title: Family of V(III)-tristhiolato complexes relevant to functional models of vanadium nitrogenase: synthesis and electronic structure investigations by means of high-frequency and -field electron paramagnetic resonance coupled to quantum chemical computations.
abstract: A series of V(III) complexes of varying coordination number (5, 6, and 7) all containing the PS3 ligand (PS3 = trianion of tris(2-thiophenyl)phosphine and its derivatives with other phenyl substituents) has been prepared and structurally characterized. The complexes have general formula [V(PS3)L(n)](0,-), where n = 1 (from L = Cl(-), 1-Me-Im, N(3)(-)), 2 (from L = 2,2'-bpy; counting each N of the bidentate ligand), and 3 (from L = 1-Me-Im, N(2)H(4)). The complexes have also been investigated by direct current (DC) magnetic susceptibility and high-frequency and -field electron paramagnetic resonance (HFEPR). HFEPR, supported by magnetometry, has provided accurate spin Hamiltonian parameters that describe the S = 1 spin ground state of the complexes. Of particular interest are the zero-field splitting (zfs) parameters which, together with structural data, are the empirical starting point for detailed computational studies. The computational methods included density functional theory (DFT), which was only marginally successful, and more advanced ab initio methods (CASSCF and SORCI). The zfs in these complexes is relatively small in magnitude (|D| approximately 1 cm(-1)) and is the result of multiple, often counteracting, spin-orbit coupling (SOC) and spin-spin coupling (SSC) contributions. The specific origin of each of these contributions is described in detail. The results indicate the level of electronic structure calculation possible for transition metal complexes even with multiple unpaired electrons and highly covalent, heavier atom donor ligands.
authors.affiliation: Institut für Physikalische und Theoretische Chemie, Universität Bonn, D-53115 Bonn, Germany.
authors.forename: Shengfa
authors.initials: S
authors.lastname: Ye
authors.forename: Frank
authors.initials: F
authors.lastname: Neese
authors.forename: Andrew
authors.initials: A
authors.lastname: Ozarowski
authors.forename: Dmitry
authors.initials: D
authors.lastname: Smirnov
authors.forename: J
authors.initials: J
authors.lastname: Krzystek
authors.forename: Joshua
authors.initials: J
authors.lastname: Telser
authors.forename: Ju-Hsiou
authors.initials: JH
authors.lastname: Liao
authors.forename: Chen-Hsiung
authors.initials: CH
authors.lastname: Hung
authors.forename: Wei-Chen
authors.initials: WC
authors.lastname: Chu
authors.forename: Yi-Feng
authors.initials: YF
authors.lastname: Tsai
authors.forename: Rong-Chin
authors.initials: RC
authors.lastname: Wang
authors.forename: Kun-Yuan
authors.initials: KY
authors.lastname: Chen
authors.forename: Hua-Fen
authors.initials: HF
authors.lastname: Hsu
mesh_terms: D003198:Computer Simulation; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D009591:Nitrogenase / Q000737:chemistry* / Q000378:metabolism; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D011789:Quantum Theory; D013438:Sulfhydryl Compounds / Q000737:chemistry; D014639:Vanadium / Q000737:chemistry
chemical_list: D009942:Organometallic Compounds; D013438:Sulfhydryl Compounds; D014639:Vanadium; D009591:Nitrogenase