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: It is found that the persulfoxy sulfur becomes less sulfonium-ion-like in character with decreasing ring size, and it is speculated that the anticipated ring strain effect in the Persulfoxide is compensated for by a weaker sulfur-oxygen interaction and the corresponding relaxation of the need to attain the energetically preferred tetrahedral geometry.
Abstract: Ab initio methods are used to investigate ring strain effects on sulfide-singlet oxygen reaction intermediates. The optimized persulfoxide and thiadioxirane structures derived from 3-, 4-, and 5-membered ring sulfides showed minor albeit systematic changes in geometry. These persulfoxides and thiadioxiranes are best described as distorted tetrahedral and trigonal bipyramidal in nature, respectively. We find that the persulfoxy sulfur becomes less sulfonium-ion-like in character with decreasing ring size. In addition, the persulfoxide and the thiadioxirane are nearly isoenergetic in all cases and their interconversion barriers are nearly identical. We speculate that the anticipated ring strain effect in the persulfoxide is compensated for by a weaker sulfur-oxygen interaction and the corresponding relaxation of the need to attain the energetically preferred tetrahedral geometry.
20 citations
TL;DR: In this article, the sterically demanding bidentate ligand N-ethyl-2-(2′-hydroxy-3′-methylphenyl)-benzimidazole (H-ehmpb) is reported.
20 citations
TL;DR: In this article, the preparation of phenylcyanamidocopper (I) complexes of the types [Cu2(dppe)3L2]·2Me2CO [dppe = 1,2-bis(diphenylphosphino)ethane, L = a phenylcyclanamide ion] and [{Cu(PPh3)2L}2] are described.
Abstract: The preparations of phenylcyanamidocopper(I) complexes of the types [Cu2(dppe)3L2]·2Me2CO [dppe = 1,2-bis(diphenylphosphino)ethane, L = a phenylcyanamide ion] and [{Cu(PPh3)2L}2] are described. The crystal structures of two of the complexes, namely [Cu2(dppe)3(4-ClC6H4NCN)2]·2Me2CO (4-ClC6H4NCN = 4-chlorophenylcyanamide) and [{Cu(PPh3)2(4-MeC6H4NCN)}2](4-MeC6H4NCN = 4-methylphenylcyanamide) have been determined by X-ray diffraction techniques. Crystals of [Cu2(dppe)3(4-ClC6H4NCN)2]·2Me2CO are orthorhombic, space group Pbca, with a= 22.397(14), b= 18.970(7), c= 20.341(5)A and Z= 4. The complex contains centrosymmetric dppe-bridged dinuclear molecules. Each copper atom has a distorted tetrahedral geometry with the cyano nitrogen from a terminally bound [4-ClC6H4NCN]– ligand [Cu–N 1.967(5)A], two phosphorus atoms from a chelating dppe and one from the bridging dppe making up the co-ordination sphere. Crystals of [{Cu(PPh3)2(4-MeC6H4NCN)}2] are monoclinic, space group P21/n, with a= 15.003(2), b= 13.844(2), c= 18.711(2)A, β= 101.22(1)° and Z= 2. This complex is a centrosymmetric dimer with the [4-MeC6H4NCN]– ligands bridging in a µ-1,3 fashion. Each copper atom has a distorted tetrahedral geometry, being bound to two PPh3 phosphorus atoms, a terminal cyano nitrogen atom from a [4-MeC6H4NCN]– ligand [Cu–N 2.045(2)A] and an amido nitrogen from the centrosymmetrically related [4-MeC6H4NCN]– ligand [Cu–N 2.095(2)A]. The v(CN) stretching vibration for the co-ordinated phenylcyanamides occurs in the 2125–2175 cm–1 range. Solid-state cross-polarisation magic-angle-spinning (CP-MAS)31P NMR spectra at 121.47 MHz for the complexes [{Cu(PPh3)2L}2](L = XC6H4NCN; X = 4-Me, 4-Cl or H) consist of two well resolved quartets of doublets arising from each of the crystallographically independent phosphorus nuclei. The doublet structure is a consequence of homonuclear phosphorus–phosphorus two-bond coupling [2J(P1–P2)= 120 Hz]. Available structural data for phenylcyanamidocopper complexes are summarised and comparison made with related pseudohalide complexes.
20 citations
TL;DR: In this article, a template condensation of quinoxaline-2-carboxaldehyde, L-histidine, and metal compound was used to synthesize Schiff base complexes.
Abstract: New Schiff base complexes of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) were synthesized by template condensation of quinoxaline-2-carboxaldehyde, L-histidine, and the metal compound, and were characterized by elemental analysis, fourier transform infrared spectroscopy, electronic spectra, conductance measurements, magnetic susceptibility measurements, ESR spectra, and thermal analysis. In all the complexes, the Schiff base coordinates through azomethine nitrogen, quinoxaline nitrogen, and carboxylato oxygen. The physicochemical and spectroscopic measurements reveal square planar geometry for the copper(II) complex, tetrahedral geometry for the manganese(II), cobalt(II), and zinc(II) complexes, and octahedral geometry for the iron(III) and nickel(II) complexes.
20 citations
TL;DR: In this article, a model of tetrahedral molecules, such as methane, adsorbed in a monolayer at a flat surface such as graphite, is used to investigate a molecular dynamics simulation method.
Abstract: The molecular dynamics simulation method is used to investigate a model of tetrahedral molecules, such as methane, adsorbed in a monolayer at a flat surface, such as graphite. The model consists of 64 octopoles arranged in a planar triangular lattice, with nearest neighbour interactions, and with an external (surface) field applied. The equations of motion are framed entirely in terms of quaternion parameters. Orientational order parameters, and thermodynamic properties, are monitored, and a single phase transition, from a rotationally ordered to a disordered state, with a broad anomaly in the heat capacity, is observed.
20 citations