Theoretical Studies on Intermolecular Hydrogen-bond Interactions between Hexamethylenetetramine and Nitric Acid

The structures of the complexes generated by hexamethylenetetramine and nitric acid have been fully optimized by B3LYP method at the 6-311＋＋G＊＊ and aug-cc-pVTZ levels. The intermolecular hydrogen-bonding interactions have been calculated by the B3LYP/6-311＋＋G＊＊, B3LYP/aug-cc-pVTZ, MP2（full）/6-311＋＋G＊＊ and CCSD（T）/6-311＋＋G＊＊ methods, respectively. The NBO （nature bond orbital）, AIM （atom in molecule）, temperature effect and solvation effect have been analyzed to reveal the origin of the interactions. The results indicate that the stable hydrogen-bonded complexes could be generated by hexamethylenetetramine and nitric acid. The interactions follow the order of （a）（e）（b）（c）（d）（f）（g）. The C–N bonds which are adjacent to the methylene involving the hydrogen bonds tend to break in the chemical reaction. Due to the exothermic process, low temperature is conducive to the formation of the composition, which tallies with the experimental result.

Synthesis and Crystal Structure of Trans-diaquabis(hexamethylenetetramine-N)bis(isothiocyanato)cobalt(Ⅱ) trans-tetraaquabis(isothiocyanato)cobalt(Ⅱ) dihydrate

The synthesis and crystal structure of [Co(NCS)2(hmt)2(H2- O)2]穂Co(NCS)2(H2O)4]?H2O (hmt = hexamethylenetetramine) are reported. The crystal belongs to triclinic, space group P with unit cell parameters: a = 7.917(1), b = 9.023(1), c = 12.877(1) ? ?= 94.21(1), = 96.68(1), ?= 115.42(1)? C16H40Co2N12O8S4, Mr = 774.7, V = 817.33 3, Z = 1, Dc = 1.574 g/cm3, F(000) = 402 and (MoK? = 1.328mm-1. The final values of R and wR are 0.0251 and 0.0598, respectively, for 2545 observed reflections with I > 2(I). Each Co atom is in an octahedral coordination environment, and the independent uncharged components [Co(NCS)2(hmt)2(H2O)2], [Co(NCS)2(H2O)4] and H2O are linked together by three kinds of hydrogen bonds (O(2)H贩種(3) and O(3)H贩種(2), O(1)H贩稯(4) and O(3)H贩稯(4), O(2)H贩稴(2) and O(4)H贩稴(1)) to form a three-dimensional supramolecular architecture.

Synthesis and Crystal Structure of a Nickel(Ⅱ) Complex [Ni(H_2btc)_2(hmta)_2(H_2O)] with 1,3,5- Benzenetricarboxylate and Hexamethylenetetramine

The title compound, Ni(H2btc)2(hmta)2(H2O) (C30H35N8NiO13), has been syn- thesized by the reaction of Ni(CH3COO)2?H2O, 1,3,5-benzenetricarboxylate and hexame-thylene- tetramine in DMF and characterized by X-ray single-crystal diffraction. It crystallizes in the orthor- hombic system, space group Pccn with a = 20.610(4), b = 12.246(2), c = 12.907(3) ?, V = 3257(1) ?3, Z = 4, Mr = 774.37, F(000) = 1612, Dc = 1.579 g/cm3 and μ(MoKα) = 0.677 mm?1. The structure was refined to the final R = 0.0476 and wR = 0.1115 for 3221 observed reflections (I > 2σ(I)). Ni(II) ion is penta-coordinated with two oxygen atoms of monodentate carboxylate groups from two 1,3,5- benzenetricarboxylates, two nitrogen atoms from two hexamethylenetetramines in the equatorial plane, and one water molecule in the axial position. The coordination geometry of Ni(II) can be described as a nearly ideal square-pyramid. Hydrogen bonds exist between the complex molecules, leading to a two-dimensional structure.

Butterfly and Nest-Shaped Tp*-W-Cu-S Cluster Monomers and Dimers with Hexamethylenetetramine as Ligand:Anion-Dependent Structures and Nonlinear Optical Properties

Main observation and conclusion The assembly of[Et4N][Tp*WS3](1)with CuX(Tp*=hydridotris(3,5-dimethylpyrazol-1-yl)borate;X=Cl,Br,andI)or[Cu(MeCN)][PF6]in the presence of tetratopic ligand hexamethylenetetramine(HMT)afforded an array of four cluster-based compounds,which are either neutral or anionic.These compounds include[Tp*WSzCu3Cl2(HMT)](2,monomer,neutral),[Tp*WSzCugBr2(HMT)](3,monomer,neutral),[Tp*WSzCu3l1 s(HMT)21(4,dimer,anionic),and[Tp*WSzCu2(HMT)]2(PFc)2(5,dimer,anionic).The size of the halogen is found to dictate the structures(2/3 versus 4),and the presence/absence of halogen also affects the utiliation of coordinate site of HMT(4 versus 5)by creating more available CuOite in the case of 5.The structures of 2-5 are also characterized using elemental analysis,Fourier-transform infrared(FT-IR)spectra,and ultraviolet-visible(UV-Vis)spectroscopy,with the dimeric structure of 5 also selected for the third-order nonlinear optical(NLO)property investigations.The NLO measurement results suggest that the hyperpola rizability value(v)of 5,reflecting its NLO properties as a neat material,features 2.12×10^(-30)esu,and it is comparable to other W/Cu/S clus-terbased molecular entities,rendering 5 a promising NLO-active material.

Structural, Optical and Photocatalytic Properties of Cu2+ Doped ZnO Nanorods with Using HMTA Solvent Prepared by Hydrothermal Method

In this experiment, Cu2+ doped ZnO (Cu-ZnO) nanorods materials have been fabricated by hydrothermal method. Cu2+ ions were doped into ZnO with ratios of 2, 5 and 7 mol.% (compared to the mole’s number of Zn2+). The hexamethylenetetramine (HMTA) solvent used for the fabrication of Cu-ZnO nanorods with the mole ratio of Zn2+:HMTA = 1:4. The characteristics of the materials were analyzed by techniques, such as XRD, Raman shift, SEM and UV-vis diffuse reflectance spectra (DRS). The photocatalytic properties of the materials were investigated by the decomposition of the methylene blue (MB) dye solution under ultraviolet light. The results show that the size of Cu-ZnO nanorods was reduced when the Cu2+ doping ratio increased from 2 mol.% to 7 mol.%. The decomposition efficiency of the MB dye solution reached 92% - 97%, corresponding to the Cu2+ doping ratio changed from 2 - 7 mol.% (after 40 minutes of ultraviolet irradiation). The highest efficiency for the decomposition of the MB solution was obtained at a Cu2+ doping ratio of 2 mol.%.

MORPHOLOGY,INTERFACIAL INTERACTION AND PROPERTIES OF STYRENE-BUTADIENE RUBBER/MODIFIED HALLOYSITE NANOTUBE NANOCOMPOSITES

A natural nanotubular material,halloysite nanotubes(HNTs),was introduced to prepare styrene-butadiene rubber/modified halloysite nanotube(SBR/m-HNT) nanocomposites.Complex of resorcinol and hexamethylenetetramine (RH) was used as the interfacial modifier.The structure,morphology and mechanical properties of SBR/m-HNT nanocomposites,especially the interfacial interactions,were investigated.SEM and TEM observations showed that RH can not only facilitate the dispersion and orientation of HNTs in SBR matrix at ...

Synthesis and Crystal Structure of an Inclusion Compound Mn(SCN)_2(H_2O)_4·2C_6H_(12)N_4

A mononuclear manganese complex Mn(SCN)2(H2O)4?2C6H12N4 (C14H32O4N10MnS2, C6H12N4 = hexamethylenetetramine) has been synthesized. The molecular and crystal structures were determined by single-crystal X-ray diffraction. The crystal is of tetragonal, space group P42/mnm with a = 9.5591(7), b = 9.5591(7), c = 13.8253(15) ?, V = 1263.31(19) ?3, Z = 2, Mr = 523.56, Dc = 1.376 g/cm3, μ = 0.727 mm-1, F(000) = 550, Rint = 0.0302, T = 293(2) K, R = 0.0380 and wR = 0.1184 for 549 observed reflections with I > 2σ(I). In the crystal the manganese atom is six-coordinated by two nitrogen atoms from isothiocyanato anion and four oxygen atoms from water molecules, completing an octahedral geometry. Hexamethylenetetramine molecules are included in the lattice and connected to Mn(SCN)2(H2O)4 by hydrogen bonding and S…S interac- tions to form a three-dimensional supramolecular architecture.

Removing aluminum from a low-concentration lixivium of weathered crust elution-deposited rare earth ore with neutralizing hydrolysis

Aluminum,the main impurity in the lixivium of weathered crust elution deposited rare earth ore,not only results in an increasing consumption of precipitant in the rare earth precipitation process,but also lowers the purity of final rare earth product.Aluminum in the weathered crust elution-deposited rare earth ore lixivium should be removed.Neutralizing hydrolysis method was employed to remove aluminum from the lixivium.Hexamethylenetetramine was found to be the optimum pH regulator for the removal of aluminum in the low concentration.When used to adjust the pH value of the lixivium to 5.0,aluminum in the lixivium can be effectively removed in the form of aluminum hydroxide precipitation with removal rate of 97.60%.It shows that hexamethylenetetramine has a good effect on the removing of aluminum ions from the lowconcentration lixivium.Moreover,hexamethylenetetramine in removing aluminum from lixivium has little adverse effect on the RE precipitation process.

CRYSTAL STRUCTURE OF THE ADDUCT OF DECAVANADATE AND HEXAMETHYLENE-TETRAMINE {[HMT· H^+(V_(10)O_(28))^(6-)·H^+·HMT]· 2[HMT· CH_2NH_2]^+·2(H_3^+O)·12H^2O}

The title compound crystal belongs to the trilinic space group Ci1—P（?） with unit cell parameters: a=11.208 （4）, b=13.166 （4）, c=13.239 （3）,α=118.15 （2）°,β=94.78（2）°,γ=109.19 （2）°, and Z=1. The crystal structure was solved by direct method and difference Fourier techniques using the SHELXTL program, and was refined finally to R=RW=0.0462 for 4702 reflections. Structural analysis shows that the four protons in the cluster of the decavanadate group are separated into two types. For one of them, the two protons are captured by two O7 in the cluster of the decavanadate and two nitrogen atoms of the hexamethylenetetramine, to form hydrogen bonds; moreover, we have verified that the N-aminomethylhexamethylenetetraminium which was produced during the reaction existed in the title compound crystal. We infer that the N-aminomethylhexamethylenetetraminium [（CH2）6N4CH2NH2]+ could be produced by the heterogeneous catalysis reaction from the surface of the vanadium pentoxide [V2O5].

Synthesis, Structure and Characterization of a New Complex: [Mn(C_(6)H_(12)N_(4))_(2)(H_(2)O)_(4)][Mn(H_(2)O)_(6)][SO_(4)]_(2)·6H_(2)O

A novel complex,[Mn(C_(6)H_(12)N_(4))_(2)(H_(2)O)_(4)][Mn(H_(2)O)_(6)][SO_(4)]_(2)·6H_(2)O,was synthesized and hexagonal single crystals with centimeter-scale sizes were obtained by the method of solvent evaporation.It was characterized by elemental analysis,infrared spectrum,thermogravimetric analysis and X-ray single-crystal diffraction.The complex belongs to triclinic crystal system,space group PI with a=9.3390(8),b=13.3520(13),c=16.3207(13)?,α=100.7160(3)°,β=90.1020(10)°,γ=109.9490(5)°,V=1874.9(3)A^(3),Z=2,Dc=1.542 g/cm^(3),M_(r)=870.64,μ=0.876 mm^(-1),T=293(2) K,F(000)=916 and S=0.990.The crystal structure determination displayed a distorted octahedral geometry around the manganese atom,which is bound to two nitrogen atoms from hexamethylenetetramine,acting as monodentate ligands,and to four aqua ligands.Variable-temperature magnetic measurements of the complex indicate the presence of weak antiferromagnetic interaction between manganese centers.