H7]+ (7) was obtained by dropwise addition of a diluted acid to a rigorously stirred solution of 1 at ambient t...

Two new mononuclear complexes, [Cu2Cl1.23(NO3)0.77(Ampy)4(H2O)4](NO3)2·4H2O (I) and [CdI2(Ampy)2] (II) (Ampy = 4-amino-6-methoxypyrimidine) have been synthesized characterized by single crystal X-ray diffraction studies (CCDC nos. 2023331 (I), (II)) at 295 K for 100 (II). The structure of the Cu(II) complex shows that central atom is five-coordinated with a distorted square pyramidal geometry. ...

The new Schiff base ligand has been prepared viacondensation reaction of o-aminoacetophenonoximeand3-Ethoxysalicylaldehyde. This characterized by different techniques such as, (IR, U.V-Vis) spectroscopy, (1H, 13C) NMR spectra, GC-Mass spectrum and micro-elemental analysis. Its Cr(III), Mn(II), Co(II), Ni(II) Cu(II) complexes magnetic susceptibility, conductivity measurements atomic absorption. ...

Here we report the syntheses and crystal structures of a series of cobalt(II) and nickel(II) complexes derived from (R)NP2 ligands (where R = OMe(Bz), H(Bz), Br(Bz), Ph) bearing ethylene linkers between a single N and two P donors. The Co(II) complexes generally adopt a tetrahedral configuration of general formula [(NP2)Co(I)(2)], wherein the two phosphorus donors are bound to the metal center ...

A procedure to quantify the distortion (quality) of a high-order mesh composed by curved tetrahedral elements is presented. The proposed technique has two main applications. First, it can be used to check the validity and quality of a high-order tetrahedral mesh. Second, it allows the generation of curved meshes composed by valid and high-quality high-order tetrahedral elements. To this end, we...