共查询到20条相似文献,搜索用时 62 毫秒
1.
Dr. Shaoguang Zhang Dr. Peng Cui Tianchang Liu Qiuran Wang Thomas J. Longo Laura M. Thierer Dr. Brian C. Manor Dr. Michael R. Gau Dr. Patrick J. Carroll Prof. Dr. Georgia C. Papaefthymiou Prof. Dr. Neil C. Tomson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(35):15327-15331
Despite their connection to ammonia synthesis, little is known about the ability of iron-bound, bridging nitrides to form N−H bonds. Herein we report a linear diiron bridging nitride complex supported by a redox-active macrocycle. The unique ability of the ligand scaffold to adapt to the geometric preference of the bridging species was found to facilitate the formation of N−H bonds via proton-coupled electron transfer to generate a μ-amide product. The structurally analogous μ-silyl- and μ-borylamide complexes were shown to form from the net insertion of the nitride into the E−H bonds (E=B, Si). Protonation of the parent bridging amide produced ammonia in high yield, and treatment of the nitride with PhSH was found to liberate NH3 in high yield through a reaction that engages the redox-activity of the ligand during PCET. 相似文献
2.
E–H Bond Activation of Ammonia and Water by a Geometrically Constrained Phosphorus(III) Compound
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Dr. Thomas P. Robinson Daniel M. De Rosa Prof. Dr. Simon Aldridge Prof. Dr. Jose M. Goicoechea 《Angewandte Chemie (International ed. in English)》2015,54(46):13758-13763
The synthesis of a phosphorus(III) compound bearing a N,N‐bis(3,5‐di‐tert‐butyl‐2‐phenoxy)amide ligand is reported. This species has been found to react with ammonia and water, activating the E? H bonds in both substrates by formal oxidative addition to afford the corresponding phosphorus(V) compounds. In the case of water, both O? H bonds can be activated, splitting the molecule into its constituent elements. To our knowledge, this is the first example of a compound based on main group elements that sequentially activates water in this manner. 相似文献
3.
Amymarie K. Bartholomew Cristin E. Juda Jonathon N. Nessralla Benjamin Lin SuYin Grass Wang Yu‐Sheng Chen Theodore A. Betley 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5743-5747
The trichromium cluster (tbsL)Cr3(thf) ([tbsL]6?=[1,3,5‐C6H9(NC6H4‐o‐NSitBuMe2)3]6?) exhibits steric‐ and solvation‐controlled reactivity with organic azides to form three distinct products: reaction of (tbsL)Cr3(thf) with benzyl azide forms a symmetrized bridging imido complex (tbsL)Cr3(μ3‐NBn); reaction with mesityl azide in benzene affords a terminally bound imido complex (tbsL)Cr3(μ1‐NMes); whereas the reaction with mesityl azide in THF leads to terminal N‐atom excision from the azide to yield the nitride complex (tbsL)Cr3(μ3‐N). The reactivity of this complex demonstrates the ability of the cluster‐templating ligand to produce a well‐defined polynuclear transition metal cluster that can access distinct single‐site and cooperative reactivity controlled by either substrate steric demands or reaction media. 相似文献
4.
Peddy Vishweshwar Ashwini Nangia Vincent M. Lynch 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):1512-1514
In the crystal structure of the title diamide, C6H6N4O2, linear tapes of carboxamide N—H?O and pyrazine C—H?N hydrogen‐bond dimers are connected by N—H?O bonds to form a staircase‐like pattern. 相似文献
5.
Choudhury M. Zakaria George Ferguson Alan J. Lough Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(6):683-686
The title compound, [Ni2(C8H4O4)(C10H24N4)2(H2O)2](ClO4)2, contains two independent octahedral NiII centres with trans‐NiN4O2 chromophores. The bridging benzenedicarboxylate ligand is bonded to the two Ni atoms, each via one O atom of each carboxylate, while the other O atom participates in an intramolecular N—H?O hydrogen bond, forming an S(6) motif. The cations are linked to the perchlorate anions via O—H?O and N—H?O hydrogen bonds [O?O 2.904 (6) and 2.898 (6) Å; O—H?O 158 (6) and 165 (6)°; N?O 3.175 (7) and 3.116 (7) Å; N—H?O 168 and 166°] to form molecular ladders. These ladders are linked by further O—H?O and N—H?O hydrogen bonds [O?O 2.717 (6) and 2.730 (5) Å; O—H?O 170 (4) and 163 (6)°; N?O 3.373 (7) and 3.253 (7) Å; N—H?O 163 and 167°] to form a continuous three‐dimensional framework. The perchlorate anions both participate in three hydrogen bonds, and both are thus fully ordered. 相似文献
6.
Synthesis and Ligand Modification Chemistry of a Molybdenum Dinitrogen Complex: Redox and Chemical Activity of a Bis(imino)pyridine Ligand
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Grant W. Margulieux Zoë R. Turner Prof. Paul J. Chirik 《Angewandte Chemie (International ed. in English)》2014,53(51):14211-14215
The bis(imino)pyridine 2,6‐(2,6‐iPr2‐C6H3N?CPh)2‐C5H3N (iPrBPDI) molybdenum dinitrogen complex, [{(iPrBPDI)Mo(N2)}2(μ2,η1,η1‐N2)] has been prepared and contains both weakly (terminal) and modestly (bridging) activated N2 ligands. Addition of ammonia resulted in sequential N? H bond activations, thus forming bridging parent imido (μ‐NH) ligands with concomitant reduction of one of the imines of the supporting chelate. Using primary and secondary amines, model intermediates have been isolated that highlight the role of metal–ligand cooperativity in NH3 oxidation. 相似文献
7.
N. Jagadeesh Babu L. Sreenivas Reddy Srinivasulu Aitipamula Ashwini Nangia Prof. Dr. 《化学:亚洲杂志》2008,3(7):1122-1133
Crystal polymorphism in the antitumor drug temozolomide (TMZ), cocrystals of TMZ with 4,4′‐bipyridine‐N,N′‐dioxide (BPNO), and solid‐state stability were studied. Apart from a known X‐ray crystal structure of TMZ (form 1), two new crystalline modifications, forms 2 and 3, were obtained during attempted cocrystallization with carbamazepine and 3‐hydroxypyridine‐N‐oxide. Conformers A and B of the drug molecule are stabilized by intramolecular amide N? H???Nimidazole and N? H???Ntetrazine interactions. The stable conformer A is present in forms 1 and 2, whereas both conformers crystallized in form 3. Preparation of polymorphic cocrystals I and II (TMZ?BPNO 1:0.5 and 2:1) were optimized by using solution crystallization and grinding methods. The metastable nature of polymorph 2 and cocrystal II is ascribed to unused hydrogen‐bond donors/acceptors in the crystal structure. The intramolecularly bonded amide N–H donor in the less stable structure makes additional intermolecular bonds with the tetrazine C?O group and the imidazole N atom in stable polymorph 1 and cocrystal I, respectively. All available hydrogen‐bond donors and acceptors are used to make intermolecular hydrogen bonds in the stable crystalline form. Synthon polymorphism and crystal stability are discussed in terms of hydrogen‐bond reorganization. 相似文献
8.
George Ferguson Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):452-454
The title compound, N‐hydroxypropanamide, C3H7NO2, crystallizes with Z′ = 3 in P21/c. The molecules are linked by three N—H?O hydrogen bonds [N?O 2.8012 (16) to 2.8958 (15) Å; N—H?O 163 to 168°] and by three O—H?O hydrogen bonds [O?O 2.6589 (15) to 2.6775 (17) Å; O—H?O 165 to 177°] into a single three‐dimensional framework. 相似文献
9.
Gerhard Baum Alexander J. Blake Dieter Fenske Peter Hubberstey Carine Julio Matthew A. Withersby 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):m542-m544
Molecules of the title compound, [Cu(C2H3N)(C11H9N5)(C6H6N2O)](BF4)2·2C2H3N, comprise (acetonitrile)[2,6‐bis(pyrazol‐1‐yl)pyridine](isonicotinamide)copper(II) cations, tetrafluoroborate anions and lattice acetonitrile molecules. The cations have distorted square‐pyramidal geometries in which the N3‐donor, viz. 2,6‐bis(pyrazol‐1‐yl)pyridine, and the N‐donor, viz. the isonicotinamide ligand, occupy the four basal positions, with the coordinated acetonitrile N‐donor atom occupying the apical position. Pairs of cations are linked by N—H?F hydrogen bonds through tetrafluoroborate anions, forming centrosymmetric dimers, which are further linked by C—H?O hydrogen bonds into two‐dimensional undulating sheets, three of which interpenetrate to generate a two‐dimensional network. 相似文献
10.
《Journal of Coordination Chemistry》2012,65(3):257-264
A binuclear terbium(III) complex of N-(2-pyridinyl)ketoacetamide (HL) was synthesized and its crystal structure determined. Each terbium(III) binds to one N,O-bidentate HL, one O,O-bidentate L and two N,μ-O,O-tridentate bridging L ligands; the coordination polyhedron is a distorted square antiprism. The pyridine N and keto O atoms of the binucleating ligand are coordinated to each Tb with the amide O acting as a bridging atom. The adjacent [Tb2(HL)2L4]2+ units are bridged by double C(R)NH…ONO2…HN(R)C hydrogen bonds to form an infinite 1-D chain, and a 2-D layer structure results from a rare near face-to-face π,π-stacking interaction between the pyridine rings of the adjacent chains. The crystal structure analysis reveals that the ligands completely shield the Ln(III) ions. Excited by the absorption band at 370?nm, the Tb(III) complex displays characteristic metal-centered fluorescence while the ligand fluorescence is completely quenched, showing that efficient ligand-to-metal energy transfer (antenna effect) occurs. 相似文献
11.
Christian Nther Inke Jeß 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):m190-m192
The CuI cations in the title compound, [Cu(NCS)(C6H6N2O)2]n, are coordinated by N atoms from each of two mirror‐related nicotinamide ligands, as well as by one N atom of one thiocyanate ligand and one S atom of a symmetry‐related thiocyanate ligand, within a slightly distorted tetrahedron. The CuI cations and the thiocyanate anions are located on a crystallographic mirror plane and the nicotinamide ligands occupy general positions. The CuI cations are connected by the thiocyanate anions to form chains in the direction of the crystallographic a axis. These chains are connected by hydrogen bonds between the amide H atoms and the O atoms of adjacent nicotinamide ligands, to give a three‐dimensional structure. 相似文献
12.
Shyamaprosad Goswami Reshmi Mukherjee Kumaresh Ghosh Ibrahim Abdul Razak S. Shanmuga Sundara Raj Hoong‐Kun Fun 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):716-717
In the title compound, N‐(6‐chloro‐4‐oxo‐3,4‐dihydropteridin‐2‐yl)‐2,2‐dimethylpropanamide, C11H12ClN5O2, the rings in the pterin moiety are planar. The amide carbonyl O atom is in syn‐periplanar conformation while the C—N—C—C propanamide linkage is antiperiplanar. The N—H?N and N—H?O intermolecular hydrogen bonds transform the molecules into infinite chains. 相似文献
13.
《Journal of Coordination Chemistry》2012,65(6):1104-1112
The reaction of (Bu4N)2[Mo6O19] with 8-aminoquinoline in the presence of DCC (N,N′-dicyclohexylcarbodiimide) afforded the cis-dioxo-Mo(VI) amide [MoO2(NHC9H6N)2], which was characterized by spectroscopy, mass spectrometry, 1H NMR, and single-crystal X-ray analysis. X-ray crystallography shows that the complex exhibits a distorted octahedral geometry with each oxo ligand trans to the quinolyl nitrogen and the amido ligands are bound to the metal in an N,N-chelating fashion. The molecules form zigzag chains via C–H?···?O hydrogen bonds and the chains are connected into networks through interchain N–H?···?O hydrogen bonds. 相似文献
14.
Zhong‐Lu You 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(9):m406-m408
The title complex, [Cu(C11H14BrN2O)(NCS)]n, is an interesting thiocyanate‐bridged polynuclear copper(II) compound, which crystallizes with two independent molecules in the asymmetric unit. Each CuII atom is five‐coordinate in a square‐pyramidal configuration, with one O and two N atoms of one Schiff base ligand and one terminal N atom of a bridging thiocyanate ligand defining the basal plane, and one terminal S atom of another bridging thiocyanate ligand occupying the apical position. The {4‐bromo‐2‐[2‐(dimethylamino)ethyliminomethyl]phenolato}copper(II) units are linked by the bridging thiocyanate ligands, forming polymeric chains running along the a axis. There are weak intermolecular C—H⋯O and C—H⋯S hydrogen bonds between the chains in the crystal structure. 相似文献
15.
Muhammad Altaf Helen Stoeckli‐Evans 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(9):o441-o445
The title compounds, C10H9N5O·H2O (L1·H2O) and C16H12N6O (L2), were synthesized by solvent‐free aldol condensation at room temperature. L1, prepared by grinding picolinaldehyde with 2,3‐diamino‐3‐isocyanoacrylonitrile in a 1:1 molar ratio, crystallized as a monohydrate. L2 was prepared by grinding picolinaldehyde with 2,3‐diamino‐3‐isocyanoacrylonitrile in a 2:1 molar ratio. By varying the conditions of crystallization it was possible to obtain two polymorphs, viz. L2‐I and L2‐II; both crystallized in the monoclinic space group P21/c. They differ in the orientation of one pyridine ring with respect to the plane of the imidazole ring. In L2‐I, this ring is oriented towards and above the imidazole ring, while in L2‐II it is rotated away from and below the imidazole ring. In all three molecules, there is a short intramolecular N—H...N contact inherent to the planarity of the systems. In L1·H2O, this involves an amino H atom and the C=N N atom, while in L2 it involves an amino H atom and an imidazole N atom. In the crystal structure of L1·H2O, there are N—H...O and O—H...O intermolecular hydrogen bonds which link the molecules to form two‐dimensional networks which stack along [001]. These networks are further linked via intermolecular N—H...N(cyano) hydrogen bonds to form an extended three‐dimensional network. In the crystal structure of L2‐I, symmetry‐related molecules are linked via N—H...N hydrogen bonds, leading to the formation of dimers centred about inversion centres. These dimers are further linked via N—H...O hydrogen bonds involving the amide group, also centred about inversion centres, to form a one‐dimensional arrangement propagating in [100]. In the crystal structure of L2‐II, the presence of intermolecular N—H...O hydrogen bonds involving the amide group results in the formation of dimers centred about inversion centres. These are linked via N—H...N hydrogen bonds involving the second amide H atom and the cyano N atom, to form two‐dimensional networks in the bc plane. In L2‐I and L2‐II, C—H...π and π–π interactions are also present. 相似文献
16.
Waltraud Gamrad Angelika Dreier Dr. Richard Goddard Prof. Dr. Klaus‐Richard Pörschke 《Angewandte Chemie (International ed. in English)》2015,54(15):4482-4487
The pairing of ions of opposite charge is a fundamental principle in chemistry, and is widely applied in synthesis and catalysis. In contrast, cation–cation association remains an elusive concept, lacking in supporting experimental evidence. While studying the structure and properties of 4‐oxopiperidinium salts [OC5H8NH2]X for a series of anions X? of decreasing basicity, we observed a gradual self‐association of the cations, concluding in the formation of an isolated dicationic pair. In 4‐oxopiperidinium bis(trifluoromethylsulfonyl)amide, the cations are linked by N? H???O?C hydrogen bonds to form chains, flanked by hydrogen bonds to the anions. In the tetra(perfluoro‐tert‐butoxy)aluminate salt, the anions are fully separated from the cations, and the cations associate pairwise by N? C? H???O?C hydrogen bonds. The compounds represent the first genuine examples of self‐association of simple organic cations based merely on hydrogen bonding as evidenced by X‐ray structure analysis, and provide a paradigm for an extension of this class of compounds. 相似文献
17.
Jrg Schrder Herbert Wenzel Hans‐Georg Stammler Anja Stammler Beate Neumann Harald Tschesche 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):593-596
The title compounds, (2S)‐N‐[5‐(4‐chlorophenyl)‐2,3‐dihydro‐6H‐1,3,4‐thiadiazin‐2‐ylidene]‐2‐[(phenylsulfonyl)amino]propanamide, C18H17ClN4O3S2, (I), (2R)‐N‐[5‐(4‐fluorophenyl)‐6H‐1,3,4‐thiadiazin‐2‐yl]‐2‐[(phenylsulfonyl)amino]propanamide, C18H17FN4O3S2, (II), and (2S)‐N‐[5‐(5‐chloro‐2‐thienyl)‐6H‐1,3,4‐thiadiazin‐2‐yl]‐2‐[(phenylsulfonyl)amino]propanamide, C16H15ClN4O3S3, (III), are potent inhibitors of matrix metalloproteinases. In all three compounds, the thiadiazine ring adopts a screw‐boat conformation. The molecules of compound (I) show a short intramolecular NAla—H?Nexo hydrogen bond [N?N 2.661 (3) Å] and are linked into a chain along the c axis by Nendo—H?Sendo and Nendo—H?OAla hydrogen bonds [N?S 3.236 (3) and N?O 3.375 (3) Å] between neighbouring molecules. In compound (II), the molecules are connected antiparallel into a chain along the a axis by Nexo—H?OAla and NAla—H?Nendo hydrogen bonds [N?O 2.907 (6) and N?N 2.911 (6) Å]. The molecules of compound (III) are dimerized antiparallel through Nexo—H?Nendo hydrogen bonds [N?N 2.956 (7) and 2.983 (7) Å]. The different hydrogen‐bonding patterns can be explained by an amido–imino tautomerism (prototropic shift) shown by different bond lengths within the 6H‐1,3,4‐thiadiazine moiety. 相似文献
18.
John N. Low Antonio Quesada Antonio Marchal Manuel Melguizo Manuel Nogueras Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(5):o289-o294
Molecules of 2‐amino‐4,6‐dimethoxypyrimidine, C6H9N3O2, (I), are linked by two N—H?N hydrogen bonds [H?N 2.23 and 2.50 Å, N?N 3.106 (2) and 3.261 (2) Å, and N—H?N 171 and 145°] into a chain of fused rings, where alternate rings are generated by centres of inversion and twofold rotation axes. Adjacent chains are linked by aromatic π–π‐stacking interactions to form a three‐dimensional framework. In 2‐benzylamino‐4,6‐bis(benzyloxy)pyrimidine, C25H23N3O2, (II), the molecules are linked into centrosymmetric R(8) dimers by paired N—H?N hydrogen bonds [H?N 2.13 Å, N?N 2.997 (2) Å and N—H?N 170°]. Molecules of 2‐amino‐4,6‐bis(N‐pyrrolidino)pyrimidine, C12H19N5, (III), are linked by two N—H?N hydrogen bonds [H?N 2.34 and 2.38 Å, N?N 3.186 (2) and 3.254 (2) Å, and N—H?N 163 and 170°] into a chain of fused rings similar to that in (I). 相似文献
19.
John N. Low Paloma Arranz Justo Cobo M. Angeles Fontecha M. Luz Godino Rafael Lpez Debbie Cannon Antonio Quesada Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(6):680-682
In the title compound, [Ca(C9H11N6O5)2(H2O)3], the Ca atom lies on a twofold rotation axis in C2/c and the three water molecules are all disordered, each over two sites having equal occupancy. The anion acts as a bridging ligand between pairs of Ca sites on the same twofold axis, thus forming a one‐dimensional coordination polymer, with the chains lying along the twofold axes. These chains are linked by multiple O—H?O and N—H?O hydrogen bonds into a single three‐dimensional framework. 相似文献
20.
Ming‐Hua Yang 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(2):m59-m61
The title compound, poly[μ3‐bromido‐(pyridine‐3‐carboxylato‐κN)copper(I)], [CuBr(C6H5NO2)]n, is a novel coordination polymer based on a copper–bromide net and nicotinic acid ligands. The asymmetric unit contains one copper(I) ion, one bromide ligand and one nicotinic acid ligand, all on general positions. The CuI atom is tetrahedral and coordinated by three bridging Br atoms and the N atom from the nicotinic acid ligand. The Cu–Br units form alternating six‐membered chair‐patterned rings in net‐like layers. The attached nicotinic acid units point alternately up and down. The layers are assembled into a three‐dimensional network via intermolecular O—H...O and C—H...Br hydrogen‐bonding interactions. 相似文献