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.

A Terminal Iron(IV) Nitride Supported by a Super Bulky Guanidinate Ligand and Examination of Its Electronic Structure and Reactivity

Abstract: Utilizing the bulky guanidinate ligand [LAr*]− (LAr* = (Ar*N)2C-(R), Ar* = 2,6-bis-(diphenylmethyl)-4-tert-butylphenyl, R = NCtBu2) for kinetic stabilization, the synthesis of a rare terminal Fe-(IV) nitride complex is reported. UV irradiation of a pyridine solution of the Fe-(II) azide [LAr*]-Fe-(N-(py) (3-py) at 0 °C cleanly generates the Fe-(IV) nitride [LAr*]-FeN-(py) (1). The 15N NMR spectrum of the 115N (50% Fe≡15N) isotopomer shows a resonance at 1016 ppm (vs externally referenced CH3NO2 at 380 ppm), comparable to that known for other terminal iron nitrides. Notably, the computed structure of 1 reveals an iron center with distorted tetrahedral geometry, τ4 = 0.72, featuring a short Fe≡N bond (1.52 A). Inspection of the frontier orbital ordering of 1 shows a relatively small HOMO/LUMO gap with the LUMO comprised by Fe-(dxz,yz)-N-(px,y) π*-orbitals, a splitting that is manifested in the electronic absorption spectrum of 1 (λ = 610 nm, e = 1375 L·mol–1·cm–1; λ = 613 nm (calcd)). Complex 1 persists in ...

Hindered rotational energy levels of a tetrahedron in a trigonal crystalline field

Abstract: The energy levels for the motion of a rigid tetrahedral molecule in a tetrahedral crystal field have been computed by the method developed by King and Hornig. The symmetry group of the Hamiltonian is T× T, where T is the tetrahedral group of rotations about body‐fixed axes and T is the tetrahedral group of rotations about space‐fixed axes.

Structure and Chemical Ordering in Amorphous Silicon Carbide Alloys

Abstract: Simulations of amorphous silicon carbide alloys indicate that the amorphous network deviates from an ideal tetrahedral geometry due to the presence of threefold-coordinated carbon atoms. All samples exhibit a significant degree of chemical ordering, most of it arising from fourfold-coordinated carbon atoms. The results show that there is no phase separation and that hydrogenation might promote tetrahedral carbon coordination, as well as chemical ordering.

Tertiary phosphine adducts of manganese(II) dialkyls. Part 2. Synthesis, properties, and structures of monomeric complexes

Abstract: Monomeric tetrahedral manganese dialkyl tertiary phosphine complexes of stoicheiometry MnR2(PR′3)2 have been identified in solutions by electron spin resonance spectra and the alkyl complex Mn(CH2CMe2Ph)2(PMe3)2 isolated and structurally characterised by X-ray crystallography. The molecule has a severely distorted tetrahedral geometry with P–Mn–P and C–Mn–C angles of 96.2 and 137.9° respectively, which reflect the relative sizes of the two kinds of ligand. The Mn–C and Mn–P distances are 2.149(6) and 2.633(4)A respectively. Use of the chelating phosphine, 1,2-bis(dimethylphosphino)ethane (dmpe), has allowed the isolation of the tetrahedral monomers MnR2(dmpe)(R = CH2SiMe3, CH2CMe3, and CH2Ph). The chelate dialkyl o-xylylene, o-(CH2)2C6H4, gives an octahedral complex Mn[o-(CH2)2C6H4](dmpe)2 whose structure has also been determined by X-ray diffraction. In this molecule, all metal-ligand bond lengths are shorter than the corresponding bonds in Mn(CH2CMe2Ph)2(PMe3)2. This is consistent with a significant reduction in the MnII radius on adoption of the low-spin state observed. The Mn–C distances are 2.110(5) and 2.1 04(6)A, while the Mn–P distances of 2.230(3)(trans to P) and 2.298(3)A(trans to C) reflect the different trans-influence abilities of alkyls and phosphines. The X-band e.s.r. spectra of the monomeric complexes have been studied in detail and are discussed in terms of distorted tetrahedral high-spin MnII and octahedral low-spin MnII species.