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.

Pressure-induced absorption in nonpolar gases containing tetrahedral molecules

Abstract: The theory of pressure-induced absorption of far infrared radiation by gases is extended to include the contribution of the dipole moment induced in a molecule by the field gradient due to its neighbours. This dipole is nonzero when the molecule lacks a centre of inversion, as in a tetrahedron. In the collision of two tetrahedra, the dipole induced in molecule 2 by the electric field of the octopole moment Ω1 of the partner leads to transitions in which ΔJ(1) = 0, ± 1, ±2, ±3, and ΔJ(2) = 0. The dipole induced by the field gradient of Ω1 leads to ΔJ(1) = 0, ±1, ±2, ±3, and ΔJ(2) = 0, ±1, ±2, ±3, and therefore gives a required increase in absorption at higher frequencies. The field-gradient contribution vanishes in a collision involving a tetrahedral and a spherical molecule. General expressions are given for the field-gradient contributions to the integrated intensity and to the −2 spectral moment.

Anisotropic potentials from the rainbow scattering of sodium atoms and tetrahedral molecules

Abstract: Differential cross sections have been measured for Na scattered by the tetrahedral molecules SiCl4, C(CH3)4, Si(CH3)4 and Sn(CH3)4 in the thermal energy range. Due to the high velocity resolution (Δg/g≈4 per cent) the rainbow structure with primary and at least one secondary rainbow has been resolved. The broadening and quenching of this structure has been used for the determination of the anisotropy of the interaction potential. The corresponding calculations are based on two different formulations of the sudden approximation. It is observed that due to a compensation of repulsive and attractive forces the rainbow scattering determines an effective anisotropy, αeff, which is found to increase for the tetramethyl molecules from 0·2 to 0·7 with increasing size of the central atom, whereas the value for SiCl4 is 0·9 in contrast to the behaviour of other tetrachlorides.

Spodium bonding in five coordinated Zn(II): a new player in crystal engineering?

Abstract: This manuscript evidences the existence and importance of spodium bonds (SpB) in solid state structures involving five-coordinated square-pyramidal Zn(II) spodium atoms Four families of compounds have been found analysing the Cambridge structural database (CSD) where the interaction is very important to understand the crystal packing: (i) multi-dentate Schiff-base complexes, (ii) Zn-porphyrins, (iii) aza-crown ethers and (iv) polyoxometalates, the latter as SpB acceptors The square-pyramidal around the metal center facilitates the approximation of the electron rich atom (ElR) to the Zn(II), contrariwise to the four-coordinated tetrahedral geometry where the steric crowd of the Zn ligands usually impedes the formation of the SpB This highlight concentrates on the SpB interaction, which is different from the classical coordination bond in the sense that Y–Sp⋯A distances are longer (around the sum of van der Waals radii), the interaction weaker and it involves the σ* orbital of the Y–Sp bond (Y = any atom) A theoretical study on one representative family of compounds (Zn-porphyrins) has been also carried out indicating that the SpB energies range from −1 to −74 kcal mol−1 Finally, a statistical analysis of the CSD evidences that the interaction can be somewhat directional