Adduct Formation,B−H Activation and Ring Expansion at Room Temperature from Reactions of HBcat with NHCs

We report the reactions of catecholborane (HBcat; 1 ) with unsaturated and saturated NHCs as well as CAAC^Me. Mono‐NHC adducts of the type HBcat?NHC (NHC=nPr₂Im, iPr₂Im, iPr₂Im^Me, and Dipp₂Im) were obtained by stoichiometric reactions of HBcat with the unsaturated NHCs. The reaction of CAAC^Me with HBcat yielded the B?H activated product CAAC^Me(H)Bcat via insertion of the carbine‐carbon atom into the B?H bond. The saturated NHC Dipp₂SIm reacted in a 2:2 ratio yielding an NHC ring‐expanded product at room temperature forming a six‐membered ?B?C=N?C=C?N? ring via C?N bond cleavage and further migration of the hydrides from two HBcat molecules to the former carbene‐carbon atom.     

Sodium 2‐nitro­ethanaloximate forms a layered‐framework structure

In the title compound, [Na(C₂H₃N₂O₃)], the Na⁺ cation lies on a centre of inversion in space group P2₁/m and all the atoms of the anion lie on a mirror plane. Na is octahedrally coordinated by four O and two N atoms from six different anions and each anion is coordinated to six different Na⁺ cations, forming chains of confacial octahedra which link the anion layers. Within these layers, the individual anions are linked by both O—H?O and C—H?O hydrogen bonds.     

1,4,4‐Tri­methyl‐9‐phenyl‐8‐oxa‐9‐aza­bi­cyclo­[3.2.2]­non‐6‐en‐2‐one

The structure of the adduct of eucarvone with nitro­so­benzene, C₁₆H₁₉NO₂, is reported. The [3.2.2] bicyclic system corresponds to two seven‐membered rings in boat and distorted chair conformations and a six‐membered ring that adopts a distorted boat conformation. No conjugation is observed between the phenyl group and the N—O system. The packing is directed mainly by a C?O hydrogen bond, C—H?O‐(1 ? x, ?y, z) and by intermolecular C—H?π interactions.     

3′,4′‐Bis(4‐chloro­phenyl)­spiro­[chroman‐3,5′(4′H)‐isoxazol]‐4‐one

The title compound, C₂₃H₁₅Cl₂NO₃, crystallizes with two independent mol­ecules in the asymmetric unit. The chroman­one moiety consists of a benzene ring fused with a six‐membered heterocyclic ring which adopts a sofa conformation. The five‐membered spiro­isoxazoline ring is in an envelope conformation. The p‐chloro­phenyl rings bridged by the five‐membered ring are nearly perpendicular to each other. The chromanone moiety of one mol­ecule packs into the cavity formed by the p‐chloro­phenyl rings of a second mol­ecule through the formation of C—H?π interactions. The structure is stabilized by weak C—H?O, C—H?Cl and C—H?π interactions.     

N,N′‐Bis­[tris­(hydroxy­methyl)­methyl]­ethanedi­amide: six O—H⃛O hydrogen bonds generate only a two‐­dimensional structure

Molecules of the title compound, C₁₀H₂₀N₂O₈, adopt a conformation which is almost centrosymmetric. The mol­ecules are disordered over two sets of sites with an occupancy ratio of 0.94:0.06. In the major form, there are two intramolecular O—H?O hydrogen bonds [O?O 2.756 (4) and 2.765 (4) Å; O—H?O 144 and 146°], in which the two amidic O atoms act as acceptors. In addition, there are four intermolecular O—H?O hydrogen bonds [O?O 2.650 (3)–2.666 (3) Å; O—H?O 158–171°]; these link each mol­ecule to six others in a continuous sheet structure which contains five distinct ring motifs, two of the S(7) type, two of the R(10) type and one of the R(22) type.     

Synthesis,spectroscopic characterization,antimicrobial activity and crystal structure of silver and copper complexes of sulfamethazine

Silver(I) and copper(II) complexes of 4-amino-N-(4,6-dimethyl-2-pyrimidinyl) benzenesulfonamide (smz) have been synthesized and characterized by elemental analysis and infrared (IR), ¹H NMR, and UV–vis spectroscopy. [Ag(smz)(pyridine)] (1) crystallizes in monoclinic system with space group P2₁/c and Z = 4, while [Cu(smz)₂(pyridine)₂]·H₂O (2) crystallizes in triclinic system with space group P-1 and Z = 2. X-ray analysis revealed that silver in 1 is four-coordinate exhibiting distorted tetrahedral geometry, while copper in 2 is coordinated to six nitrogens leading to a highly distorted octahedral geometry. The molecular structures of both 1 and 2 are stabilized by N–H?O and C–H?π intermolecular and C–H?O intramolecular interactions. Water plays a significant role in crystal packing by forming strong N–H?O_water intramolecular as well as O_water–H?N intermolecular interactions in 2. The results of IR, UV–vis, ¹H NMR spectral data and thermal analysis for 1 and 2 suggest that the binding of silver and copper to the sulfonamidic nitrogen is in agreement with the crystal structure determination. Antimicrobial activities of silver (1) and copper (2) complexes of sulfamethazine are studied by the dilution method against Staphylococcus aureus and Escherichia coli strains.     

3,5‐Pyrazole­di­carboxyl­ic acid monohydrate

In the title compound, C₅H₄N₂O₄·H₂O, the 3,5‐pyrazoledicarboxylic acid (H₃pdc) molecules are joined into one‐dimensional chains by O—H?O and N—H?O hydrogen bonds, with distances of 2.671 (2) and 2.776 (2) Å, respectively. The one‐dimensional chains form a three‐dimensional structure via O—H?OW and OW—HW?N hydrogen bonds, with distances of 2.597 (3) and 2.780 (3) Å, respectively. In addition to the potential for forming open‐channel frameworks, access to the six coordination atoms of H₃pdc can be directly controlled by varying the pH of the reaction environment, allowing further control over the design and synthesis of novel coordination polymers using various metal centers.     

Wellenmechanische Absolutrechnungen an Molekülen und Atomsystemen mit der SCF?MO?LC(LCGO) Methode. VIII. Das System (Li2H)+

The (Li₂H)⁺ has been investigated ab initio in the linear configuration, with the H atom in the middle of the system, for five different distances R_LiH, taking all six electrons into account, using the Allgemeines Programmsystem/SCF? MO? LC(LCGO) Verfahren. A bond distance R_LiH of 3.14 a.u., a total energy of ?15.289 a.u., and an ionization energy of 15.1 eV were found. Comparing the results of SCF investigations, the formation energy of (Li₂H)⁺ from LiH and Li⁺ was computed to be 59.7 kcal/mole (2.58 eV). Using the energy curve near the minimum, a force constant for the symmetric vibration of k = 0.13777 × 10⁶ dyn/cm and a frequency ω = 577.9 cm^?1 were found.     

1H and 13C NMR study of α-acetylenic PIII and PIV derivatives. Signs and magnitudes of J(P?C) and J(P?H)

All J(P? H) and J(P? C) values, including signs, have been obtained in acetylenic and propynylic phosphorus derivatives, R₂P(X)? C?C? H and R₂P(X)? C?C? CH₃ (X ? oxygen, lone pair and R ? C₆H₅, N(CH₃)₂, OC₂H₅, N(C₆H₅)₂, Cl) from ¹H and ¹³C NMR spectra. In P^IV derivatives the following signs are obtained: ¹J(P? C)+, ²J(P? C)+, ³J(P? C)+, ³J(P? H)+, ⁴J(P? H)? . Linear relations are observed between ¹J(P? C), ²J(P? C) and ³J(P? C) versus ³J(P? H), indicating that these coupling constants are mainly dependent on the Fermi contact term, though the other terms of the Ramsey theory do not seem to be negligible for ¹J(P? C) and ²J(P? C). In P^III derivatives these signs are: ¹J(P? C)- and +, ²J(P? C)+, ³J(P? C)-, ³J(P? H)-, ⁴J(P? H)+. Only ³J(P? C) and ³J(P? H) reflect a small contribution of the Fermi contact term while in ¹J(P? C) and ²J(P? C) this contribution seems to be negligible relative to the orbital and/or spin dipolar coupling mechanisms.     

Hydro­gen bonds and C—H⋯O ­interactions in the enol tautomer of 4‐­(phenylsulfonyl)spiro­[cyclo­pentane‐1,9′‐[9H]­fluorene]‐2,3‐dione

The title compound, 2‐hydroxy‐1‐(phenyl­sulfonyl)­spiro­[cyclo­pentene‐4,9′‐[9H]­fluoren]‐3‐one, C₂₃H₁₆O₄S, crystallized in the centrosymmetric space group P2₁/n with one mol­ecule as the asymmetric unit. The hydroxyl‐H atom is ordered and participates in a single intramolecular hydrogen bond and in a single intermolecular hydrogen bond, in which the O_D—H distance is 0.90 (2), H?O_A is 2.34 (3), O_D?O_A is 2.987 (2) Å and O_D—H?O_A is 129 (2)°. The intermolecular hydrogen bond forms an R(12) cyclic dimer about a center of symmetry. There are six leading C—H?O interactions. Taken together, these interactions form a three‐dimensional network. Structural comparisons are made with tetrabenzodi­spiro­[4.0.4.3]­tridecatetraene.     

2‐Amino‐4,6‐bis(benzyloxy)‐5‐nitrosopyrimidine: chains built from three‐centre N—H⋯(N,O) and N—H⋯π(arene) hydrogen bonds

The molecules of the title compound, C₁₈H₁₆N₄O₃, exhibit a very polarized molecular–electronic structure. The mol­ecules are linked into chains by a combination of an asymmetric three‐centre N—H?(N,O) hydrogen bond [H?N 2.19, H?O 2.54, N?N 3.041 (4) and N?O 2.977 (4) Å, and N—H?N 168, N—H?O 112 and N?H?O 67°] and an N—H?π(arene) interaction [H?Cg 2.67 Å, N?Cg 3.496 (4) Å and N—H?Cg 163°; Cg is a benzyl ring centroid].     

Preparations,IR spectra and crystal structures of cyano-bridged bimetallic complexes of zinc(II) and cadmium(II) with tetracyanopalladate(II)

The novel heteronuclear compounds [Zn(hydet-en)₂Pd(CN)₄] (1) and [Cd(hydet-en)₂Pd(CN)₄] (2) {hydet-en: N-(2-hydroxyethyl-ethylenediamine)} have been synthesized and characterized by elemental analyses and IR spectra. The crystal structures of 1 and 2 have been determined by X-ray diffraction. Structural analysis shows that both compounds have shown a polymeric chain, in which the Zn(II)/Pd(II) and Cd(II)/Pd(II) centres are linked by two CN groups. Both zinc and cadmium atoms are six coordinate with two trans cyanide–nitrogen and four hydet-en N atoms in a distorted octahedron arrangement; the palladium atoms in 1 and 2 are four coordinate with four cyanide-C atoms in a square planar arrangement. The chains in both compounds are connected through weak interchain hydrogen bonds, N–H?···?O, N–H?···?N and O–H?···?N, thereby forming a three-dimensional network.     

9‐Cyano‐10‐methylacridinium hydrogen dinitrate

The title compound, C₁₅H₁₁N₂⁺·HN₂O₆^?, crystallizes in the monoclinic space group C2/c with four mol­ecules in the unit cell. The planar 9‐cyano‐10‐methyl­acridinium cations lie on crystallographic twofold axes and are arranged in layers, almost perpendicular to the ac plane, in such a way that neighbouring mol­ecules are positioned in a `head‐to‐tail' manner. These cations and the hydrogen dinitrate anions are linked through C—H?O interactions involving four of the six O atoms of the anion and the H atoms attached to the C atoms of the acridine moiety in ring positions 2 and 4. The H atom of the hydrogen dinitrate anion appears to be located on the centre of inversion relating two of the four O atoms engaged in the above‐mentioned C—H?O interactions. In this way, columns of either anions or cations running along the c axis are held in place by the network of C—H?O interactions, forming a relatively compact crystal lattice.     

17‐Oxo‐16‐(2‐pyridyl­methyl­ene)­androst‐5‐en‐3β‐ol monohydrate

The title compound, C₂₅H₃₁NO₂·H₂O, has the outer two six‐membered rings in chair conformations, while the central ring is in an 8β,9α‐half‐chair conformation. The five‐membered ring adopts a 13,14‐half‐chair conformation. The pyridyl­methyl­ene moiety has an E configuration with respect to the carbonyl group at position 17. The structure is stabilized by intermolecular O—H?N and O—H?O hydrogen bonds.     

Influence of the Homopolar Dihydrogen Bonding CH⋅⋅⋅HC on Coordination Geometry: Experimental and Theoretical Studies

The reaction of the N‐thiophosphorylated thiourea (HOCH₂)(Me)₂CNHC(S)NHP(S)(OiPr)₂ (HL), deprotonated by the thiophosphorylamide group, with NiCl₂ leads to green needles of the pseudotetrahedral complex [Ni(L‐1,5‐S,S′)₂] ? 0.5 (n‐C₆H₁₄) or pale green blocks of the trans square‐planar complex trans‐[Ni(L‐1,5‐S,S′)₂]. The former complex is stabilized by homopolar dihydrogen C?H???H?C interactions formed by n‐hexane solvent molecules with the [Ni(L‐1,5‐S,S′)₂] unit. Furthermore, the dispersion‐dominated C?H??? H?C interactions are, together with other noncovalent interactions (C?H???N, C?H???Ni, C?H???S), responsible for pseudotetrahedral coordination around the Ni^II center in [Ni(L ‐1,5‐S,S′)₂] ? 0.5 (n‐C₆H₁₄).     

16‐[3‐Methoxy‐4‐(2‐piperidin‐1‐yl­ethoxy)­benzyl­idene]‐17‐oxoandrost‐5‐en‐3β‐yl acetate monohydrate

The title compound, C₃₆H₄₉NO₅·H₂O, has the outer two six‐membered rings of the steroid nucleus in chair conformations. The central ring B of the steroid nucleus is in an 8β,9α‐half‐chair conformation, while ring D of the steroid adopts a slightly distorted 13β,14α‐half‐chair conformation. The piperidine ring is in a chair conformation. The methoxy­benzyl­idene moiety has an E configuration with respect to the carbonyl group at position 17. Intermolecular O—H?O and O—H?N hydrogen bonds link the steroid and water mol­ecules into chains which run parallel to the b axis.     

The first coordination compounds of OP[NC4H8O]3 phosphoric triamide ligand: structural study and Hirshfeld surface analysis of SnIV and MnII complexes

The first X-ray crystal structures of coordination compounds of OP[NC₄H₈O]₃ phosphoric triamide (L) are investigated in Cl₂(CH₃)₂Sn(trans-L)₂ (1) and [Mn(H₂O)₄(trans-L)₂]Cl₂·2H₂O (2) as models of molecular and salt complexes for Hirshfeld surface (HS)-based analysis. The crystal packing of 1 includes weak interactions, while in the salt complex 2, a 2-D aggregate, along the (001) plane, is mediated by normal O–H?Cl and O–H?O hydrogen bonds. In the Hirshfeld study, the crystal cohesions of 1 and 2 are recognized via H?H, O?H/H?O, and Cl?H/H?Cl contacts. Among these interactions, hydrogen bonds O–H?Cl occur in the salt structure of 2, as well as some weaker hydrogen interactions as C–H?O (1 and 2), C–H?Cl (1), and O–H?O (2). The full fingerprint plots have nearly symmetric shapes for two independent molecules of 1, while an asymmetric shape appears for the cationic component of 2. To extract more detailed information on close intermolecular contacts, the molecular surface of the previously reported structure L was also mapped. The structure 2 is the first monomeric octahedral Mn(II)–phosphoric triamide complex reported so far. Furthermore, the HS analysis of 2 is the first such study on a cation–anion complex structure including phosphoric triamide ligand.     

Rearrangements in Model Peptide‐Type Radicals via Intramolecular Hydrogen‐Atom Transfer

Intramolecular H‐atom transfer in model peptide‐type radicals was investigated with high‐level quantum‐chemistry calculations. Examination of 1,2‐, 1,3‐, 1,5‐, and 1,6[C ? N]‐H shifts, 1,4‐ and 1,7[C ? C]‐H shifts, and 1,4[N ? N]‐H shifts (Scheme 1), was carried out with a number of theoretical methods. In the first place, the performance of UB3‐LYP (with the 6‐31G(d), 6‐31G(2df,p), and 6‐311+G(d,p) basis sets) and UMP2 (with the 6‐31G(d) basis set) was assessed for the determination of radical geometries. We found that there is only a small basis‐set dependence for the UB3‐LYP structures, and geometries optimized with UB3‐LYP/6‐31G(d) are generally sufficient for use in conjunction with high‐level composite methods in the determination of improved H‐transfer thermochemistry. Methods assessed in this regard include the high‐level composite methods, G3(MP2)‐RAD, CBS‐QB3, and G3//B3‐LYP, as well as the density‐functional methods B3‐LYP, MPWB1K, and BMK in association with the 6‐31+G(d,p) and 6‐311++G(3df,3pd) basis sets. The high‐level methods give results that are close to one another, while the recently developed functionals MPWB1K and BMK provide cost‐effective alternatives. For the systems considered, the transformation of an N‐centered radical to a C‐centered radical is always exothermic (by 25 kJ ? mol^?1 or more), and this can lead to quite modest barrier heights of less than 60 kJ ? mol^?1 (specifically for 1,5[C ? N]‐H and 1,6[C ? N]‐H shifts). H‐Migration barriers appear to decrease as the ring size in the transition structure (TS) increases, with a lowering of the barrier being found, for example when moving from a rearrangement proceeding via a four‐membered‐ring TS (e.g., the 1,3[C ? N]‐H shift, CH₃? C(O)? NH^. → ^.CH₂? C(O)? NH₂) to a rearrangement proceeding via a six‐membered‐ring TS (e.g., the 1,5[C ? N]‐H shift, ^.NH? CH₂? C(O)? NH? CH₃ → NH₂? CH₂? C(O)? NH? CH₂^.).     

16‐(4‐Cyanobenzylidene)‐3β‐pyrrolidinoandrost‐5‐en‐17β‐ol monohydrate

In the title compound, C₃₁H₄₀N₂O·H₂O, the outer two six‐membered rings are in chair conformations, while the central ring is in an 8β,9α‐half‐chair conformation. The five‐membered ring adopts a 13β‐envelope conformation and the cyano­benzyl­idene moiety has an E configuration with respect to the hydroxyl group at position 17. The steroid nuclei are linked by intermolecular O—H?O and O—H?N hydrogen bonds to form a molecular network. The molecular packing has an interesting feature, with the steroids aligned parallel to the b axis, forming a closed loop through hydrogen bonds linked via water mol­ecules.