Are formal oxidation states above one viable in cyclopentadienylcopper cyanides?
ABSTRACT Recent experiments have led to the discovery of the thermally unstable organocopper compounds (η(3)-C(3)H(5))CuMe(2), [(η(3)-C(3)H(5))CuMe(3)](-), and CuMe (4)(-) in which the copper atom is in the +3 formal oxidation state. In a quest for more stable organocopper compounds with copper in formal oxidation states above one, the binuclear cyclopentadienylcopper cyanides Cp(2)Cu(2)(CN)(n) (Cp = η(5)-C(5)H(5); n = 1, 2, 3) have been studied using density functional theory (DFT). The lowest energy structures are found to have terminal Cp rings and bridging cyanide ligands up to a maximum of two bridges. Higher-energy Cp(2)Cu(2)(CN)(n) (n = 1, 2, 3) structures are found with bridging Cp rings. The Cp(2)Cu(2)(CN)(3) derivatives, with the copper atoms in an average +2.5 oxidation state, are clearly thermodynamically disfavored with respect to cyanogen loss. However, Cp(2)Cu(2)(CN)(2) and Cp(2)Cu(2)(CN), with the copper atoms in the average oxidation states +1.5 and +2, respectively, are predicted to have marginal viability. The prospects for the copper(II) derivative Cp(2)Cu(2)(CN)(2) contrast with that of the "simple" Cu(CN)(2), which is shown both experimentally and theoretically to be unstable with respect to cyanogen loss to give CuCN.
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ABSTRACT: In this review we highlight recent progress in DFT/TDDFT application to copper coordination compounds. Selected most recent applications that best illustrate the promise of DFT in the following active areas of copper coordination chemistry: (i) mechanistic studies of copper-catalyzed reactions, (ii) investigating the nature of bonding in copper coordination compounds, (iii) the bioactivity and biochemistry of copper coordination compounds and (iv) the photophysics (absorption and emission spectra) of copper coordination compounds are reviewed. This review is intended to be of interest to both experimentalists and theorists in the expanded field of copper coordination chemistry.RSC Advances 07/2014; 4(61). DOI:10.1039/C4RA04921G · 3.84 Impact Factor
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ABSTRACT: Theoretical studies predict the lowest energy structures of the binuclear cyclopentadienylrhenium hydrides Cp2Re2H n (Cp = η5–C5H5; n = 4, 6, 8) to have a central doubly bridged Re2(μ–H)2 unit with terminal η5–Cp rings and the remaining hydrides as terminal ligands. However, the lowest energy Cp2Re2H2 structure by more than 12 kcal mol−1 has one terminal η5-Cp ring, a bridging η3,η2–Cp ring, and two terminal hydride ligands bonded to the same Re atom. The lowest energy hydride-free Cp2Re2 structure is a perpendicular structure with two bridging η3,η2–Cp rings. The previously predicted bent singlet Cp2Re2 structure with terminal η5-Cp rings and a formal Re–Re sextuple bond lies ∼37 kcal mol−1 above this lowest energy (η3,η2–Cp)2Re2 structure. The thermochemistry of the CpReH n and Cp2Re2H n systems is consistent with the reported synthesis of the permethylated derivatives Cp*ReH6 and Cp*2Re2H6 (Cp* = η5–Me5C5) as very stable compounds. Additionally, natural bond orbital analysis, atoms-in-molecules and overlap population density-of-state in AOMIX were applied to present the existence of rhenium–rhenium multiple bonds.Journal of Molecular Modeling 07/2015; 21(1):2546. DOI:10.1007/s00894-014-2546-4 · 1.87 Impact Factor