Constructor graph description of the hydrogen‐bonding supramolecular assembly in two ionic compounds: 2‐(pyrazol‐1‐yl)ethylammonium chloride and diaquadichloridobis(2‐hydroxyethylammonium)cobalt(II) dichloride

Covalent bond tables are used to generate hydrogen‐bond pattern designator symbols for the crystallographically characterized title compounds. 2‐(Pyrazol‐1‐yl)ethylammonium chloride, C₅H₁₀N₃⁺·Cl⁻, (I), has three unique, strong, charge‐assisted hydrogen bonds of the types N—H...Cl and N—H...N that form unary through ternary levels of graph‐set interactions. Diaquadichloridobis(2‐hydroxyethylammonium)cobalt(II) dichloride, [CoCl₂(C₂H₈NO)₂(H₂O)₂]Cl₂, (II), forms five unique charge‐assisted hydrogen bonds of the types O—H...Cl and N—H...Cl. These form graph‐set patterns up to the quinary level. The Co complex in (II) resides at a crystallographic inversion center; thus the number of hydrogen bonds to consider doubles due to their G‐equivalence, and the handling of such a case is demonstrated.     

4‐(3,5‐Dimethyl‐1H‐pyrazol‐4‐ylmethyl)‐3,5‐dimethyl‐1H‐pyrazol‐2‐ium dihydrogen phosphate: a combined X‐ray and DFT study

The molecular structure of the title salt, C₁₁H₁₇N₄⁺·H₂PO₄⁻, has been determined from single‐crystal X‐ray analysis and compared with the structure calculated by density functional theory (DFT) at the BLYP level. The crystal packing in the title compound is stabilized primarily by intermolecular N—H...O, O—H...N and O—H...O hydrogen bonds and π–π stacking interactions, and thus a three‐dimensional supramolecular honeycomb network consisting of R₄²(10), R₄⁴(14) and R₄⁴(24) ring motifs is established. The HOMO–LUMO energy gap (1.338 eV; HOMO is the highest occupied molecular orbital and LUMO is the lowest unoccupied molecular orbital) indicates a high chemical reactivity for the title compound.     

A novel dinuclear MoVI complex with tris(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methane

Recrystallization of [MoO₂Cl{HC(3,5‐Me₂pz)₃}]Cl [where HC(3,5‐Me₂pz)₃ is tris(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methane] led to the isolation of large quantities of the dinuclear complex dichlorido‐2κ²Cl‐μ‐oxido‐κ²O:O‐tetraoxido‐1κ²O,2κ²O‐[tris(3,5‐dimethyl‐1H‐pyrazol‐1‐yl‐1κN²)methane]dimolybdenum(IV) acetonitrile monosolvate, [Mo₂Cl₂O₄(C₁₆H₂₂N₆)]·CH₃CN or [{MoO₂Cl₂}(μ₂‐O){MoO₂[HC(3,5‐Me₂pz)₃]}]·CH₃CN. At 150 K, this complex cocrystallizes in the orthorhombic space group Pbcm with an acetonitrile molecule. The complex has mirror symmetry: only half of the complex constitutes the asymmetric unit and all the heavy elements (namely Mo and Cl) are located on the mirror plane. The acetonitrile molecule also lies on a mirror plane. The two crystallographically independent Mo⁶⁺ centres have drastically different coordination environments: while one Mo atom is hexacoordinated and chelated to HC(3,5‐Me₂pz)₃ (which occupies one face of the octahedron), the other Mo atom is instead pentacoordinated, having two chloride anions in the apical positions of the distorted trigonal bipyramid. This latter coordination mode of Mo^VI was found to be unprecedented. Individual complexes and solvent molecules are close‐packed in the solid state, mediated by various supramolecular contacts.     

4‐[Bis(1,5‐dimethyl‐1H‐pyrazol‐3‐yl­meth­yl)­amino]phenol monohydrate

The crystal structure of the title compound, C₁₈H₂₃N₅O·H₂O, shows mol­ecules containing a phenol group linked perpendicularly to a roughly planar fragment comprising two pyrazole rings. Mol­ecules are stacked perpendicular to the [101] direction, with their phenol groups disposed alternately. The mol­ecular packing in the crystal is stabilized by hydrogen bonding involving water mol­ecules.     

Dichloro­[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methane]zinc(II) and di‐μ‐chloro‐bis­{chloro­[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methane]cadmium(II)}

The Zn atom in dichloro­[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)­methane]zinc(II), [ZnCl₂(C₁₁H₁₆N₄)], (I), is tetra­hedrally coordinated by two N atoms from one bis­(3,5‐dimethyl­pyrazol­yl)methane ligand and two terminal Cl atoms. The mol­ecule has no crystallographic symmetry. One H atom of the CH₂ group of the bis­(3,5‐dimethyl­pyrazol­yl)methane ligand inter­acts with a Cl atom of an adjacent mol­ecule to yield inter­molecular C—H⋯Cl contacts, thereby forming a one‐dimensional zigzag chain extending along the b axis. On the other hand, in di‐μ‐chloro‐bis­{chloro­[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methane]cadmium(II)}, [Cd₂Cl₄(C₁₁H₁₆N₄)₂], (II), each of the two crystallographically equivalent Cd atoms is penta­coordinated by two N atoms from one bis­(3,5‐dimethyl­pyrazol­yl)methane ligand, and by one terminal and two bridging Cl⁻ anions. The mol­ecule has a crystallographic centre of symmetry located at the mid‐point of the Cd⋯Cd line. One H atom of the CH₂ group of the bis­(3,5‐dimethyl­pyrazolyl)­methane ligand inter­acts with a Cl atom of an adjacent mol­ecule to produce pairwise inter­molecular C—H⋯Cl contacts, thereby affording chains of mol­ecules running along the c axis.     

Constructor graph description of hydrogen bonding in a supra­molecular assembly of N,N′‐bis­(2‐hydr­oxy‐1‐methyl­ethyl)phthalamide

Hydrogen bonds of four types (N—H⋯O=C, N—H⋯OH, O—H⋯O=C and O—H⋯OH) connect mol­ecules of the title compound, C₁₄H₂₀N₂O₄, in the crystal into sheets folded into a zigzag pattern. The inter­molecular inter­actions are discussed in terms of the first‐ through fourth‐level graph sets, and a constructor graph helps visualize the supra­molecular assembly.     

Dihalodimethyltin(IV) complexes of 2‐(pyrazol‐1‐ylmethyl)pyridine

Reaction of dichloro‐ and dibromodimethyltin(IV) with 2‐(pyrazol‐1‐ylmethyl)pyridine (PMP) afforded [SnMe₂Cl₂(PMP)] and [SnMe₂Br₂(PMP)] respectively. The new complexes were characterized by elemental analysis and mass spectrometry and by IR, Raman and NMR (¹H, ¹³C) spectroscopies. Structural studies by X‐ray diffraction techniques show that the compounds consist of discrete units with the tin atom octahedrally coordinated to the carbon atoms of the two methyl groups in a trans disposition (Sn? C = 2.097(5), 2.120(5) Å and 2.110(6), 2.121(6) Å in the chloro and in the bromo compounds respectively), two cis halogen atoms (Sn? Cl = 2.4908(16), 2.5447(17) Å; Sn? Br = 2.6875(11), 2.7464(9) Å) and the two donor atoms of the ligand (Sn? N = 2.407(4), 2.471(4) Å and 2.360(5), 2.455(5) Å). In both cases, the Sn? N(pyridine) bond length is markedly longer than the Sn? N(pyrazole) distance. Copyright © 2003 John Wiley & Sons, Ltd.     

In situ synthesis of mononuclear copper(II) complexes of the new tridentate ligand bis[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methyl]amine

Two mononuclear copper complexes, {bis[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl‐κN²)methyl]amine‐κN}(3,5‐dimethyl‐1H‐pyrazole‐κN²)(perchlorato‐κO)copper(II) perchlorate, [Cu(ClO₄)(C₅H₈N₂)(C₁₂H₁₉N₅)]ClO₄, (I), and {bis[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl‐κN²)methyl]amine‐κN}bis(3,5‐dimethyl‐1H‐pyrazole‐κN²)copper(II) bis(hexafluoridophosphate), [Cu(C₅H₈N₂)₂(C₁₂H₁₉N₅)](PF₆)₂, (II), have been synthesized by the reactions of different copper salts with the tripodal ligand tris[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methyl]amine (TDPA) in acetone–water solutions at room temperature. Single‐crystal X‐ray diffraction analysis revealed that they contain the new tridentate ligand bis[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methyl]amine (BDPA), which cannot be obtained by normal organic reactions and has thus been captured in the solid state by in situ synthesis. The coordination of the Cu^II ion is distorted square pyramidal in (I) and distorted trigonal bipyramidal in (II). The new in situ generated tridentate BDPA ligand can act as a meridional or facial ligand during the process of coordination. The crystal structures of these two compounds are stabilized by classical hydrogen bonding as well as intricate nonclassical hydrogen‐bond interactions.     

Ethyl 3,5‐dimethyl‐4‐phenyl‐1H‐pyrrole‐2‐carboxylate

In the title compound, C₁₅H₁₇NO₂, the ethoxy­carbonyl group is anti with respect to the pyrrole N atom. The angle between the planes of the phenyl and pyrrole rings is 48.26 (9)°. The mol­ecules are joined into dimeric units by a strong hydrogen bonds between pyrrole N—H groups and carbonyl O atoms. The geometry of the isolated mol­ecule was studied by ab initio quantum mechanical calculations, employing both molecular orbital Hartree–Fock (MO–HF) and density functional theory (DFT) methods. The minimum energy was achieved for a conformation where the angle between the planes of the phenyl and pyrrole rings is larger, and that between the ethoxy­carbonyl and pyrrole planes is smaller than in the solid‐state mol­ecule.     

4‐(4‐Chloro­benzyl­ideneamino)‐1,5‐dimethyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐one and 4‐(2‐chloro­benzyl­idene­amino)‐1,5‐dimethyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐one

The two title compounds, both with formula C₁₈H₁₆ClN₃O, are structurally similar Schiff bases derived from the condensation of 4‐chloro­benzaldehyde or 2‐chloro­benzaldehyde with 4‐amino­anti­pyrine in methanol solution. As expected, both compounds adopt trans configurations about the central C=N bonds. In the crystal structure of the 4‐chloro analogue, mol­ecules are linked through weak C—H⋯O hydrogen bonds, forming chains running along the a axis. In the crystal structure of the 2‐chloro analogue, mol­ecules are linked through weak C—H⋯O and C—H⋯Cl hydrogen bonds, forming layers parallel to the ab plane.     

Synthesis of pinacol esters of 1‐alkyl‐1H‐pyrazol‐5‐yl‐ and 1‐alkyl‐1H‐pyrazol‐4‐ylboronic acids

Starting from 1H‐pyrazol, a wide number of 1‐alkyl‐1H‐pyrazol‐4‐yl and 1‐alkyl‐1H‐pyrazol‐5‐ylboronic acids and their pinacol esters were synthesized and characterized. The key step in the described methodology is the regioselective lithiation of the pyrazole ring. The synthesized pinacolates are stable under prolonged storage and can be used as convenient reagents in organic synthesis.     

4,4′‐Bi(1H‐pyrazol‐2‐ium) tetrachloridoaurate(III) chloride: a three‐dimensional cationic cooperite‐like framework with multiple pyrazolium–chloride hydrogen‐bonding interactions

In the title compound, (C₆H₈N₄)[AuCl₄]Cl, the 4,4′‐bi(1H‐pyrazol‐2‐ium) dication, denoted [H₂bpz]²⁺, is situated across a centre of inversion, the [AuCl₄]⁻ anion lies across a twofold axis passing through Cl—Au—Cl, and the Cl⁻ anion resides on a twofold axis. Conventional N—H...Cl hydrogen bonding [N...Cl = 3.109 (3) and 3.127 (3) Å, and N—H...Cl = 151 and 155°] between [H₂bpz]²⁺ cations (square‐planar node) and chloride anions (tetrahedral node), as complementary donors and acceptors of four hydrogen bonds, leads to a three‐dimensional binodal four‐connected framework with cooperite topology (three‐letter notation pts). The framework contains channels along the c axis housing one‐dimensional stacks of square‐planar [AuCl₄]⁻ anions [Au—Cl = 2.2895 (10)–2.2903 (16) Å; interanion Au...Cl contact = 3.489 (2) Å], which are excluded from primary hydrogen bonding with the [H₂bpz]²⁺ tectons.     

Azopyrazolobenzylidene derivatives of 4‐amino‐1,2,4‐triazol‐3‐ones. Synthesis of 4‐{[4‐(3,5‐dimethyl‐1H‐pyrazol‐4‐yl)diazenyl]‐benzylidene}amino‐2‐aryl‐5‐methyl‐3H‐[1,2,4]‐triazol‐3‐ones

The Schiff bases 3a‐h obtained from 4‐amino‐1,2,4‐triazol‐3‐ones 1a‐h when subjected to Japp‐Klingemann reaction yielded the corresponding 3‐{2‐[(2‐aryl‐5‐methyl‐3H‐[1,2,4]‐triazol‐3‐one‐4‐yl)]‐iminophenyl}‐pentane‐2,4‐diones 4a‐h . These diones on cyclisation with N₂H₄ yielded the title compounds 5a‐h . The energetics of the Keto‐enol tautomers of the diones was calculated by semiemperical calculations using AM1 and PM3 methods. All these compounds were screened for their antimicrobial activity against few microbes and most of them exhibited fungal inhibition more than the reference drugs used.     

[2,6‐Bis(3,5‐dimethylpyrazol‐1‐ylmethyl)pyridine]iodocopper(I) dichloromethane solvate

The title compound, [CuI(C₁₇H₂₁N₅)]·CH₂Cl₂, contains a tetracoordinate Cu^I centre with an unusual distorted tetrahedral stereochemistry, which has also been observed in other Cu^I complexes containing this tridentate ligand. This distortion is probably a result of intermolecular steric contacts between the I^? ligand and a neighbouring CH₂Cl₂ mol­ecule.     

Intramolecular hydrogen bonding in dichloridobis(3,5‐di‐tert‐butyl‐1H‐pyrazole‐κN2)cobalt(II) as a consequence of ligand steric bulk

The title compound, [CoCl₂(C₁₁H₂₀ClN₂)₂], forms two intramolecular hydrogen bonds [graph set S(5)] between the N atoms of the pyrazole ligands and the chloride ligands. This hydrogen‐bonding motif is uncommon among related compounds but occurs here because of the bulk of tert‐butyl substituents on the pyrazole ligands which shield the central metal atom to a significantly larger extent than pyrazole ligands with smaller 3,5‐substituents.     

Synthesis of 4‐amino‐3,5‐dinitro‐1H‐pyrazole using vicarious nucleophilic substitution of hydrogen

A novel synthesis of the title compound was achieved by direct animation using Vicarious Nucleophilic Substitution (VNS) methodology. Reaction of 1,1,1‐trimethylhydrazinium iodide with 3,5‐dinitropyrazole in DMSO produces 4‐amino‐3,5‐dinitro‐1H‐pyrazole as a 1:1 crystal solvate with DMSO. Recrystallization from water yields the monohydrated crystal. Recrystallization of the monohydrate from butyl acetate yields the compound in pure form.     

Carbonyl–carbonyl and carbonyl–π interactions as directing motifs in the supramolecular structure of carbonyl(3‐oxopenta‐1,4‐diene‐1,5‐diyl)[tris(3,5‐dimethyl‐1H‐pyrazol‐1‐yl‐κN2)methane]iridium(III) trifluoromethanesulfonate

In the title complex salt, [Ir(C₅H₄O)(C₁₆H₂₂N₆)(CO)](CF₃O₃S), the Ir^III centre adopts a distorted octahedral geometry with a facial coordination of the tris(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methane ligand. The C—C distances of the iridacycle are in agreement with its iridacyclohexa‐2,5‐dien‐4‐one nature, which presents a nonsymmetric boat‐like conformation with the C—Ir—C vertex more bent than the C—C(=O)—C vertex. The supramolecular architecture is mainly directed by CO...CO and CO...π and Csp³—H...O interactions, the arrangement of which depends on the anion.     

1‐Methyl‐1H‐imidazo[4,5‐f]quinolin‐6‐ium chloride monohydrate

The title compound, C₁₁H₁₀N₃⁺·Cl^?·H₂O, belongs to the N1‐methyl‐substituted imidazo­[4,5‐f]­quinoline family, in which the heterocyclic ring is protonated at the pyridine rather than at the imidazole N atom. The mol­ecule as a whole is almost exactly planar. The molecular structure has been compared with that of the 2‐amino analogue described in the literature, and it was found that the extra amino group of the latter is involved in conjugation with the adjacent double bond, i.e. the conjugation does not extend over the entire heterocyclic system. The cation of the title compound forms a strong hydrogen bond with the Cl^? anion and the anions are interconnected by the water solvent mol­ecule.