scispace - formally typeset
Search or ask a question
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.


Papers
More filters
Journal ArticleDOI
TL;DR: The structure of the reinforced ligand dpb {3,7-bis(2-pyridylmethyl)-3, 7-diazabicyclo[3.1]nonane} with copper(II) perchlorate has been determined: space group Pbcn(no. 60), a= 8.904(2), b= 14.366(1), c= 17.402(2)A, Z= 4, R= 0.0538.
Abstract: The structure of the complex of the reinforced ligand dpb {3,7-bis(2-pyridylmethyl)-3,7-diazabicyclo[3.3.1]nonane} with copper(II) perchlorate has been determined: space group Pbcn(no. 60), a= 8.904(2), b= 14.366(1), c= 17.402(2)A, Z= 4, R= 0.0538. The Cu–N bond lengths to the saturated nitrogens are 2.002(4)A, and those to the aromatic nitrogens of dpb are 1.976(4)A. The co-ordination geometry around Cu is considerably distorted away from the usual square-planar arrangement found with four nitrogen donor atoms, towards tetrahedral geometry, with the trans N–Cu–N angles being 161.1(2)° instead of the expected 180°. Molecular mechanics calculations showed that the distortion arises because of van der Waals repulsion between that two co-ordinated pyridyl groups of the ligand, particularly the hydrogen atoms ortho to the nitrogen donors. These calculations are also used to support the idea that the much greater thermodynamic stability of the complexes of dpb with smaller metal ions than is found for complexes of analogous unreinforced ligands is due to the rigid bispidine-type bridge of dpb.

21 citations

Journal ArticleDOI
TL;DR: In this paper, the structures of GeO2-Na2O glasses with different Na2O contents have been simulated by molecular dynamics (MD) and were found to be in good agreement with the existing experimental results.
Abstract: The structures of GeO2–Na2O glasses with different Na2O contents, from 0–30 mol%, have been simulated by molecular dynamics (MD) and were found to be in good agreement with the existing experimental results. The Ge–O coordination number was found to increase initially with the addition of alkali oxide. The results indicate that this increase in coordination number was due to the conversion of some of the tetrahedral germanate units into 5-fold coordinated trigonal bipyramidal units. Further additions of alkali oxide, beyond the glass composition range where maxima (or minima) in certain physical properties are experimentally observed (∼18 mol% Na2O), led to the formation of non-bridging oxygen (NBO) atoms and to a decrease of the average Ge–O coordination number. The reconversion to tetrahedral geometry was found to be responsible for the observed decrease in Ge–O coordination. A simple scheme was used to analyse the populations of various structural entities present in the glass system. It is shown that the conversion of 4-fold to 5-fold coordinated units and their back-conversion, with increasing alkali oxide contents, are feasible and consistent.

21 citations

Journal ArticleDOI
TL;DR: The donor-acceptor complex (BeCl2(Ph2PCH2PPh2)2] (1·2CH2Cl2) was prepared from beryllium dichloride and bis(diphenylphosphanyl)methane in dichloromethane suspension to give colorless single crystals, which were characterized by X-ray diffraction, IR spectroscopy, and DFT calculations as mentioned in this paper.
Abstract: The donor-acceptor complex [BeCl2(Ph2PCH2PPh2)2] (1·2CH2Cl2) was prepared from beryllium dichloride and bis(diphenylphosphanyl)methane in dichloromethane suspension to give colorless single crystals, which were characterized by X-ray diffraction, IR spectroscopy, and DFT calculations. Compound 1·2CH2Cl2 crystallizes monoclinically in space group C2/c with four formula units per unit cell. Lattice dimensions at 193(2) K: a = 2339.5(2), b = 916.7(1), c = 2415.4(2) pm, β = 97.15(1)°, R1 = 0.0386. The structure of 1 consists of distorted tetrahedral molecules with site symmetry C2 and bond lengths Be–Cl of 196.8(2) pm and Be–P of 220.6(3) pm. Quantum chemical calculations at the RI-BP86/SV(P) level give a structure of 1, which is in very good agreement with the experimental one. The calculations predict that the bond dissociation energies of the first and second Ph2PCH2PPh2 ligand from 1 are De = 16.8 kcal·mol–1 and 24.3 kcal·mol–1, respectively.

21 citations

Journal ArticleDOI
TL;DR: A covalently linked B ODIPY-PO2-smaragdyrin dyad is designed and synthesized and efficient energy transfer from the BODIPY unit to the PO2- smaragDyrin unit is demonstrated.
Abstract: The aromatic PO2 complexes of meso-triaryl-25-oxasmaragdyrins were synthesized by treating the free base 25-oxasmaragdyrins with POCl3 in toluene/triethylamine at refluxing temperature. The complexes are stable and characterized by X-ray and different spectroscopic techniques. In these complexes, the phosphorus(V) ion was bound to two pyrrolic nitrogen atoms of the smaragdyrin macrocycle and two oxygen atoms in tetrahedral geometry. The X-ray structure revealed that the smaragdyrin macrocycle showed significant distortion upon insertion of a PO2 unit, and the phosphorus atom lies 1.339 A above the mean plane defined by three meso-carbon atoms of the macrocycle. These complexes absorb strongly in the visible region and are 2.5 times more strongly fluorescent than free base 25-oxasmaragdyrins. The smaragdyrin macrocycle becomes electron-deficient upon complexation with a PO2 unit because these complexes are easier to reduce but difficult to oxidize compared to free base smaragdyrins. We designed and synthes...

21 citations


Network Information
Related Topics (5)
Hydrogen bond
57.7K papers, 1.3M citations
82% related
Molecule
52.4K papers, 1.2M citations
81% related
Crystal structure
100.9K papers, 1.5M citations
80% related
Ligand
67.7K papers, 1.3M citations
80% related
Aryl
95.6K papers, 1.3M citations
76% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202314
202240
202143
202039
201939
201847