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.

Synthesis, properties and molecular structures of iron(III), cobalt(II), nickel(II), copper(II), copper(I) and zinc(II) complexes with N,N-bis(pyrazol-1-ylmethyl)benzylamine

Abstract: A newly prepared ligand, N,N-bis(pyrazol-1-ylmethyl)benzylamine (L) reacted with metal ions to form [FeLCl3], [NiL(NCS)2(MeOH)], [MLX2](M = CoII, CuII or ZnII, X = Cl–, Br– or NCS–) and [(CuLI)2]. The crystallographically determined structures of [CoLCl2] and [CoL(NCS)2] reveal the co-ordination sphere of cobalt(II) to be intermediate between distorted tetrahedral and trigonal bipyramidal. In [NiL(NCS)2(MeOH)] the co-ordination sphere of nickel(II) ion is distorted octahedral while that of copper(II) in [CuLCl2] is distorted square pyramidal. The complex [(CuLI)2] displays distorted tetrahedral geometry around copper(I), and [ZnLBr2] shows distorted tetrahedral geometry around zinc(II).

Nonlinear optical properties of tetrahedral donor-acceptor octupolar molecules: Effective five-state model approach

Abstract: Theoretical descriptions of the molecular nonlinear optical properties of tetrahedral donor–acceptor molecules are presented by using a valence-bond and four charge-transfer state model. Based on this five-state model, as the extent of the charge transfer from the peripheral donors (acceptors) to the central acceptor (donor) increases, the first hyperpolarizability monotonically increases. The theoretical predictions are confirmed by carrying out ab initio calculations of the first hyperpolarizabilities of three different series of tetrahedral molecules. The π-electron delocalization effect on the nonlinear optical property is elucidated by making a comparison of the first hyperpolarizability of the tetrahedral molecule with that of fictitious tetrahedrally assembled linear polyynes.

Quantitative Evaluation of d–π Interaction in Copper(i) Complexes and Control of Copper(i)–Dioxygen Reactivity

Abstract: Crystal structures of the copper(I) complexes 1(X), 2, and 3 of a series of tridentate ligands L1(X), L2, and L3, respectively (L1(X): p-substituted derivatives of N,N-bis[2-(2-pyridyl)ethyl]-2-phenylethylamine; X=H, Me, OMe, Cl, NO(2); L2: N,N-bis[2-(2-pyridyl)ethyl]-2-methyl-2-phenylethylamine; L3: N,N-bis[2-(2-pyridyl)ethyl]-2,2-diphenylethylamine) were solved to demonstrate that all the copper(I) complexes involve an eta(2) copper-arene interaction with the phenyl ring of the ligand sidearm. The Cu(I) ion in each complex has a distorted tetrahedral geometry consisting of the three nitrogen atoms (one tertiary amine nitrogen atom and two pyridine nitrogen atoms) and C(1)-C(2) of the phenyl ring of ligand sidearm, whereby the Cu-C distances of the copper-arene interaction significantly depend on the para substituents. The existence of the copper-arene interaction in a nonpolar organic solvent (CH(2)Cl(2)) was demonstrated by the observation of an intense MLCT band around 290 nm, and the magnitude of the interaction was evaluated by detailed analysis of the (1)H and (13)C NMR spectra and the redox potentials E(1/2) of the copper ion, as well as by means of the ligand-exchange reaction between the phenyl ring and CH(3)CN as an external ligand. The thermodynamic parameters DeltaH(o) and DeltaS(o) for the ligand-exchange reaction with CH(3)CN afforded a quantitative measure for the energy difference of the copper-arene interaction in the series of copper(I) complexes. Density functional studies indicated that the copper(I)-arene interaction mainly consists of the interaction between the d(z(2) ) orbital of Cu(I) and a pi orbital of the phenyl ring. The copper(I) complexes 1(X) reacted with O(2) at -80 degrees C in CH(2)Cl(2) to give the corresponding (micro-eta(2):eta(2)-peroxo)dicopper(II) complexes 4, the formation rates k(obs) of which were significantly retarded by stronger d-pi interaction, while complexes 2 and 3, which exhibit the strongest d-pi interaction showed significantly lower reactivity toward O(2) under the same experimental conditions. Thus, the d-pi interaction has been demonstrated for the first time to affect the copper(I)-dioxygen reactivity, and represents a new aspect of ligand effects in copper(I)-dioxygen chemistry.

Magnesium complexes containing biphenyl-based tridentate imino-phenolate ligands for ring-opening polymerization of rac-lactide and α-methyltrimethylene carbonate

Abstract: A series of racemic 2-[(2′-(dimethylamino)biphenyl-2-ylimino)methyl]-4-R2-6-R1-phenols (L1H–L4H) were reacted with {Mg[N(SiMe3)2]2}2 to provide four heteroleptic magnesium complexes (L1–4)MgN(SiMe3)2·(THF)n (1, R1 = tBu, R2 = Me, n = 1; 2, R1 = R2 = CMe2Ph, n = 0; 3, R1 = CPh3, R2 = tBu, n = 1; 4, R1 = Br, R2 = tBu, n = 0), which have been fully characterized. X-ray structural determination shows that complex 1 possesses a monomeric structure, but complex 4 is dimeric with C2-symmetry where the two metal centers are bridged by two phenolate oxygen atoms of the ligands. The coordination geometry around the magnesium center in these complexes can be best described as a distorted tetrahedral geometry. The heteroleptic complexes 1–4 efficiently initiate the ring-opening polymerization of rac-lactide and α-methyltrimethylene carbonate (α-MeTMC) and the polymerizations are better controlled in the presence of 2-propanol. In general, the introduction of a bulky ortho-substituent on the phenoxy unit results in increases of both the catalytic activity and the stereo- or regioselectivity of the corresponding magnesium complex. Microstructure analyses of the resulting PLAs revealed that Pr values range from 0.46 to 0.81, depending on the catalyst and the polymerization conditions. For racemic α-MeTMC, detailed analyses using 1H and 13C NMR spectroscopy indicated the preferential ring-opening of α-MeTMC at the most hindered oxygen–acyl bond (Xreg = 0.65–0.86).

Structure-Triggered High Quantum Yield Luminescence and Switchable Dielectric Properties in Manganese(II) Based Hybrid Compounds.

Abstract: Two new manganese(II) based organic-inorganic hybrid compounds, C11H21Cl3MnN2 (1) and C11H22Cl4MnN2 (2), with prominent photoluminescence and dielectric properties were synthesized by solvent modulation. Compound 1 with novel trigonal bipyramidal geometry exhibits bright red luminescence with a lifetime of 2.47 ms and high quantum yield of 35.8 %. Compound 2 with tetrahedral geometry displays intense long-lived (1.54 ms) green light emission with higher quantum yield of 92.3 %, accompanied by reversible solid-state phase transition at 170 K and a distinct switchable dielectric property. The better performance of 2 results from the structure, including a discrete organic cation moiety and inorganic metal anion framework, which gives the cations large freedom of motion.