481 research outputs found

    A Two-Coordinate Nickel Imido Complex That Effects Cāˆ’H Amination

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    An exceptionally low coordinate nickel imido complex, (IPr*)Niā•N(dmp) (2) (dmp = 2,6-dimesitylphenyl), has been prepared by the elimination of N_2 from a bulky aryl azide in its reaction with (IPr*)Ni(Ī·^6-C_7H_8) (1). The solid-state structure of 2 features two-coordinate nickel with a linear Cāˆ’Niāˆ’N core and a short Niāˆ’N distance, both indicative of multiple-bond character. Computational studies using density functional theory showed a Niā•N bond dominated by Ni(dĻ€)āˆ’N(pĻ€) interactions, resulting in two nearly degenerate singly occupied molecular orbitals (SOMOs) that are Niāˆ’N Ļ€* in character. Reaction of 2 with CO resulted in nitrene-group transfer to form (dmp)NCO and (IPr*)Ni(CO)_3 (3). Net Cāˆ’H insertion was observed in the reaction of 2 with ethene, forming the vinylamine (dmp)NH(CHā•CH_2) (5) via an azanickelacyclobutane intermediate, (IPr*)Ni{N,C:Īŗ^2-N(dmp)CH_2CH_2} (4)

    Angular Forces Around Transition Metals in Biomolecules

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    Quantum-mechanical analysis based on an exact sum rule is used to extract an semiclassical angle-dependent energy function for transition metal ions in biomolecules. The angular dependence is simple but different from existing classical potentials. Comparison of predicted energies with a computer-generated database shows that the semiclassical energy function is remarkably accurate, and that its angular dependence is optimal.Comment: Tex file plus 4 postscript figure
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