The intermolecular interactions in the aminonitromethylbenzenes

The intermolecular non-covalent interactions in aminonitromethylbenzenes namely 2-methyl-4-nitroaniline, 4-methyl-3-nitroaniline, 2-methyl-6-nitroaniline, 4-amino-2,6-dinitrotoluene, 2-methyl-5-nitroaniline, 4-methyl-2-nitroaniline, 2,3-dimethyl-6-nitroaniline, 4,5-dimethyl-2-nitroaniline and 2-methyl-3,5-dinitroaniline were studied by quantum mechanical calculations at RHF/311++G(3df,2p) and B3LYP/311++G(3df,2p) level of theory. The calculations prove that solely geometrical study of hydrogen bonding can be very misleading because not all short distances (classified as hydrogen bonds on the basis of interaction geometry) are bonding in character. For studied compounds interaction energy ranges from 0.23 kcal mol⁻¹ to 5.59 kcal mol⁻¹. The creation of intermolecular hydrogen bonds leads to charge redistribution in donors and acceptors. The Natural Bonding Orbitals analysis shows that hydrogen bonds are created by transfer of electron density from the lone pair orbitals of the H-bond acceptor to the antibonding molecular orbitals of the H-bond donor and Rydberg orbitals of the hydrogen atom. The stacking interactions are the interactions of delocalized molecular π-orbitals of the one molecule with delocalized antibonding molecular π-orbitals and the antibonding molecular σ-orbital created between the carbon atoms of the second aromatic ring and vice versa.      

Conformation of Sterically Hindered 4-Methyl-2-oxo-2-trityl-1,3,2-dioxaphosphorinane in the Solid State and the Solution

Abstract  

The cis- and trans-2-methyl-2-oxo-2-trityl-1,3,2-dioxaphosphorinanes were obtained in the Arbuzov reaction of 2-methoxy-4-methyl-1,3,2-dioxaphosphorinane with trityl chloride. The NMR spectra (¹H, ¹³C and ³¹P) in solution indicated that trans isomer exists in the form of two noncongruent molecules and it adopts two different conformations: a halfchair and a sofa, while the cis isomer exists as the mixed half/chair–sofa conformer. The compounds crystallise as a pure chiral forms and as a racemates. The solid state structural studies show that NMR data are consistent with the single crystal X-ray analysis, but the conformation existing in the crystal structure is more complex than it can be supposed on sole NMR determination. Crystal data: cis-isomer chiral form: space group P3₂, a = 8.782, b = 8.782, c = 21.680, α = 90.00, β = 90.00, γ = 120.00, V = 1448.0; cis-isomer racemate: space group Pca2₁, a = 16.773, b = 8.491, c = 27.006, α = 90.00, β = 90.00, γ = 90.00, V = 3846.2; trans-isomer racemate: space group Cc, a = 16.133, b = 8.388, c = 16.158, α = 90.00, β = 117.20, γ = 90.00, V = 1944.8; trans-isomer chiral form: space group P 1, a = 8.397, b = 9.003, c = 14.944, α = 80.76, β = 74.38, γ = 63.31, V = 971.1).     

The reactivity of [ReBr3(MeCN)(dppe)] towards gaseous nitric oxide. The X-ray structure of [ReBr3(MeCN)(dppe)] and [ReBr3(NO)(dppe)]0.57[ReOBr3(dppe)]0.43 and DFT calculations for [ReBr3(NO)(dppe)] and [ReOBr3(dppe)]

The [ReOBr₃(dppe)] (dppe=bis(diphenylophosphino)ethane) complex reacts with acetonitrile in the presence of excess of triphenylphpsphine to give a new monomeric nitrile rhenium(III) complex—[ReBr₃(MeCN)(dppe)] (1). The reaction of 1 with gaseous nitric oxide leads to the mixed [ReBr₃(NO)(dppe)]_0.57[ReOBr₃(dppe)]_0.43 complex (2) with rhenium atoms on +2 and +5 oxidation states. This paper presents the synthesis, spectroscopic characterisation and X-ray structure of 1 and 2. The geometries of [ReBr₃(NO)(dppe)] and [ReOBr₃(dppe)] have been optimized using the density functional theory (DFT) and the electronic transitions of [ReBr₃(NO)(dppe)] and [ReOBr₃(dppe)] have been calculated with the time-dependent DFT method (TDDFT). The UV–vis spectrum of 2 has been interpreted on the basis of the experimental data for [ReOBr₃(dppe)] and the calculated transitions for [ReOBr₃(dppe)] and [Re(NO)Br₃(dppe)].     

Synthesis, spectroscopic characterization, X-ray structure, and DFT calculations of [Cu(tppz)(SCN)2]

This article presents a combined experimental and computational study of [Cu(tppz)(SCN)₂], where ttpz stands for 2,3,5,6-tetra-(2-pyridyl)pyrazine. The compound has been studied by IR, UV–Vis spectroscopy, and single crystal X-ray analysis. The geometry around copper atom may be described as a distorted square pyramid. The equatorial plane is defined by three nitrogen atoms of tppz and one nitrogen atom of thiocyanate group. The apical site is occupied by nitrogen atom of the second SCN^? ion. The electronic spectrum of [Cu(tppz)(SCN)₂] was analyzed, and bands were assigned through the DFT/TDDFT procedures.     

The new arsine ruthenium(III) complex with pyrazole ligand

The [RuCl₃(AsPh₃)(C₃H₄N₂)₂] complex has been prepared and studied by IR, UV–VIS spectroscopy and X-ray crystallography. The complex was prepared in direct reaction of RuCl₃·H₂O with triphenylarsine and pyrazole in methanol. The electronic structure and UV–Vis spectrum of the obtained compound has been calculated using the TDDFT method.     

Heterobimetallic Cu(II)–Hg(II) polynuclear complexes containing Hg(SCN)42− unit – Synthesis,spectroscopic investigations,X-ray studies and magnetic properties

Three novel heterobimetallic polymers with Hg(SCN)₄^2? as a linker have been synthesised and characterized by means of IR, EPR, magnetic measurements and single crystal X-ray. All the obtained compounds [Cu(bpzm)Hg(SCN)₄]_n (1), [Cu(bdmpzm)Hg(SCN)₄]_n (2) and [Cu(dpa)Hg(SCN)₄]_n (3) form supramolecular framework structures. The 1 creates a three-dimensional coordination polymer, and 2 and 3 form two-dimensional nets extending along crystallographic (0 1 0) plane. Each octahedrally coordinated Cu(II) atom of 1 connects to four mercury ions through four thiocyanate bridges, and each Hg(II) ion is bridged with four copper ions via four thiocyanate bridges. The Cu(II) ions of 2 and 3 display a pyramidal coordination geometry, and they are connected to three mercury ions through three thiocyanate bridges, one thiocyanate ion is nonbridging group.     

Coordination chemistry of di-2-pyridylketone. Synthesis, spectroscopic investigations, X-ray studies and DFT calculations of Re(III) and Re(V) complexes

The paper presents a combined experimental and computational study of Re(III) and Re(V) complexes containing di-2-pyridylketone and its gem-diol form – [ReCl₃(dpk-N,O)(PPh₃)] (1), [ReCl₃(dpk-N,N′)(OPPh₃)] (2) and [ReOBr₃(dpk-OH)]·2(dpkH⁺Br⁻) (3). All the complexes have been characterized spectroscopically and structurally (by single-crystal X-ray diffraction). The complex 2 has been additionally studied by magnetic measurement. The magnetic behavior of 2 is characteristic of mononuclear octahedral Re(III) complex with d⁴ low-spin (³T_1g ground state) and arise because of the large spin–orbit coupling (ζ = 2500 cm⁻¹), which gives diamagnetic ground state. DFT and time-dependent (TD)DFT calculations have been carried out for [ReCl₃(dpk-N,N′)(OPPh₃)] and [ReOBr₃(dpk-OH), and their UV–vis spectra have been discussed on this basis.     

Synthesis,crystal, molecular,and electronic structure of [ReOCl3(bpzm)] complex

The [ReOCl₃(OAsPh₃)(AsPh₃)] and [ReOCl₃(PPh₃)₂] complexes react with bis(pyrazol-1-yl)methane (bpzm) to give [ReOCl₃(bpzm)]. The compound has been studied by IR, UV–Vis spectroscopy, and X-ray crystallography. The molecular orbital diagram of the oxocomplex has been calculated with the density functional theory (DFT) method. The spin-allowed singlet–singlet electronic transitions of [ReOCl₃(bpzm)] have been calculated with the time-dependent DFT method, and the UV–Vis spectrum of the title compound has been discussed on this basis.     

Oxorhenium complexes with the 8-quinolinolato ligand. X-ray structure and DFT calculations for [ReOX2(hqn)(AsPh3)] and [ReOX2(hqn)(PPh3)] complexes

The reactions of [ReOX₃(AsPh₃)₂] and [ReOX₃(PPh₃)₂] with 8-hydroxyquinoline (Hhqn) have been examined and the complexes [ReOX₂(hqn)(AsPh₃)] and [ReOX₂(hqn)(PPh₃)] (X = Cl, Br) have been obtained, respectively. The crystal and molecular structures of [ReOCl₂(hqn)(AsPh₃)] (1) and [ReOBr₂(hqn)(PPh₃)] (4) have been determined. The electronic structure of 1 has been calculated with the density functional theory (DFT) method. The spin-allowed electronic transitions of 1 have been calculated with the time-dependent DFT method, and the UV–Vis spectrum of [ReOCl₂(hqn)(AsPh₃)] has been discussed on this basis.