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.

Influence of the angle-dependent part of the dispersion forces on the thermodynamical and spectral properties of gaseous SF6

Abstract: Analytical expressions for the electrostatic, dispersion and induction interaction between an octahedral molecule and an atom, a linear, tetrahedral, or octahedral molecule are deduced from previous work of the present authors concerning the tetrahedral molecules. This allows the calculation of the second pressure and dielectric virial coefficients, the spectral moments of the pressure induced far infra-red absorption band and the intermolecular mean squared torque for a gas of molecules belonging to the Oh group. Numerical applications to SF6 gas show that the anisotropic dispersion interaction contribution plays a dominant role in the virial coefficients but not in the spectral moments. It follows that the order of magnitude of the hexadecapole moment for SF6, previously determined by Rosenberg and Birnbaum from the spectral moments is practically unaffected by consideration of the anisotropic dispersion interaction. In contrast, the calculated values of the virial coefficients are modified significantl...

The crystal structure of a heterobimetallic crown ether complex: [Na(dibenzo-18-crown-6)][FeCl4]

Abstract: Slow evaporation of a solution of ferric chloride and dibenzo-18-crown-6 in 3∶1 CH3CN∶CH3OH produced single crystals of the title complex. This heterobimetallic crown ether complex, [Na(dibenzo-18-crown-6)][FeCl4], crystallizes in the monoclinic space group P2t/n with cell parameters (at 22°C)a=14.608(6),b=10.466(9),c=17.276(9)A, β=91.47(6)°, andDcalc=1.46 g cm−3 for Z=4. The structure consists of discrete ions with the shortest Na ... Cl distance a lengthy contact of 3.56(1)A. The average Na...O separation is 2.69(3)A. The [FeCl4]− anion exhibits a distorted tetrahedral geometry with an average Fe−Cl bond length of 2.16(2)A.

A comparison of the crystal structures of (dabcoH2)CuCl4 and (dabcoH2)CuCl4.H2O

Abstract: The crystal structures of the anhydrous and monohydrated (dabcoH2)CuCl4⋅nH2O salts (n = 0,1) have been determined and a comparison of their crystal structures has been reported. The anhydrous salt is monoclinic P21/c with a = 9.045(2) A, b = 6.9270(10) A, c = 18.767(4) A and β = 90.07(3)° with V = 1175.8(4) A3. The hydrated salt is also monoclinic P21/c with a = 9.266(2) A, b = 9.395(2) A, c = 14.386(3) A and β = 93.32(3)° with V = 1250.3(5) A3. The structures of the two salts are closely related. Both compounds contain isolated distorted (compressed) tetrahedral CuCl4 2− anions, diprotonated dabco cations, and in the case of the hydrated salt, lattice H2O molecules. In the anhydrous salt, each of the two N–H+ groups of the dabcoH2 2+ dications form bifurcated hydrogen bonds to chloride ions on adjacent CuCl4 2− anions along the c axis, thus forming chains running parallel to the c axis. In the hydrated salt, a water molecule is inserted into one of the pair of bifurcated hydrogen bonds, forming instead N–H ⋅ ⋅ ⋅ O–H ⋅ ⋅ ⋅ CuCl4 2− linkages. The chains thus formed are cross-linked by O–H ⋅ ⋅ ⋅ Cl hydrogen bonds between the chains. Because of this additional hydrogen bonding, the CuCl4 2− anions in the hydrated salt are distorted further from tetrahedral geometry.

X-ray absorption fine structure study of multinuclear copper(I) thiourea mixed ligand complexes

Abstract: X-ray absorption fine structure spectra of five copper(I) thiourea complexes [Cu4(thu)6 (NO3)4 (H2O)4] (1), [Cu4(thu)9 (NO3)4 (H2O)4] (2), [Cu2(thu)6 (SO4) H2O] (3), [Cu2(thu)5 (SO4) (H2O)3] (4), and [Cu(thu)Cl 0.5H2O] (5) have been investigated. Complexes 1 and 3 are supposed to have one type of copper centers in trigonal planar and tetrahedral environment, respectively. Complexes 2 and 4 are supposed to have two types of copper centers, one center having trigonal planar geometry and another center having tetrahedral geometry. The aim of the present work is to show how extended X-ray absorption fine structure (EXAFS) spectra of these complexes, having different types of coordination environment, can be analyzed to yield the coordination geometry around one type of copper centers present in complexes 1 and 3, and two types of copper centers present in complexes 2 and 4. The crystal structure of complex 5 is unavailable due to inability of growing its single crystals, and hence the coordination geometry of this complex has been determined from EXAFS. The structural parameters determined from the EXAFS spectra have been reported and the coordination geometry has been depicted for the metal centers present in all the five complexes. Also, the chemical shifts have been used to determine the oxidation state of copper in these complexes. The X-ray absorption near edge spectra features have also been correlated with the coordination geometry. Also, the presence of both three and four coordinated Cu(I) centers in complexes 2 and 4 has been suggested from a comparison of the intensity of the feature at 8984 eV with those of 1 and 3. Further, in case of complex 5, the high intensity of peak A at 8986.5 eV is found to correspond to the presence of Cl coordinated to the copper center.