Density functional theory of the CuA-like Cu2S2 diamond core in Cu 2 I I(NGuaS)2Cl2

• Published in: Journal of computational chemistry Vol. 37; no. 11; p. 1005
• Main Authors: Witte, M, Gerstmann, U, Neuba, A, Henkel, G, Schmidt, W G
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc 30.04.2016
• Subjects: Antiferromagnetism; Basis functions; Broken symmetry; Copper; Coupling; Density; Density functional theory; Diamonds; Dispersion; Electron paramagnetic resonance; Electronic structure; Exchanging; Ground state; Kinetic energy; Mathematical analysis; Orbitals; Oxidase; Resonance; Symmetry; Wave dispersion
• DOI: 10.1002/jcc.24289
• ISSN: 0192-8651

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)2Cl2 [NGuaS=2-(1,1,3,3-tetramethylguanidino) benzenethiolate, C11H16N3S] 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 [Cu2+...Cu2+] site in which the coupling is driven by super exchange interaction within the Cu2S2 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 CuCu distance close to the experimentally observed value of 2.7 Å. For the negative charge state of the complex, a mixed-valent [Cu1.5+...Cu1.5+] electronic structure with a smaller CuCu distance of 2.6 Å is predicted, similar to the value of the CuA site of cytochrome c oxidase. © 2016 Wiley Periodicals, Inc.