Showing papers on "Tetrahedral molecular geometry published in 2002"
TL;DR: One dimensional channels are formed in the three-dimensional open-framework iron selenite (I), which was synthesized hydrothermally from FeCl 3 ·6H 2 O, HF, and SeO 2 in the presence of the organic amine piperazine.
Abstract: One dimensional channels are formed in the three-dimensional open-framework iron selenite
[C 4 N 2 H 12 ] 0.5 [Fe 2 F 3 (SeO 3
) 2 ] (I), which was synthesized hydrothermally from FeCl 3 ·6H 2 O,
HF, and SeO 2 in the presence of the organic amine piperazine. The same inorganic
framework was also obtained with the amines diethylenetetramine, 1,3-diaminopropane, and
ethylenediamine. Compound I displays unusual magnetic frustration behavior that is attributed to the
tetrahedral geometry.
111 citations
TL;DR: The data for these complexes collectively suggest that the [PhBP(3)] ligand provides an unusually strong ligand-field to these divalent cobalt complexes that is chemically distinct from typical tris(phosphine) donor ligand sets, and distinct from tridentate borato ligands that have been previously studied.
Abstract: We have prepared a series of divalent cobalt(II) complexes supported by the [PhBP3] ligand ([PhBP3] = [PhB(CH2PPh2)3]-) to probe certain structural and electronic phenomena that arise from this strong field, anionic tris(phosphine) donor ligand. The solid-state structure of the complex [PhBP3]CoI (1), accompanied by SQUID, EPR, and optical data, indicates that it is a pseudotetrahedral cobalt(II) species with a doublet ground statethe first of its type. To our knowledge, all previous examples of 4-coordinate cobalt(II) complexes with doublet ground states have adopted square planar structure types. Complex 1 provided a useful precursor to the corresponding bromide and chloride complexes, {[PhBP3]Co(μ-Br)}2, (2), and {[PhBP3]Co(μ-Cl)}2, (3). These complexes were similarly characterized and shown to be dimeric in the solid-state. In solution, however, the monomeric low spin form of 2 and 3 dominates at 25 °C. There is spectroscopic evidence for a temperature-dependent monomer/dimer equilibrium in solution f...
104 citations
TL;DR: The distorted tetrahedral geometry of Zn3 was successfully reproduced at Cu1 in complex 3 and the cation structure of 1 and 2 closely resembles the trinuclear Zn(II) active site of P1 nuclease.
Abstract: New homo trinuclear Zn(II) complexes [Zn3L1(μ-OAc)](ClO4)2·3CHCl3·H2O, 1, and [Zn3L1(μ-OAc)]·ClO4·PF6·5CH3OH·H2O, 2, and hetero trinuclear complex [Zn2CuL1(μ-OAc)](ClO4)2·3CHCl3·H2O, 3, of optically active hexaaza triphenolic macrocycle H3L1 were synthesized and crystallographically characterized. The cation [Zn3L1(μ-OAc)]+ structure of 1 and 2 closely resembles the trinuclear Zn(II) active site of P1 nuclease. The distorted tetrahedral geometry of Zn3 was successfully reproduced at Cu1 in complex 3. The complexes 2 and 3 cleave CT DNA at 37 and 50 °C.
77 citations
TL;DR: In this article, the effect of side-chains on the subtle metal-ligand coding has been investigated in a self-assembly procedure for double helicate complexes, where the two bis-bidentate chelating units are separated by a single bond.
Abstract: Three new disilver(I) double helicate complexes [Ag2L2][ClO4]2
(1), [Ag2L2][BF4]2
(2)
[Ag2L2][NO3]2
(3) and a polymeric monohelical species [Ag2L′2][BF4]2
(4) have been generated via a self-assembly procedure to establish the effect of a side-chain on the subtle metal–ligand coding. The ligands, L = (C5H4N)C(CH3)N–NC(CH3)(C5H4N) and L′ = (C5H4N)CHN–NCH(C5H4N), were both readily prepared imine-based systems, in which the two bis-bidentate chelating units are separated by a single bond. Complexes 1, 2 and 3 adopt a double helical architecture, in which each silver centre is bound to two pyridylimine units in a distorted tetrahedral coordination geometry. Complex 4 is formed as an infinite monohelical polymer in which each silver centre is coordinated in a distorted tetrahedral geometry by two bidentate binding units from different ligands and the ligands are in turn coordinated to two silver(I) centres. While the two pyridylimine units of the ligand L are able to twist both in its free form and in the double helicates 1, 2 and 3, ligand L′ presents a planar conformation in both the free ligand and its monohelical complex 4. It is speculated that the arrangement of the two pyridylimine units around the N–N bond is essential to encode for a double helicate. Intra- and inter-molecular non-covalent interactions are found to stabilize the polymer 4 and provide opportunities for complexes 1, 2 and 3 to crystallize in different space groups.
55 citations
TL;DR: In this paper, the sulfur-bridged dinuclear copper (I) complex, [CuBr(η2-Sμ-C5H5NS)(p-Tol3P)]2 (1) was prepared by the reaction of insoluble CuBr2(C5h5NS)2 {from copper(II) bromide and pyridine-2-thione(c5H 5NS) in ethanol} with excess tri-p-tolylphosphine (pTol 3P) in
53 citations
TL;DR: NMR studies and UV-vis data for the cobalt complexes are consistent with a monomeric, four-coordinate geometry regardless of the nature of the solvent (i.e., donating (MeOH, CH(3)CN) vs nondonating (CH(2)Cl(2))) and are compared with other cobalt complex as well as cobalt-substituted His( 2)Cys metalloproteins.
Abstract: The new N2S(alkylthiolate) ligand 2-methyl-1-[methyl-(2-pyridin-2-ylethyl)amino]propane-2-thiolate, PATH (1), has been prepared and reacted with zinc(II) and cobalt(II) to give the monomeric complexes [(PATH)ZnBr] (2), [(PATH)ZnNCS] (3), [(PATH)CoBr] (4), and [(PATH)CoNCS] (5). The molecular structures of 4 and 5 have been determined by X-ray diffraction. Each complex displays a distorted tetrahedral geometry at the metal center, with the PATH ligand providing the N2S(alkylthiolate) donors. These complexes are close structural mimics of the active site of metalloproteins with a His2Cys−MII site such as that found in peptide deformylase. Complexes 4 and 5 are the first examples of crystallographically characterized CoII complexes with an N2SL (L ≠ N,S) donor set. Only one diastereomer for 2−5 is observed in the solid state, and simple molecular mechanics (Chem3D) calculations suggest this isomer is stable because of a favorable ligand conformation. NMR studies in the case of ZnII and UV−vis studies in the ...
53 citations
TL;DR: A series of new multidentate imine building blocks [NC5H4(R),CNCH2CH2NC(R)C5H 4N (R = H 1a, R = Me 1b)] have been synthesized, aiming at the formulation of extended coordination polymers with various transition metal ions.
Abstract: A series of new multidentate imine building blocks [NC5H4(R)CNCH2CH2NC(R)C5H4N (R = H 1a, R = Me 1b) and NC5H4CHN–NC(R)–C(R)N–NCHC5H4N (R = Ph 2a, R = Me 2b)] have been synthesized, aiming at the formulation of extended coordination polymers with various transition metal ions. Formation of the corresponding metal–ligand complexes has been monitored and characterized by chemical and spectroscopic techniques. X-Ray diffraction analysis of the available single crystals revealed diverse polymeric patterns of the hybrid organic–inorganic supramolecular systems. Complexation of Cu(I) with 1a and 2a yielded one-dimensional and two-dimensional polymers, respectively, with tetrahedral geometry around the metal centers. Similar reactions of Ag(I) with 1b and with 2a led to three-dimensional and two-dimensional arrays, respectively. The former contains silver ions with tetrahedral as well as square-planar coordination environments, while in the latter case the metal species bind to the ligands in a tetrahedral manner. Related syntheses of coordination compounds between 2a and bivalent metal ions produced 1-D polymers with Cd(II) and 2-D polymeric networks with Zn(II), Co(II) and Mn(II).
52 citations
TL;DR: Theoretical descriptions of the molecular nonlinear optical properties of tetrahedral donor-acceptor molecules were presented by using a valence-bond and four charge-transfer state model as discussed by the authors.
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.
46 citations
TL;DR: Four new mononuclear complexes with significant overlap between molecular magnetic orbitals leading to rather strong intermolecular antiferromagnetic interactions are synthesized and structurally and magnetically characterized.
Abstract: Four new mononuclear complexes of formula Cd(PN)(4)(NCS)(2) (A), Cd(PNN)(4)(N(3))(2) (B), Zn(PNN)(4)(N(3))(2) (C), and Zn(PNN)(2)(NCS)(2) (D), where PNN stands for 2-(4-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and PN for 2-(4-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl, were synthesized and structurally and magnetically characterized. The X-ray structures of compounds B and C were also determined at 90 K. Compounds A[bond]C crystallize in the triclinic space group P 1 macro (No. 2), and D crystallizes in the monoclinic space group P2(1)/m (No. 11). A[bond]C adopt a centrosymmetric distorted octahedral geometry in which the metal ions are bonded to four radical ligands through the nitrogen atom of the pyridyl rings and the azido or thiocyanato ligands occupy the apical positions. Compound D adopts a distorted tetrahedral geometry in which the zinc ion is bonded to two radicals and two thiocyanato ligands. As suggested by their magnetic behavior, the low-temperature X-ray structures of B and C show that these compounds undergo a clear structural change with respect to the room-temperature structures. The experimental magnetic behaviors were perfectly reproduced by a dimer model for A[bond]C and an alternating chain model for D while the sudden breaks observed in the chi(M)T versus T curves for B and C were well accounted for by the high- and low-temperature X-ray structures. For all these complexes the crystal structures favor significant overlap between molecular magnetic orbitals leading to rather strong intermolecular antiferromagnetic interactions.
41 citations
TL;DR: In this paper, an X-ray study reveals a dinuclear arrangement based on a planar LiNCaN four-membered ring: both metals engage in additional H3C...M (where M = Lt. Ca) interactions with the mu-N(SiMe3)(2) substituents resulting in a distorted tetrahedral geometry at lithium and a distorted trigonal-bipyramidal geometry at calcium.
39 citations
TL;DR: In this article, the electronic and vibrational properties of amorphous titania−silica materials with crystalline titania-cristobalite (TS-1) were compared.
Abstract: Both amorphous and crystalline silica doped with Ti(IV) ions have properties ranging from selective chemical catalysis to useful thermal and optical characteristics. These properties are related to the distribution of titanium sites in the silica lattice. It has been proposed that the Ti(IV) isomorphically substitutes for Si in the lattice in an essentially tetrahedral geometry. In this study we compare the electronic and vibrational spectroscopic characteristics of a series of both dense and porous amorphous titania−silica materials with crystalline titania−silicalite (TS-1). All of the spectroscopic properties are referenced to titania−cristobalite, which contains titanium in a rigorous crystallographic environment that deviates only slightly from tetrahedral. It is found that the amorphous materials have spectroscopic properties that are extremely close to Ti-cristobalite while TS-1 deviates significantly.
TL;DR: In this paper, a single-crystal X-ray diffraction, IR and UV-Vis spectroscopy was performed on WOS3Cu3Pz3Cl.
TL;DR: In this article, two copper(I) complexes containing the [MS 4 ] 2− core (M=Mo or W) and anionic Bp′ ligands have been prepared from the reaction system consisting of (Et 4 N) 2 [MS4 ], CuCl and KBp′ in acetone; their IR, UV-Vis, 1 H and 13 C NMR spectra have been studied.
TL;DR: In this article, the structure and energy calculations of the zinc and cadmium complexes of the peptide his-cys in their various provable geometries have been carried out using density functional methods.
Abstract: Structure and energy calculations of the zinc and cadmium complexes of the peptide his–cys in their various provable geometries have been carried out using density functional methods (LSDA pBP DN ∗ ). It is shown that, for the same complex geometry, the zinc complexes are more stable than the cadmium complexes and that, for the octahedral and square planar complexes, the cis isomers are favored over the trans isomers. It was found that the hexa-coordinated zinc complex has a distorted octahedral geometry, which, through elongation of the two H 2 O–Zn bonds, tends to adopt a square planar geometry and finally evolve to the preferred tetrahedral geometry. On the other hand, the cadmium complexes tend to stay in the octahedral geometry. These results suggest that the substitution of Zn by Cd as a probe for NMR studies of the Zn coordination environment in metaloproteins should be used with caution.
TL;DR: In this article, the self-assembly of dipotassium salt of piperazine-1,4-bis(2-ethanesulfonic acid) (K2pesp) with AgNO3 in H2O/DMF gave rise to a novel three-dimensional sulphonate silver(I) complex, [Ag2(μ2-OH2)(pesp)]n (1).
Abstract: Self-assembly of dipotassium salt of piperazine-1,4-bis(2-ethanesulfonic acid) (K2pesp) with AgNO3 in H2O/DMF gave rise to a novel three-dimensional sulphonate silver(I) complex, [Ag2(μ2-OH2)(pesp)]n (1). Each silver(I) ion is coordinated by one nitrogen and two oxygen atoms from three pesp ligands and one oxygen atom from coordinated water molecule in a distorted tetrahedral geometry.
TL;DR: In this paper, eleven tris(2-methyl-2-phenylpropyl)tin as well as four methyl bis[(phenyldimethylsilyl)methyl]tin β-germatranylpropionates have been synthesized, and their structures were characterized by elemental analyses, IR, multinuclear (1H, 13C, 119Sn) NMR, Mossbauer, and MS spectroscopies.
Abstract: Eleven tris(2-methyl-2-phenylpropyl)tin as well as four methyl bis[(phenyldimethylsilyl)methyl]tin β-germatranylpropionates have been synthesized, and their structures were characterized by elemental analyses, IR, multinuclear (1H, 13C, 119Sn) NMR, Mossbauer, and MS spectroscopies. All the spectroscopic studies suggest a tetrahedral geometry for the bulky triorganotin carboxylates. The preliminary bioassays have shown that most of the compounds have good acaricidal activity. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:592–598, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10039
TL;DR: The results provide evidence for the low-energy threshold required to allow hypercoordinated phosphorus to alter coordination geometry.
Abstract: The phosphane (C 6 H 4 -2-CH 2 NMe 2 ) 3 P (1) upon recrystallization from various solvents yielded the structurally different forms 1A, 1C, 1B 1 , and 1B 2 . Phosphane oxide (C 6 H 4 -2-CH 2 NOMe 2 ) 3 PO (2) was obtained from 1 by oxidation with hydrogen peroxide. X-ray analysis provided molecular structures for 1A, 1B 1 , 1B 2 , and 2. Phosphanes 1A and 1B 1 have pseudohexacoordinate frameworks as a result of the formation of two P-N donor interactions, 1B 2 has a pseudoheptacoordinate geometry due to the presence of three P-N interactions, and 2 resides in a tetrahedral geometry. The presence of the flexible dimethylaminobenzyl group in 1A, 1C, 1B 1 , and 1B 2 is reasoned to be responsible for this variation in coordination geometry. Phosphane oxide 2 has very strong donor oxygen atoms from N-oxide groups but they are involved in competition with the presence of hydrogen bonding, which results in the lack of donor coordination. High-resolution 1 H, 1 3 C, and 3 1 P NMR measurements are also reported. The results provide evidence for the low-energy threshold required to allow hypercoordinated phosphorus to alter coordination geometry.
TL;DR: In this paper, the fluorescence from single molecules of a new class of tetrahedral oligo(phenylenevinylene) (OPV) molecules was investigated and it was shown that significant molecular motion about the central carbon results in fluctuations in the polarizability axis of the molecule.
TL;DR: A flexible oxophlorin macrocycle, which allows the location of labile hydrogen atoms alternatively at the pyrrole nitrogen, oxygen, or meso-carbon atoms, has been studied by density functional theory (DFT).
Abstract: A flexible oxophlorin macrocycle, which allows the location of labile hydrogen atoms alternatively at the pyrrole nitrogen, oxygen, or meso-carbon atoms, has been studied by density functional theory (DFT). DFT calculations were carried out on oxophlorin 1, 5-hydroxyporphyrin 2, and two isomers of oxophlorin 3 and 4 (the proton added at the tetrahedral C(15) or the C(10) meso-carbon, respectively). The oxophlorin-hydroxyporphyrin structural changes are appropriately reflected by the significant changes of the meso carbon-oxygen bond lengths, which are in the limits of typical C=O and C-O distances. The rearrangement that creates the iso-oxophlorin macrocycle 3 (4) results in near tetrahedral geometry around the C(15) (C(10)) carbon atom, with the C(14)-C(15) and C(15)-C(16) (C(9)-C(10) and C(10)-C(11)) bond lengths corresponding to a single C-C bond. 5-Hydroxyporphyrin 2 is aromatic and has a bond pattern resembling that of regular porphyrin. In 1, 3, and 4, a localization of single and double bonds was seen, which agrees with the nonaromatic nature of oxophlorin, or isooxophlorin. The relative stability decreases in the order: 2 (0) > 3 (4.85) > 1 (5.11) > 4 (10.04) > 3-cis (12.89) (the number in parentheses is the relative energy, in kcal mol-1). The energy difference between the NH-cis and NH-trans tautomers, which is 8.04 kcal mol-1 for 3, results from a destabilizing NH-NH cis-interaction. DFT calculations were performed on the oxophlorin dianion radical (OP.)2- and a series of metallooxophlorin radicals ([(OP.)LiI]-, [(OP.)ZnII], [(OP.)GaIII]+, and (OP.)GaIIIF, in order to assess their electronic structures. Typically, the largest atomic spin density was found at the C(10) (C(20)) and C(15) meso positions, with the spin density at C(15) being twice as large as that at C(10). The spin density at the C(5) atom is negligible. A large spin density was found at the O(5) oxygen atom. The amount of spin density at the meso positions decreased as the cationic charge increased. When considering the absolute values of the spin densities, the opposite trend was observed at the pyrrolic carbon atoms. The spin density at the nucleus (Fermi contact terms) has also been analyzed. The spin distributions of iron oxophlorins determined by NMR were attributed to an oxophlorin radical electronic structure. The calculated spin density maps accounted for the essential NMR spectroscopic features of important intermediates in the heme degradation process--iron oxophlorin complexes. The DFT calculations reproduced the following spectroscopic patterns: a) |delta H(15)|>|delta H(10)|>>|delta (beta-H)|, b) a sign alteration of the contact shifts for identical substituents located on the same pyrrole ring.
TL;DR: In this paper, the tetrahedral sheets contain continuous T-O linkages, where T is normally Si or Al, and the apical oxygen forms part of the adjacent octahedral sheet, with six coordinated cations surrounded by oxygens and hydroxyls.
Abstract: Clay minerals are an important group of naturally occurring minerals found in soils and sediments. They have a sheet-like structure and the order of the sheets as well as the sheet composition contributes to the properties of the clay mineral. The tetrahedral sheets contain continuous T-O linkages with tetrahedral geometry, where T is normally Si or Al [1]. The apical oxygen of each tetrahedron forms part of the adjacent octahedral sheet, with six coordinated cations surrounded by oxygens and hydroxyls. If the cation is trivalent (eg. Al
TL;DR: The crystal structures of the anhydrous and monohydrated (dabcoH2)CuCl4⋅nH2O salts (n = 0,1) have been determined and a comparison of their crystal structures has been reported as discussed by the authors.
Abstract: The crystal structures of the anhydrous and monohydrated (dabcoH2)CuCl4⋅nH2O salts (n = 0,1) have been determined and a comparison of their crystal structures has been reported. The anhydrous salt is monoclinic P21/c with a = 9.045(2) A, b = 6.9270(10) A, c = 18.767(4) A and β = 90.07(3)° with V = 1175.8(4) A3. The hydrated salt is also monoclinic P21/c with a = 9.266(2) A, b = 9.395(2) A, c = 14.386(3) A and β = 93.32(3)° with V = 1250.3(5) A3. The structures of the two salts are closely related. Both compounds contain isolated distorted (compressed) tetrahedral CuCl4
2− anions, diprotonated dabco cations, and in the case of the hydrated salt, lattice H2O molecules. In the anhydrous salt, each of the two N–H+ groups of the dabcoH2
2+ dications form bifurcated hydrogen bonds to chloride ions on adjacent CuCl4
2− anions along the c axis, thus forming chains running parallel to the c axis. In the hydrated salt, a water molecule is inserted into one of the pair of bifurcated hydrogen bonds, forming instead N–H ⋅ ⋅ ⋅ O–H ⋅ ⋅ ⋅ CuCl4
2− linkages. The chains thus formed are cross-linked by O–H ⋅ ⋅ ⋅ Cl hydrogen bonds between the chains. Because of this additional hydrogen bonding, the CuCl4
2− anions in the hydrated salt are distorted further from tetrahedral geometry.
TL;DR: In this article, single crystals of AlBr3 · NH3 and AlI3· NH3 sufficient in size for X-ray structure determinations were obtained by evaporation/sublimation of the respective compound from its melt.
Abstract: Single crystals of AlBr3 · NH3 and AlI3 · NH3 sufficient in size for X-ray structure determinations were obtained by evaporation/ sublimation of the respective compound from its melt. The ammoniates were synthesized by the reaction of the pure halide with NH3 at -78°C and following homogenization by slowly heating the reaction mixture up to the melting points of the ammoniates (124°C and 126°C, respectively). The X-ray structure determinations for both monoammoniates were successfully carried out for the heavy atom positions (no hydrogen atoms): AlBr3 · NH3: Pbca, Z = 16, a = 11.529 (5) A, b = 12.188 (2) A, c = 19.701 (4) A AlI3 · NH3: Pbca, Z = 8, a = 13.536 (5) A, b = 8.759 (2) A, c = 14.348 (4) A The structures contain tetrahedral molecules Al(NH3)X3 with X = Br, I. They are not isotypic. The main difference is given for the coordination of NH3 by X- from neighbouring molecules. In Al(NH3)Br3 one of the two crystallographically independent NH3 ligands has 6Br- and the other 7Br- as neighbours whereas in Al(NH)3I3 only 5I- surround the one kind of NH3.
TL;DR: Single crystals of germanium(IV) tetrachloride, GeCl(4), were grown at 193 K and have very well realised tetrahedral geometry.
Abstract: Single crystals of germanium(IV) tetrachloride, GeCl4, were grown at 193 K. In the crystal structure, the isolated molecules have very well realised tetrahedral geometry.
TL;DR: A simple kinetic method has been applied to measure the formation constants of aqueous copper(I) with fumaronitrile, dimethyl fumarate, and fumaric and maleic acids, and all the results are discussed in terms of the effect of substituents on the olefin on the beta(1) values.
Abstract: A simple kinetic method has been applied to measure the formation constants of aqueous copper(I) with fumaronitrile, dimethyl fumarate, and fumaric and maleic acids. At 0.14 M ionic strength, the values of beta(1) are (0.85 +/- 0.02) x 10(3), (6.1 +/- 0.1) x 10(3), (7.3 +/- 0.1) x 10(3), and (2.2 +/- 0.4) x 10(3) M(-1), respectively. The values for the last two olefins are compared to previous results. Values of beta(1) for hydrogen maleate and beta(2) for fumaronitrile also have been determined. A reanalysis of much earlier work has been done, and all the results are discussed in terms of the effect of substituents on the olefin on the beta(1) values. The structure of bis(fumaronitrile)copper(I) nitrate also is reported. The nitrile is N-coordinated to copper(I), which has a distorted tetrahedral geometry, while the overall structure consists of macrocyclic Cu(6)(fumaronitrile)(6) rings which extend in three dimensions.
TL;DR: In this paper, the crystal structure of o-methacryloylaminophenylarsonic acid (o-MAPHA), C10H12AsNO4, was solved using direct methods with a refined R1 = 0.0483.
Abstract: The title compound, o-methacryloylaminophenylarsonic acid (o-MAPHA), C10H12AsNO4, is a monomer used to obtain water-soluble polyelectrolytes. It was obtained from the condensation reaction of o-arsanilic acid and methacryloyl chloride. Crystallization from aqueous ethanol solution yielded colorless prismatic crystals, and one was used for X-ray analysis. The crystal structure was solved using direct methods with a refined R1 = 0.0483. The crystal structure belongs to the triclinic system, space group \(P\bar 1\), and the asymmetric unit comprises two molecules of the o-MAPHA acid and one water molecule. Both acid molecules are approximately planar and in both molecules the As atom presents common tetrahedral geometry with two long As–O bonds for hydroxyl groups and one short As–O bond for the oxo groups. The structure of o-arsanilic acid (o-ARSA), C6H8AsNO3, was also determinated using the same methods and compared with the o-arsanilic acid structure previously reported. The crystal structure of the o-arsanilic acid belongs to the monoclinic crystal system and to the P21 noncentrosymmetric space group with Z equals two.
TL;DR: In this article, the title complex, [CaZn2(C7H5O2)6(C10H14N2O)2], has a centrosymmetric mol-ecule containing a linear array of two zinc and one central calcium ions bridged by two sets of three unsymmetrical benzoate ligands.
Abstract: The title complex, [CaZn2(C7H5O2)6(C10H14N2O)2], has a centrosymmetric molecule containing a linear array of two zinc and one central calcium ions bridged by two sets of three unsymmetrical benzoate ligands. Zinc is additionally coordinated by a nitrogen-base ligand to give distorted tetrahedral geometry, while the coordination of calcium by six benzoate O atoms is close to regular octahedral.
TL;DR: The title compound (C8H8N4) as discussed by the authors consists of the benzo-diimidazolium cation and tetra-chloro-zincate anion.
Abstract: The title compound, (C8H8N4)[ZnCl4], consists of the benzodiimidazolium cation and tetrachlorozincate anion. As expected, the benzodiimidazolium is essentially planar, while the [ZnCl4]2− unit has a regular tetrahedral geometry; they have approximate C2h and Td symmetry, respectively. The hydrogen bonding formed by the chloride ligand with the HN moiety leads to an extended two-dimensional structure.
TL;DR: In this article, the U(VI) atom is coordinated by seven O atoms in a distorted pentagonal-bipyramidal geometry, while the sulfoxide moiety is in a tetrahedral geometry.
Abstract: In the title compound, [UO(2)(C(15)H(11)O(2))(2)(C(14)H(14)OS)], the U(VI) atom is coordinated by seven O atoms in a distorted pentagonal-bipyramidal geometry. Both diphenylpropane-1,3-dionate systems are nearly planar. The sulfoxide moiety is in a distorted tetrahedral geometry, while its two aromatic rings are nearly orthogonal to one another. The crystal packing is stabilized by two bifurcated hydrogen-bonding interactions involving both uranyl O atoms.
TL;DR: The wavelength and O(2) dependencies of the quantum yield of (CH(3))(3)SnI disappearance indicate that the photochemistry of the complex initiates from the ligand-to-metal charge-transfer (LMCT) state populated on absorption in each medium.
Abstract: (CH3)3SnI exists as individual tetrahedral molecules in hexane but reacts with the silanol moieties present on the surface of porous glass and with the hydroxyl group of ethanol and hexanol to form...
TL;DR: The molecular structure of bis(trichlorosilyl)tert-butylphosphine has been determined in the gas phase by electron diffraction (GED) and high level ab initio molecular-orbital calculations as mentioned in this paper.
Abstract: The molecular structure of bis(trichlorosilyl)tert-butylphosphine has been determined in the gas phase by electron diffraction (GED) and high level ab initio molecular-orbital calculations. The C1 global minimum on the potential energy surface could be reached by twisting all three groups in the same sense by 15–20° from the fully staggered Cs conformation, found to be a saddle point and 26.7 kJ mol−1 higher in energy at HF/6-31G*. Important structural parameters (ra) are: (distances) P–C 190.6(6), P–Si (mean) 221.0(5), C–C (mean) 156.5(6) and Si–Cl (mean) 203.2(1) pm; (bond angles) P–C–C (mean) 109.7(6), C–P–Si 105.0(7) and 104.5(7), Si–P–Si 99.9(6), and P–Si–Cl (mean) 111.2°; (dihedral angles) Si(7)–P–C–C 87.0(17), Si(8)–P–C–C 168.3(17), Cl(17)–Si–P–C 68.3(17) and Cl(18)–Si–P–C 80.0(10)°. Theoretical predictions at the MP2(fc)/6-31G* level were used to restrain some of the refining parameters using the SARACEN method. The angles at silicon and carbon (tert-butyl) were found to vary from 105.9(7) to 117.4(5)°, indicating that the three groups are greatly distorted from regular tetrahedral geometry. The axial and equatorial components of the tilts of these groups have been investigated and the tert-butyl group was found to tilt in the direction of the phosphorus lone pair with virtually no equatorial tilt. One SiCl3 group is tilted towards the tert-butyl group and one tilted away, both with axial and equatorial components. The structures of the related molecules PBut(SiH3)2 and PBut(SiH3)(SiCl3) have also been investigated by ab initio calculations and the distortions analysed in a similar manner to those of PBut(SiCl3)2.