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.

On the fragment ion angular distributions arising from the tetrahedral molecule CH3I

Abstract: The mass spectra for both horizontal and vertical polarizations and the angular distributions of fragment ions arising from Coulomb explosion of tetrahedral methyl iodide (CH3I) ions, obtained at a laser intensity of 1016 W cm-2 are presented. All fragment ion distributions are peaked along the direction corresponding to collinearity of the laser electric field with the time-of-flight mass spectrometer axis. The In + ion (n≤7) angular distributions from the dissociation of the parent ions are all of similar widths, which would imply a geometric, as opposed to dynamic, alignment. Additionally, the lower-charged I ions have an isotropic component that decreases as the charge state increases. Measurements of the CHm+ (m≤3), Cp + (p≤4) and H+ ion distributions show that these are also maximal along the polarization direction. Furthermore, there is also a CH22+ ion peak present in the CHm group, which has a distribution similar to those measured for the other ions. This mass peak is the prominent multi-charged ion in this group. As the CH3I molecule is initially tetrahedral, these results suggest that the molecular structure undergoes a change such that the H-C and C-I bonds tend to lie along the field. Several authors have described work which first aligned CH3I molecules with a nanosecond laser and then photodissociated with a femtosecond laser, to produce fragment ion distributions. This is the first time that the angular distributions from a tetrahedral molecule have been presented using femtosecond laser pulses only and in the case of CH3I, for fragments other than CH3+ and I+. The fragment energetics from the single CH3I molecule have been compared with those from recent work dealing with the Coulomb explosion of CH3I clusters.

Interaction of hydrogen and hydrocarbons with transition metals. Neutron diffraction study of the crystal and molecular structure of di-.mu.-hydrido-decacarbonyl-.mu.-methylene-triosmium

Abstract: The crystal and molecular structure of (..mu..-H)/sub 2/Os/sub 3/(CO)/sub 10/(..mu..-CH/sub 2/) has been determined by using single-crystal neutron diffraction. The complex crystallizes in the orthorhombic space group Pn2/sub 1/a with lattice parameters at 110 K of a = 18.502(9), b = 10.096(5), and c = 8.763(4)A. The molecule consists of a triangular array of Os atoms with one nonbridged edge (Os-Os = 2,855(3)A), one edge bridged by a single hydride (Os-Os = 3.053(3)A), and a third edge doubly bridged by a hydride atom and a methylene ligand (Os-Os = 2,824(3)A). The complex contains no terminal hydride ligands. The methylene carbon atom has a distorted tetrahedral geometry with an Os-C-Os angle of 82.1(1)/sup 0/ and a H-C-H angle of 106.0(8)/sup 0/.

Metal Complexes with Macrocyclic Ligands Part XXX†. Synthesis and structure of halocuprates of tetraprotonated 1,4,8,11-tetraazacyclotetradecane and its Cu2+ complex

Abstract: By mixing acidic solutions of 1,4,8,11-tetraazacyclotetradecane (Cy) with CuX2 (X = Cl−, Br−), either the hexahalocuprates of the tetraprotonated form of the macrocycle ([CyH4] [CuX6]) or the tetrahalocuprates of its Cu2+ complex ([CuCy] [CuX4]) are obtained. The structures of the chloro derivatives are established by X-ray diffraction analysis. In [CyH4] [CuCl6], the Cu2+ is in a tetragonally distorted octahedral geometry with four short and two long CuCl bonds. The tetraprotonated macrocycle is centrosymmetric, and its conformation is exodentate, so that the four ammonium groups are as far as possible from each other to minimize the electrostatic repulsion. In [CuCy] [CuCl4], the Cu2+ ion complexed by the macrocycle is surrounded by four N-atoms in a square-planar arrangement. In addition, the axial positions are occupied by two Cl− ions of two CuCl units, which act as bridges. The macrocycle is in the trans-III-configuration. The other Cu2+ ion is coordinated by four Cl− ions in a distorted tetrahedral geometry. IR and VIS spectra of the chloro and bromo derivatives are used to discuss the structure of the bromo species.