title: Density functional theory of the CuA -like Cu2 S2 diamond core in Cu 2II(NGuaS)2 Cl2.
abstract: Density functional theory (DFT) calculations with localized as well as plane-wave basis functions are performed for the recently reported dicopper thiolate species Cu2 (NGuaS)2 Cl2 [NGuaS = 2-(1,1,3,3-tetramethylguanidino) benzenethiolate, C11 H16 N3 S] and its bromo derivative [Neuba et al., Angew. Chem. Int. Ed. 2012, 51, 1714.]. For both hybrid and semilocal functionals, the neutral complexes are found to have broken symmetry (BS) character, with electron paramagnetic resonance silent, antiferromagnetically coupled [Cu(2+) …Cu(2+) ] site in which the coupling is driven by super exchange interaction within the Cu2 S2 diamond core. The accurate theoretical description of the geometric structure, however, provides a major challenge for DFT: (i) the multideterminant character of the ground state wave function has to be covered by the BS approach. It requires (ii) metageneralized gradient approximations, that is hybrid functionals with an explicit dependence on the kinetic energy of the individual orbitals: In combination with a dispersion correction, the metafunctional TPSSh results in a CuCu distance close to the experimentally observed value of 2.7 Å. For the negative charge state of the complex, a mixed-valent [Cu(1.5+) …Cu(1.5+) ] electronic structure with a smaller CuCu distance of 2.6 Å is predicted, similar to the value of the CuA site of cytochrome c oxidase.
authors.affiliation: Department of Physics, Lehrstuhl Für Theoretische Materialphysik, Universität Paderborn, Paderborn, 33098, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Witte
authors.affiliation: Department of Physics, Lehrstuhl Für Theoretische Materialphysik, Universität Paderborn, Paderborn, 33098, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Gerstmann
authors.affiliation: Department of Chemistry, Lehrstuhl Für Anorganische Chemie, Universität Paderborn, Paderborn, 33098, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Neuba
authors.affiliation: Department of Chemistry, Lehrstuhl Für Anorganische Chemie, Universität Paderborn, Paderborn, 33098, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Henkel
authors.affiliation: Department of Physics, Lehrstuhl Für Theoretische Materialphysik, Universität Paderborn, Paderborn, 33098, Germany.
authors.forename: W G
authors.initials: WG
authors.lastname: Schmidt
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D015394:Molecular Structure; D011789:Quantum Theory
chemical_list: D056831:Coordination Complexes; C000612306:Cu2(2-(1,1,3,3-tetramethylguanidino)benzenethiolate)2Cl2; D003300:Copper
keywords: CuA site; DFT; broken symmetry; dicopper thiolate; super exchange