Three 1‐phenylindolin‐2‐one derivatives displaying different molecular dipole moments and different crystallographic symmetries

Three 1‐phenylindolin‐2‐one derivatives, namely 1‐phenylindolin‐2‐one, C₁₄H₁₁NO, (I), 5‐bromo‐1‐phenylindolin‐2‐one, C₁₄H₁₀BrNO, (II), and 5‐iodo‐1‐phenylindolin‐2‐one, C₁₄H₁₀INO, (III), have been synthesized and their structures determined. Compounds (I) and (II) crystallized in the centrosymmetric space groups Pbca and P2₁/c, respectively, while compound (III) crystallized in the polar space group Aea2. Density functional theory (DFT) calculations show that the molecular dipole moment gradually decreases in the order (I) > (II) > (III). The relatively smaller dipole moment of (III) and the larger non‐electrostatic intermolecular interactions may be the main reasons for the noncentrosymmetric and polar structure of (III).     

4,5‐Propyl­enedi­thio‐1,3‐di­thiole‐2‐thione and 4,5‐propyl­enedi­thio‐1,3‐di­thiol‐2‐one

4,5‐Propyl­ene­di­thio‐1,3‐di­thiole‐2‐thione, C₆H₆S₅, (I), crystallizes in the centrosymmetric space group P2₁/c. The molecular packing is characterized by pairs of S⋯S intermolecular contacts between neighbouring mol­ecules, which may account for the rather high thermal stablity of the crystal. 4,5‐Propyl­ene­di­thio‐1,3‐di­thiol‐2‐one, C₆H₆OS₄, (II), in which an O atom replaces the terminal S atom of (I), crystallizes in the non‐centrosymmetric polar space group Cc. The packing pattern of (II) indicates that the macropolarization direction is along [101]. Although the packing patterns are qualitatively significantly different, the molecular structures of (I) and (II) are similar, each exhibiting a chair conformation.     

An unusual methylene aziridine refined in P21/c and the nonstandard setting P21/n

The unusual methylene aziridine 6‐tert‐butyl‐3‐oxa‐2‐thia‐1‐azabicyclo[5.1.0]oct‐6‐ene 2,2‐dioxide, C₉H₁₅NO₃S, was found to crystallize with two molecules in the asymmetric unit. The structure was solved in both the approximately orthogonal and the oblique settings of space group No. 14, viz. P2₁/n and P2₁/c, respectively. A comparison of these results clearly displayed an increase in the correlation between coordinates in the ac plane for the oblique cell. The increase in the corresponding covariances makes a significant contribution to the standard uncertainties of derived parameters, e.g. bond lengths. Since there is yet no CIF definition for the full variance–covariance matrix, there are clear advantages to reporting the structure in the nonstandard space‐group setting.     

Two polymorphs,with Z′ = 1 and 2, of 2‐amino‐4‐chloro‐6‐morpholino­pyrimidine in P21/c,and 2‐amino‐4‐chloro‐6‐piperidino­pyrimidine,which is isomorphous and almost isostructural with the Z′ = 2 polymorph

Crystallization of 2‐amino‐4‐chloro‐6‐morpholino­pyrimidine, C₈H₁₁ClN₄O, (I), yields two polymorphs, both with space group P2₁/c, having Z′ = 1 (from diethyl ether solution) and Z′ = 2 (from di­chloro­methane solution), denoted (Ia) and (Ib), respectively. In polymorph (Ia), the mol­ecules are linked by an N—H⋯O and an N—H⋯N hydrogen bond into sheets built from alternating R(8) and R(40) rings. In polymorph (Ib), one mol­ecule acts as a triple acceptor of hydrogen bonds and the other acts as a single acceptor; one N—H⋯O and three N—H⋯N hydrogen bonds link the mol­ecules in a complex chain containing two types of R(8) and one type of R(18) ring. 2‐Amino‐4‐chloro‐6‐piperidino­pyrimidine, C₉H₁₃ClN₄, (II), which is isomorphous with polymorph (Ib), also has Z′ = 2 in P2₁/c, and the mol­ecules are linked by three N—­H⋯N hydrogen bonds into a centrosymmetric four‐mol­ecule aggregate containing three R(8) rings.     

Modulated Crystal Structure and Electronic Properties of Semiconductor Cu47Si91P144

Crystals of the copper silicon phosphide were synthesized by the iodine gas transport technique. The x‐ray single crystal methods revealed a big superstructure with the lattice parameters a = b = 44.510 and c = 20.772 Å and a basic tetragonal substructure with a = 3.7092 and c = 5.1930 Å. Analysis of the intensities showed that the superstructure has a ¹/₂,¹/₂,¹/₂ tetragonal substructure with a = 22.255 and c = 10.386 Å. This ¹/₂,¹/₂,¹/₂ substructure (Cu₄₇Si₉₁P₁₄₄) and the basic tetragonal structure (Cu_0.71Si_1.29P₂) were solved by the direct methods and refined in the I4m2 space group. The phosphide is a semiconductor with a small energy gap of 0.0269(1) eV. The electrical properties are considered in terms of Anderson localization. The density of states was calculated using the extended Hückel tight binding method.     

[1,2‐P2S8]2− – a New Member of the Thiophosphate Family: Synthesis,Crystal Structure and Vibrational Spectrum of [NH4(2.2.2‐cryptand)]2[1,2‐P2S8] and [NH4(18‐crown‐6)]2[1,2‐P2S8]·H2O

Colourless block‐shaped crystals of [(NH₄)₂(2.2.2‐cryptand)₂][P₂S₈] ( 1 ) and [(NH₄)₂(18‐crown‐6)₂][P₂S₈]·H₂O ( 2 ) could be obtained by the reaction of an aqueous solution of ammonium hexathiohypodiphosphate, (NH₄)₄P₂S₆·2 H₂O, with sulfur and 2.2.2‐cryptand or 18‐crown‐6. The crystal structures of both compounds have been determined by single‐crystal X‐Ray diffraction analysis. Compound 1 crystallizes in the monoclinic space group C2/c with a = 2032.7(2), b = 1243.6(2), c = 2244.6(2) pm, β = 98.64(1)°, and Z = 8, whereas compound 2 crystallizes also monoclinic in the space group P2₁/c with a = 2121.3(2), b = 865.5(1), c = 2345.4(2) pm, β = 91.96(1)°, and Z = 4. It could be established that the title compounds contain a new type of six‐membered [1,2‐P₂S₄] ring with P – P bond and three S – S linkages. The tetrahedral environment of each phosphorus is completed by a (formally) single and double bonded sulfur atom attached externally to the [1,2‐P₂S₄] ring. These terminal PS₂ units are mesomerically stabilized according to their P – S distances. FT‐IR and FT‐Raman spectra of the title compounds are recorded and interpreted.     

Synthesis,Structures, and Properties of Layered Quaternary Chalcogenides of the General Formula ALnEQ4 (A = K,Rb; Ln = Ce,Pr, Eu; E = Si,Ge; Q = S,Se)

Four related quaternary compounds containing rare‐earth metals have been synthesized employing the molten flux method and metathesis. The reactions of Eu and Rb₂S₅ with Si and Ge in evacuated fused silica ampoules at 725 °C for 150 h yielded RbEuSiS₄ ( I ) and RbEuGeS₄ ( II ), respectively. On the other hand, a reaction between CeCl₃ and K₄Ge₄Se₁₀ at 650 °C for 148 h has yielded KCeGeSe₄ ( III ) and KPrSiSe₄( IV ) was obtained by the reaction of elemental Pr, Si and Se in KCl flux at 850 °C for 168 h. Crystal data for these compounds are as follows: I , orthorhombic, space group P2₁2₁2₁ (#19), a = 6.392(1), b = 6.634(2), c = 17.001(3) Å, α = β = γ = 90°, Z = 4; II , monoclinic, space group P2₁/m (#11), a = 6.498(2), b = 6.689(3), c = 8.964(3) Å, β = 108.647(6)°, Z = 2; III , monoclinic, space group P2₁ (#4), a = 6.852(2), b = 7.025(2), c = 9.017(3) Å, β = 108.116(2)°, Z = 2; IV , monoclinic, space group P2₁ (#4), a = 6.736(2), b = 6.943(2), c = 8.990(1) Å, β = 108.262(2)°, Z = 2. The crystal structures of I ‐ IV contain two‐dimensional corrugated anionic layers of the general formula, [LnEQ₄]^? (Ln = Ce, Pr, Eu; E = Si, Ge and Q = S, Se) alternately piled upon layers of alkali cations. In addition to structural elucidation, Raman and UV‐visible spectroscopy, and magnetic measurements for compound III (KCeGeSe₄) are also discussed.     

3,4‐Lutidinium salts with the diiodidoaurate(I) anion: structure of [(3,4‐lut)2H]+·[AuI2]− and of two polymorphs of [(3,4‐lut)2H+]2·[AuI2]−·I−

Reactions between potassium tetraiodidoaurate(III) and pyridine (py, C₅H₅N) or 3,4‐lutidine (3,4‐dimethylpyridine, 3,4‐lut, C₇H₉N) were tested as possible sources of azaaromatic complexes of gold(III) iodide, but all identifiable products contained gold(I). The previously known structure dipyridinegold(I) diiodidoaurate(I), [Au(py)₂]⁺·[AuI₂]⁻, ( 3 ) [Adams et al. (1982). Z. Anorg. Allg. Chem. 485 , 81–91], was redetermined at 100 K. The reactions with 3,4‐lutidine gave three different types of crystal in small quantities. 3,4‐Dimethylpyridine–3,4‐dimethylpyridinium diiodidoaurate(I), [(3,4‐lut)₂H]⁺·[AuI₂]⁻, ( 1 ), consists of an [AuI₂]⁻ anion on a general position and two [(3,4‐lut)₂H]⁺ cations across twofold axes. Bis(3,4‐dimethylpyridine–3,4‐dimethylpyridinium) diiodidoaurate(I) iodide, [(3,4‐lut)₂H⁺]₂·[AuI₂]⁻·I⁻, ( 2 ), crystallizes as two polymorphs, each forming pseudosymmetric inversion twins, in the space groups P2₁ and Pc (but resembling P2₁/m and P2/c), respectively. These are essentially identical layer structures differing only in their stacking patterns and thus might be regarded as polytypes.     

Subcell and Superstructure of a High‐Temperature (β‐) Modification of the Mercury(I) Dimolybdate(VI) Hg2Mo2O7

A new (β‐)modification of the mercury molybdate Hg₂Mo₂O₇, thermodynamically stable at temperatures above 390 ± 10 °C, was prepared by solid state reaction of HgO with MoO₂ in sealed silica tubes. Its crystal structure, determined from single‐crystal X‐ray data, has a very pronounced subcell: space group P2/c, a = 600.9(1) pm, b = 388.7(1) pm, c = 1428.4(2) pm, β = 105.88(1)°, Z = 2, R = 0.052 for 797 structure factors and 52 variable parameters. In the superstructure of this high‐temperature β‐modification the a and the b axes of the subcell are doubled: C2/c, a = 1201.9(2) pm, b = 777.3(1) pm, c = 1428.4(2) pm, β = 105.88(1)°, Z = 8, R = 0.040 for 1490 F values and 110 variables. Like the previously reported low‐temperature α‐modification, the β‐modification consists of two‐dimensionally infinite sheets of edge‐ and corner‐sharing MoO₆ octahedra. These sheets are linked by Hg₂ pairs. Thus, the structures of the two modifications (α and β) differ essentially only in the orientation of the Hg₂ pairs, which are located between the sheets of the MoO₆ octahedra. The superstructure of the β‐modification differs from the subcell‐structure by the puckering of the sheets of MoO₆ octahedra. A hypothetical displacive phase transition between the subcell‐structure (corresponding to the potential high‐temperature structure) and the superstructure of β‐Hg₂Mo₂O₇ is discussed.     

The Reconstructive Phase Transformation β‐Co2P → α‐Co2P and the Structure of the High‐Temperature Phosphide β‐Co2P

Metallographical and differential thermoanalytical (DTA) investigatitons indicate that the well known phosphide Co₂P (Pearson code oP12, space group Pnma, Co₂Si type) is not stable up to the melting point, T = 1659 K; it is therefore designated as the low‐temperature phase α‐Co₂P. In the temperature range from 1428 to 1659 K, another, high‐temperature phase, designated as β‐Co₂P, exists. X‐ray powder diffraction investigation of liquid quenched alloys in the composition range x_P = 0.25 to 0.335, with x_P as the mole fraction, show that the high‐temperature phase β‐Co₂P is isotypic with Fe₂P (hP9, P 6 2m). For the ideal composition Co₂P, the unit cell parameters are: a = 5.742(2) Å, c = 3.457(5) Å, c/a = 0.621. Among the binary transition metal‐containing phosphides and arsenides isotypic with Fe₂P, β‐Co₂P is the only known high‐temperature phase and it shows (i) the highest axial ratio c/a and (ii) the “smallest” distortion of the hcp substructure formed by the transition metals atoms in the Fe₂P structure type.     

Three Crystal Structures,One Chemical Formula – Barium Dihydrogen‐hypodiphosphate(IV)‐dihydrate,BaH2P2O6·2H2O

Three polymorphs of barium dihydrogen‐hypodiphosphate(IV)‐dihydrate, BaH₂P₂O₆ · 2H₂O ( A , B and C ), were obtained and structurally characterized by single‐crystal X‐ray diffraction. A crystallizes in the monoclinic space group P2₁/n (no. 14) with a = 7.459(1) Å, b = 8.066(1) Å, c = 12.460(2) Å, β = 91.27(1) ° and Z = 4. B crystallizes in the monoclinic space group C2/c (no. 15) with a = 11.049(8) Å, b = 6.486(3) Å, c = 10.956(6) Å, β = 106.89(5) ° and Z = 4. C crystallizes in the orthorhombic space group C222₁ (no. 20) with a = 9.193(3) Å, b = 6.199(2) Å, c = 12.888(4) Å and Z = 4. Discrete [H₂P₂O₆]^2– units, barium cations and water molecules, held together by intermolecular hydrogen bonds of the type O–H ··· O, build up the structures of the three polymorphs. The phase purity of A and C was verified by powder diffraction measurements.     

Preparation and Crystal Structure Analyses of Compounds in the Systems HgO/MXO4/H2O (M = Co,Zn, Cd; X = S,Se)

During phase formation experiments under hydrothermal conditions (250 °C, 5d) in the systems HgO/MXO₄/H₂O (M = Co, Zn, Cd; X = S, Se), single crystals of the mercuric compounds (CdSO₄)₂(HgO)₂H₂O (I), (CdSeO₄)₂(HgO)₂H₂O (II), (CdSeO₄)Hg(OH)₂ (III), (CoSO₄)₂(HgO)₂H₂O (IV), (ZnSO₄)₂(HgO)₂H₂O (V), (ZnSeO₄)₂(HgO)₂H₂O (VI), and the mixed‐valent (ZnSe^IVO₃)(ZnSe^VIO₄)Hg^I₂(OH)₂ (VII) were obtained. The crystal structure determinations from X‐ray diffraction data revealed four unique structure types for these compounds. I and II crystallise isotypically in space group P2/n (a ≈ 7.85, b ≈ 6.28, c ≈ 10.5Å, β ≈ 102°), compound III crystallises in space group C2/m (a = 10.540(2), b = 9.0120(8), c = 6.1330(12)Å, β = 100.45(3)°), and the isotypic compounds IV, V and VI crystallise in space group Pbcm (a ≈ 6.15, b ≈ 11.3, c ≈ 13.1Å). Common with these three structure types are distorted octahedral [MO₆] and tetrahedral XO₄ building units which are organised in a layered assembly. Within the layers H bonding of OH groups or H₂O molecules of the [MO₆] octahedra leads to an additional stabilisation. Adjacent layers are separated by mercury atoms which are linearly bonded to two O atoms at short distances, forming either interconnecting [O‐Hg‐O] units which are part of [O‐Hg‐O]_∞ zig‐zag chains, or single [HO‐Hg‐OH] units (realised in compound III). VII is the only compound with mercury in oxidation state +1. It crystallises in space group C2/m (a = 17.342(3), b = 6.1939(10), c = 4.4713(8)Å, β = 90.154(3)°) and is made up of Hg₂²⁺ dumbbells, [ZnO₄(OH)₂] octahedra, and statistically distributed Se^VIO₄ and Se^IVO₃ groups as the main building units.     

Four N7‐benzyl‐substituted 4,5,6,7‐tetrahydro‐1H‐pyrazolo[3,4‐b]pyridine‐5‐spiro‐1′‐cyclohexane‐2′,6′‐diones as ethanol hemisolvates: similar molecular constitutions but different crystal structures

3‐tert‐Butyl‐7‐(4‐chlorobenzyl)‐4′,4′‐dimethyl‐1‐phenyl‐4,5,6,7‐tetrahydro‐1H‐pyrazolo[3,4‐b]pyridine‐5‐spiro‐1′‐cyclohexane‐2′,6′‐dione ethanol hemisolvate, C₃₀H₃₄ClN₃O₂·0.5C₂H₆O, (I), its 7‐(4‐bromobenzyl)‐ analogue, C₃₀H₃₄BrN₃O₂·0.5C₂H₆O, (II), and its 7‐(4‐methylbenzyl)‐ analogue, C₃₁H₃₇N₃O₂·0.5C₂H₆O, (III), are isomorphous, with the ethanol component disordered across a twofold rotation axis in the space group C2/c. In the corresponding 7‐[4‐(trifluoromethyl)benzyl]‐ compound, C₃₁H₃₄F₃N₃O₂·0.5C₂H₆O, (IV), the ethanol component is disordered across a centre of inversion in the space group P. In each of (I)–(IV), the reduced pyridine ring adopts a half‐chair conformation. The heterocyclic components in (I)–(III) are linked into centrosymmetric dimers by a single C—H...π interaction, with the half‐occupancy ethanol component linked to the dimer by a combination of C—H...O and O—H...π(arene) hydrogen bonds. The heterocyclic molecules in (IV) are linked into chains of centrosymmetric rings by C—H...O and C—H...π hydrogen bonds, again with the half‐occupancy ethanol component pendent from the chain. The significance of this study lies in the isomorphism of the related derivatives (I)–(III), in the stoichiometric hemisolvation by ethanol, where the disordered solvent molecule is linked to the heterocyclic component by a two‐point linkage, and in the differences between the crystal structures of (I)–(III) and that of (IV).     

Polymorphism in 2‐(4‐hydroxy‐2,6‐dimethylanilino)‐5,6‐dihydro‐4H‐1,3‐thiazin‐3‐ium chloride

Details of the structures of two conformational polymorphs of the title compound, C₁₂H₁₇N₂OS⁺·Cl⁻, are reported. In form (I) (space group P), the two N—H groups of the cation are in a trans conformation, while in form (II) (space group P2₁/c), they are in a cis arrangement. This results in different packing and hydrogen‐bond arrangements in the two forms, both of which have extended chains lying along the a direction. In form (I), these chains are composed of centrosymmetric R₄²(18) (N—H...Cl and O—H...Cl) hydrogen‐bonded rings and R₂²(18) (N—H...O) hydrogen‐bonded rings. In form (II), the chains are formed by centrosymmetric R₄²(18) (N—H...Cl and O—H...Cl) hydrogen‐bonded rings and by R₄²(12) (N—H...Cl) hydrogen‐bonded rings.     

Two New Modifications of [P(C6H5)4]2[Cu2I4]

Single crystals of two new modifications of [P(C₆H₅)₄]₂[Cu₂I₄] were obtained by reaction of granulated copper with iodine and [P(C₆H₅)₄]I in dry acetone under nitrogen atmosphere. They crystallise monoclinically, space group P2₁/n (No. 14), a = 11.550(6), b = 7.236(2), c = 27.232(13) Å, β = 98.13(3)°, V = 2253(2) ų, and Z = 2 ([P(C₆H₅)₄]₂[Cu₂I₄]-C), and space group Cc (No. 9), a = 17.133(5), b = 15.941(5), c = 18.762 (6) Å, β = 114.02(1)°, V = 4681(3) ų, and Z = 4 ([P(C₆H₅)₄]₂[Cu₂I₄]-D), respectively. In these compounds the [CuI₂]^? anions form dimers di-μ-iodo-diiodocuprate(I), which are either planar ( C ) or folded ( D ).     

Synthesis and Crystal Structure of Drum Organooxotin Clusters from Heteroaromatic Carboxylic Acid [PhCH2Sn（O）（O2CC5H4N）]6 and[PhCh2Sn）（O）（O2CC4H3O）]6

IntroductionRecentlywehaveinvestigatedthestructuralchemistryofanumberofdi ortri organotinheteroaromaticcarboxyl ates.1 5Thesestudieshaveshownthatthestructureoforgan otinheteroaromaticcarboxylatesisdependentonboththena tureofthealkylorarylsubstituentboundtothetinatomandthetypeofcarboxylateligand .Inparticular,majorstructuralvariationsareobservedwhencarboxylateligandcontainsanadditionaldonoratom ,suchasapyridineNatom ,availableforcoordinationtotheSnatom .1 3,5 8Wehavenowturnedtothemonoorganotin…     

Synthesis and Characterization of the first Copper(II) Complex of 6‐Azathymine. The Crystal Structure of [[CuCl2(H2O)2(AT)}2] · 2H2O; (AT = 6‐Azathymine)

The reaction of 3, 4‐dihydro‐6‐methyl‐3‐thioxo‐1, 2, 4‐triazin‐5(2H)‐one (6‐aza‐2‐thiothymine, AAT, 1 ) with copper(I) chloride in presence of hydrochloric acid in methanol gives the complex [{CuCl₂(H₂O)₂(AT)}₂] · 2H₂O, 2 , AT = 6‐azathymine) in excellent yield. 2 was characterized by IR spectroscopy and elemental analyses as well as mass spectrometry. Also single‐crystal X‐ray diffraction studies on compound 2 revealed that AT acts as a monodentate ligand in the centrosymmetric binuclear complex via its oxygen atom. Crystal data for 2 at —80 °C: space group P2₁/c with a = 550.1(1), b = 2712.5(1), c = 729.7(1) pm, β = 95.99(1)°, Z = 2, R₁ = 0.0213.     

Synthesis of the One-dimensional Compound (Ph4P)[In(P2Se6)] in a Ph4P+-Containing Selenophosphate Flux,and Structure of [In(P2Se6)2]5– – a Discrete Molecular Fragment of the [In(P2Se6)]nn– Chain

The reaction of one equivalent of In with a molten flux of (Ph₄P)₂Se₅ and P₂Se₅ (1 : 2), at 250 °C gave the (Ph₄P)[In(P₂Se₆)] ( I ). Stoichiometric elemental synthesis at 750 °C produced the Cs₅In(P₂Se₆)₂ ( II ). The thin, yellow crystals of ( I ), and the irregular, dark orange crystals of ( II ), appear to be air- and water-stable. Compound ( I ) crystallizes in the monoclinic space group C2/c (no. 15) and at 23 °C: a = 23.127(7) Å, b = 6.564(1) Å, c = 19.083(3) Å, β = 97.42(2)°, V = 2873(1) ų, Z = 4, final R/R_w = 4.4/5.2%. Compound ( II ) crystallizes in the tetragonal space group P4₂/m (no. 84) and at 23 °C: a = b = 13.886(1) Å, c = 7.597(2) Å, V = 1464.9(3) ų, Z = 2, final R/R_w = 3.9/5.1%. Compound ( I ) contains infinite [In(P₂Se₆)]_n^n– with a structure related to that of K₂FeP₂Se₆. Compound ( II ) contains the discrete [In(P₂Se₆)₂]^5– which can be viewed as a fragment of the [In(P₂Se₆)]_n^n– chain.     

Identification of a new family of phosphate compounds,AIBII6(P2O7)2P3O10: structures of KMn6(P2O7)2P3O10 and AgMn6(P2O7)2P3O10

Two members of a new family of inorganic phosphates of general formula A^IB^II₆(P₂O₇)₂P₃O₁₀; KMn₆(P₂O₇)₂P₃O₁₀ (a=5.405(2), b=26.918(11), c=6.660(5), β=107.31(3)°, V=925.1(9) Å³, space group P2₁/m, Z=2, D_calc=3.481 Mg m⁻³, R=0.0377 for 2235 observed reflections) and AgMn₆(P₂O₇)₂P₃O₁₀ (a=5.424(7), b=26.97(4), c=6.627(9), β=106.81(7)°, V=928(2) Å³, space group P2₁/m, Z=2, D_calc=3.716 Mg m⁻³, R=0.0594 for 1577 observed reflections) have been synthesized and identified by single crystal X-ray diffraction. The isostructural complexes present an interesting comparison of silver and potassium bonding.     

Seven 5‐benzylamino‐3‐tert‐butyl‐1‐phenyl‐1H‐pyrazoles: unexpected isomorphisms,and hydrogen‐bonded supramolecular structures in zero,one and two dimensions

5‐Benzylamino‐3‐tert‐butyl‐1‐phenyl‐1H‐pyrazole, C₂₀H₂₃N₃, (I), and its 5‐[4‐(trifluoromethyl)benzyl]‐, C₂₁H₂₂F₃N₃, (III), and 5‐(4‐bromobenzyl)‐, C₂₀H₂₂BrN₃, (V), analogues, are isomorphous in the space group C2/c, but not strictly isostructural; molecules of (I) form hydrogen‐bonded chains, while those of (III) and (V) form hydrogen‐bonded sheets, albeit with slightly different architectures. Molecules of 3‐tert‐butyl‐5‐(4‐methylbenzylamino)‐1‐phenyl‐1H‐pyrazole, C₂₁H₂₅N₃, (II), are linked into hydrogen‐bonded dimers by a combination of N—H...π(arene) and C—H...π(arene) hydrogen bonds, while those of 3‐tert‐butyl‐5‐(4‐chlorobenzylamino)‐1‐phenyl‐1H‐pyrazole, C₂₀H₂₂ClN₃, (IV), form hydrogen‐bonded chains of rings which are themselves linked into sheets by an aromatic π–π stacking interaction. Simple hydrogen‐bonded chains built from a single N—H...O hydrogen bond are formed in 3‐tert‐butyl‐5‐(4‐nitrobenzylamino)‐1‐phenyl‐1H‐pyrazole, C₂₀H₂₂N₄O₂, (VI), while in 3‐tert‐butyl‐5‐(3,4,5‐trimethoxybenzylamino)‐1‐phenyl‐1H‐pyrazole, C₂₃H₂₉N₃O₃, (VII), which crystallizes with Z′ = 2 in the space group P, pairs of molecules are linked into two independent centrosymmetric dimers, one generated by a three‐centre N—H...(O)₂ hydrogen bond and the other by a two‐centre N—H...O hydrogen bond.