Topic
Tetrahedral molecular geometry
About: Tetrahedral molecular geometry is a research topic. Over the lifetime, 1795 publications have been published within this topic receiving 30706 citations.
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TL;DR: The geometric preferences of a family of four coordinate, iron(II) d6 complexes of the general form L2FeX2 have been systematically evaluated and tetrahedral and square planar coordination has been observed upon complexation of chelating phosphine ligands.
Abstract: The geometric preferences of a family of four coordinate, iron(II) d6 complexes of the general form L2FeX2 have been systematically evaluated. Treatment of Fe2(Mes)4 (Mes = 2,4,6-Me3C6H2) with monodentate phosphine and phosphite ligands furnished square planar trans-P2Fe(Mes)2 derivatives. Identification of the geometry has been accomplished by a combination of solution and solid-state magnetometry and, in two cases (P = PMe3, PEt2Ph), X-ray diffraction. In contrast, both tetrahedral and square planar coordination has been observed upon complexation of chelating phosphine ligands. A combination of crystallographic and magnetic susceptibility data for (depe)Fe(Mes)2 (depe = 1,2-bis(diethylphosphino)ethane) established a tetrahedral molecular geometry whereas SQUID magnetometry and Mossbauer spectroscopy on samples of (dppe)Fe(Mes)2 (dppe = 1,2-bis(diphenylphosphino)ethane) indicated a planar molecule. When dissolved in chlorinated solvents, the latter compound promotes chlorine atom abstraction, forming te...
110 citations
TL;DR: In this paper, the authors reported results of UV-Vis spectrophotometric and synchrotron XAFS experiments of ferric chloride complexes in chloride concentrations up to 15 m and at temperatures of 25-90 °C.
108 citations
TL;DR: Analysis of reduced orbital charges and spin densities obtained from DFT calculations suggests that the electronic structures of 1-3 are best described as either a high-spin Fe(II) ion coordinated to two radical monoanions (2) or as an intermediate- spin Fe(III) ioncoordinated to one radical Monoanion and one closed-shell dianion (1, 3).
Abstract: The four-coordinate heteroleptic complex [FeIII(Fpda2−)(Fdad•−)] (1) and its homoleptic analogue [FeII(Fdad•−)2] (2), where Fpda2− is the closed-shell ligand N,N′-bis(pentafluorophenyl)-o-phenylenediamide(2−) and Fdad•− is the singly reduced N,N′-bis(pentafluorophenyl)-2,3-dimethyl-1,4-diazabutadiene π-radical anion, have been synthesized. X-ray crystallographic studies reveal a twisted tetrahedral geometry of the FeN4 coordination polyhedron in both 1 and 2. The electronic structures of 1 and 2 were probed by magnetic susceptibility measurements, 57Fe Mossbauer and electronic spectroscopy, and density functional theory (DFT) calculations. In spite of their similar geometries and a common triplet ground state (St = 1), the electronic structures of 1, 2, and the previously reported homoleptic analogue [FeIII(Fpda2−)(Fpda•−)] (3), where Fpda•− is a one-electron-oxidized form of Fpda2−, differ. The electronic structure of 2 consists of two Fdad•− radicals coupled antiferromagnetically to a high-spin FeII cen...
106 citations
TL;DR: The data for these complexes collectively suggest that the [PhBP(3)] ligand provides an unusually strong ligand-field to these divalent cobalt complexes that is chemically distinct from typical tris(phosphine) donor ligand sets, and distinct from tridentate borato ligands that have been previously studied.
Abstract: We have prepared a series of divalent cobalt(II) complexes supported by the [PhBP3] ligand ([PhBP3] = [PhB(CH2PPh2)3]-) to probe certain structural and electronic phenomena that arise from this strong field, anionic tris(phosphine) donor ligand. The solid-state structure of the complex [PhBP3]CoI (1), accompanied by SQUID, EPR, and optical data, indicates that it is a pseudotetrahedral cobalt(II) species with a doublet ground statethe first of its type. To our knowledge, all previous examples of 4-coordinate cobalt(II) complexes with doublet ground states have adopted square planar structure types. Complex 1 provided a useful precursor to the corresponding bromide and chloride complexes, {[PhBP3]Co(μ-Br)}2, (2), and {[PhBP3]Co(μ-Cl)}2, (3). These complexes were similarly characterized and shown to be dimeric in the solid-state. In solution, however, the monomeric low spin form of 2 and 3 dominates at 25 °C. There is spectroscopic evidence for a temperature-dependent monomer/dimer equilibrium in solution f...
104 citations
TL;DR: The superconducting properties of the lanthanide LnNi2B2C phases are attributed to an electron-phonon mechanism in which high frequency boron a1g optical phonons dynamically modulate the tetrahedral NiB4 bond angles as mentioned in this paper.
100 citations