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.
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TL;DR: An analysis using Bader's Atoms in Molecules indicates that the Zn-N bonds are predominantly ionic with some covalent character and that there is a weak interaction between the metal and the hydroxyl groups.
Abstract: The crystal structure of the nitrate salt of N,N′-bis(2-hydroxyethyl)-ethane-1,2-diamine (BHEEN), and its complex with Zn(II) and Cd(II) are reported. (H2BHEEN)(NO3)2 packs in a layered structure with a herringbone pattern within each layer arising from H-bonding between amino and alcohol protons and NO3− counterions. In [Zn(BHEEN)2]Cl2, each ligand coordinates to Zn(II) through its two N-donors producing a distorted tetrahedral geometry at the metal centre. The two hydroxyethyl arms of each ligand are trans to each other and the crystals obtained contained a racemic mixture of the bis-trans-R,R and the bis-trans-S,S isomers. All four hydroxyl groups are H-bonded to chloride counter ions, creating a layered structure. Whilst distant from the metal ion (average 3.00 A), the four O atoms of the pendent hydroxylamino groups appear positioned to interact with the metal. The orientation of the arms is preserved in a B3LYP gas phase calculation of the structure. An analysis using Bader's Atoms in Molecules indicates that the Zn–N bonds are predominantly ionic with some covalent character and that there is a weak interaction between the metal and the hydroxyl groups. Several other weak interactions including four O⋯HN, five O⋯HC and a H–H dihydrogen bond were identified. The Cd(II) complex of BHEEN crystallised as a dimer [(μ-Cl)2(Cd(BHEEN)Cl)2)] with two asymmetrically-bound bridging Cl− ligands and a terminally-coordinated Cl− on each metal ion. One hydroxyl group of each ligand is coordinated to the metal and the uncoordinated hydroxyl group is H-bonded to the H atom of the coordinated hydroxyl group of the second ligand in the complex. The ESI-MS spectrum shows the presence of di-cadmium complexes, but the most intense peaks are due to mono-cadmium complexes. The gas phase B3LYP structure of the dimer energy-minimises into two monomers and the longer bond between Cd(II) and bridging Cl− breaks. Hence, dimerisation may be a consequence of the crystallisation process and the dimer may not be the predominant species in solution.
8 citations
TL;DR: The results suggest that the Nτ coordination of 4-MeIm ring to ZnII or CuII is more favorable whatever the level of calculation, and the addition of one water molecule in the first coordination sphere of the metal ions provides five-coordinated complexes showing no Nπ or Nτ preferences.
Abstract: A quantum chemistry study of mononuclear metal coordination with four 4-methylimidazole ligands (4-MeIm) was investigated. The four complexes [Cu(4-MeIm)4]2+, [Cu(4-MeIm)4, H2O]2+, [Zn(4-MeIm)4]2+ and [Zn(4-MeIm)4, H2O]2+ were studied with particular attention to the Nπ or Nτ possible coordinations of the 4-MeIm ring with the metals, using different DFT methods. The results suggest that the Nτ coordination of 4-MeIm ring to ZnII or CuII is more favorable whatever the level of calculation. In contrast, the addition of one water molecule in the first coordination sphere of the metal ions provides five-coordinated complexes showing no Nπ or Nτ preferences. There is good agreement between the DFT-calculated structure and those available experimentally. When metal ions are four-fold coordinated, they adopt a tetrahedral geometry. When CuII and ZnII are five-fold coordinated, highly symmetric structures or intermediate structures are calculated. Similar energies are calculated for different structures, suggesting flat potential energy surfaces. The addition of implicit solvent modifies the calculated first coordination sphere, especially for [Cu(4-MeIm)4, H2O]2+ structures. The QTAIM and ELF topological analyses of the interaction between CuII and the neutral ligands, clearly indicate a dative bonding with a strong ionic character.
8 citations
TL;DR: In this paper, the X-ray structure determination of the lead iodide adduct reveals an essentially tetrahedral lead(II) center, which is a rare coordination geometry for lead-II, which almost invariably is hemidirected, with a stereochemically active lone pair.
8 citations
TL;DR: In this paper, the authors presented the first pure host lattice clathrate with tetrahedral cavities. But the structure was not shown to be a double-shell structure, in which the first shell for the dianion M II X 4 2− is supplied by four tetrahedrally disposed crown ether molecules and the second by a diamond-like array of TlX 4 −.
8 citations
TL;DR: In this paper, the title ligand is coordinated in a bidentate fashion to the metal center via its both P=Se groups, consistent with a four-coordinate tetrahedral geometry for the cadmium center.
Abstract: Five new complexes ZnL2(ClO4)2 (1), CdL2(ClO4)2 (2), CdL2(BF4)2 (3), CdLCl2 (4), and CdL(NO3)2 (5) [L = ((Me2N)2PSe)2NMe] have been synthesized and characterized by elemental analysis, infrared (IR) and multinuclear (31P, 77Se, and 113Cd), and nuclear magnetic resonance (NMR) spectroscopy. The 31P and 77Se NMR data showed that the title ligand is coordinated in a bidentate fashion to the metal center via its both P=Se groups. The solution structure of the cadmium complexes was further confirmed by its 113Cd NMR spectra, which displayed a quintuplet for the perchlorate complex and a triplet for each of the nitrate and chloride complexes, respectively due to coupling with four (two ligands) and two (one ligand) equivalent phosphorus nuclei, consistent with a four-coordinate tetrahedral geometry for the cadmium center. The results are discussed and compared with the corresponding oxo and thio analogues.
8 citations