Hydrate isomerism in [Cu(en)2(H2O)1.935]2[Fe(CN)6]·4H2O

The title compound, bis[di­aqua­bis­(ethyl­enedi­amine‐κ²N,N′)copper(II)­] hexa­cyano­iron(II) tetrahydrate, [Cu(C₂H₈N₂)₂(H₂O)_1.935]₂[Fe(CN)₆]·4H₂O, was crystallized from an aqueous reaction mixture initially containing CuSO₄, K₃[Fe(CN)₆] and ethyl­enedi­amine (en) in a 3:2:6 molar ratio. Its structure is ionic and is built up of two crystallographically different cations, viz. [Cu(en)₂(H₂O)₂]²⁺ and [Cu(en)₂(H₂O)_1.87]²⁺, there being a deficiency of aqua ligands in the latter, [Fe(CN)₆]⁴⁻ anions and disordered solvent water mol­ecules. All the metal atoms lie on centres of inversion. The Cu atom is octahedrally coordinated by two chelate‐bonded en mol­ecules [mean Cu—N = 2.016 (2) Å] in the equatorial plane, and by axial aqua ligands, showing very long distances due to the Jahn–Teller effect [mean Cu—O = 2.611 (2) Å]. In one of the cations, significant underoccupation of the O‐atom site is observed, correlated with the appearance of a non‐coordinated water mol­ecule. This is interpreted as the partial contribution of a hydrate isomer. The [Fe(CN)₆]⁴⁻ anions form quite regular octahedra, with a mean Fe—C distance of 1.913 (2) Å. The dominant intermolecular interactions are cation–anion O—H⋯N hydrogen bonds and these inter­actions form layers parallel to (001).     

Counter‐anion role in the formation of two supramolecular complexes: [Ag2(DPP)2](ClO4)2·CH3CN and [Ag2(DPP)2(NO3)2] {DPP is N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine}

The title compounds, bis{μ‐N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine‐κ²N¹:P}disilver bis(perchlorate) acetonitrile monosolvate, [Ag₂(C₁₈H₁₇N₂P)₂](ClO₄)₂·CH₃CN, (1), and bis{μ‐N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine‐κ²N¹:P}bis[(nitrato‐κ²O,O)silver], [Ag₂(C₁₈H₁₇N₂P)₂(NO₃)₂], (2), each contain disilver macrocyclic [Ag₂(C₁₈H₁₇N₂P)₂]²⁺ cations lying about inversion centres. The cations are constructed by two N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine (DPP) ligands linking two Ag⁺ cations in a head‐to‐tail fashion. In (1), the unique Ag⁺ cation has a near‐linear coordination geometry consisting of one pyridine N atom and one P atom from two different DPP ligands. Two ClO₄⁻ anions doubly bridge two metallomacrocycles through Ag...O and N—H...O weak interactions to form a chain extending in the c direction. The half‐occupancy acetonitrile molecule lies with its methyl C atom on a twofold axis and makes a weak N...Ag contact. In (2), there are two independent [Ag(C₁₈H₁₇N₂P)]⁺ cations. The nitrate anions weakly chelate to each Ag⁺ cation, leading to each Ag⁺ cation having a distorted tetrahedral coordination geometry consisting of one pyridine N atom and one P atom from two different DPP ligands, and two chelating nitrate O atoms. Each dinuclear [Ag₂(C₁₈H₁₇N₂P)₂(NO₃)₂] molecule acts as a four‐node to bridge four adjacent equivalent molecules through N—H...O interactions, forming a two‐dimensional sheet parallel to the bc plane. Each sheet contains dinuclear molecules involving just Ag1 or Ag2 and these two types of sheet are stacked in an alternating fashion. The sheets containing Ag1 all lie near x = , , etc, while those containing Ag2 all lie near x = 0, 1, 2 etc. Thus, the two independent sheets are arranged in an alternating sequence at x = 0, , 1, etc. These two different supramolecular structures result from the different geometric conformations of the templating anions which direct the self‐assembly of the cations and anions.     

Bis[N‐(2‐hydroxy­ethyl)‐β‐alaninato]copper(II)

The Cu^II ion in the title complex, [Cu(C₅H₁₀NO₃)₂] or [Cu(He‐ala)₂] [He‐ala = N‐(2‐hydroxy­ethyl)‐β‐alaninate], resides at the inversion centre of a square bipyramid comprised of two facially arranged tridentate He‐ala ligands. Each He‐ala ligand binds to a Cu^II ion by forming one six‐membered β‐alaninate chelate ring in a twist conformation and one five‐membered ethanol­amine ring in an envelope conformation, with Cu—N = 2.017 (2) Å, Cu—O_COO = 1.968 (1) Å and Cu—O_OH = 2.473 (2) Å. The [Cu(He‐ala)₂] mol­ecules are involved in a network of O—H⋯O and N—H⋯O hydrogen bonds, forming layers parallel to the (10) plane. The layers are connected into a three‐dimensional structure by van der Waals inter­actions, so that the mol­ecular centres form pseudo‐face‐centered close packing.     

A dinuclear complex of cobalt(II) with 2,2′‐(1,4‐butane­diyl)­dibenz­imidazole

The title complex, [μ‐2,2′‐(1,4‐butane­diyl)di‐1H‐benzimidazole‐κ²N³:N^3′]bis{[2,2′‐(1,4‐butane­diyl)di‐1H‐benzimidazole‐κ²N³,N^3′](nitrato‐κO)cobalt(II)} dinitrate ethanol disolvate, [Co₂(NO₃)₂(C₁₈H₁₈N₄)₃](NO₃)₂·2C₂H₆O, was obtained from self‐assembly of cobalt(II) nitrate with 2,2′‐(1,4‐butane­diyl)dibenzimidazole (L). The complex molecule lies about an inversion centre and the flexible L ligands act in both bridging and chelating modes to form a dinuclear complex with unanticipated nine‐membered chelate rings. The unique uncoordinated nitrate anion is linked to the cation by pairs of N—H⋯O hydrogen bonds, which determine the overall cation conformation. Cation–anion sets are then linked by a further N—H⋯O hydrogen bond to generate a chain along [010]. Chains are linked by C—H⋯O hydrogen bonds to form sheets in the (100) plane.     

K2[Hg(SO3)2]·2.25H2O

The characteristic feature of the structure of the title compound, dipotassium bis(sulfito‐κS)mercurate(II) 2.25‐hydrate, is a layered arrangement parallel to (001) where each of the two independent [Hg(SO₃)₂]²⁻ anions are grouped into centrosymmetric pairs and are surrounded by two K⁺ cations to give the overall layer composition {K₂[Hg(SO₃)₂]₂}²⁻. The remaining cations and the uncoordinated water molecules are situated between these layers. Within the [Hg(SO₃)₂]²⁻ anions, the central Hg atoms are twofold coordinated by S atoms, with a mean Hg—S bond length of 2.384 (2) Å. The anions are slightly bent [174.26 (3) and 176.99 (3)°] due to intermolecular O...Hg interactions greater than 2.8 Å. All coordination polyhedra around the K⁺ cations are considerably distorted, with coordination numbers ranging from six to nine. Although the H atoms of the five water molecules (one with symmetry 2) could not be located, O...O separations between 2.80 and 2.95 Å suggest a system of medium to weak O—H...O hydrogen bonds which help to consolidate the structural set‐up. Differences and similarities between the bis(sulfito‐κS)mercurate(II) anions in the title compound and those in the related salts (NH₄)₂[Hg(SO₃)₂] and Na₂[Hg(SO₃)₂]·H₂O are discussed.     

Bis{4‐[N,N‐bis(2‐cyano­ethyl)­amino]­pyridine‐κN1}silver(I) perchlorate,with the perchlorate anion located in the cation cavity

The title complex, bis­[3,3′‐(pyridine‐4‐imino‐κN¹)­di­propane­nitrile]silver(I) perchlorate, [Ag(CEAP)₂]ClO₄ {CEAP is 4‐[N,N‐bis(2‐cyano­ethyl)­amino]­pyridine, C₁₁H₁₂N₄}, has been prepared and characterized. The unit cell consists of two crystallographically non‐equivalent mol­ecules. Cation cavities are constructed by [Ag(CEAP)₂]⁺ cations through hydrogen bonds, and the ClO₄⁻ anions are incorporated into the cavities in μ₄‐ and μ₂‐ClO₄⁻ bridging modes through C—H⃛O hydrogen bonds.     

N,N, N′, N′‐Tetrakis(diphenylphosphanyl)‐1, 3‐diaminobenzene as a Bis‐chelate Ligand in [1, 3‐{cis‐Mo(CO)4(PPh2)2N}2C6H4]

1, 3‐Diaminobenzene reacts readily with PPh₂Cl to give N, N, N′, N′‐tetrakis(diphenylphosphanyl)‐1, 3‐diaminobenzene ( 1 ) in excellent yield. The dinuclear complex [1, 3‐{cis‐Mo(CO)₄(PPh₂)₂N}₂C₆H₄] ( 2 ) is obtained in high yield from 1 and cis‐[Mo(CO)₄(NCEt)₂]. Compounds 1 and 2 were characterized by NMR spectroscopy (¹H, ¹³C, ³¹P) and by crystal structure determination. The latter shows the formation of a bis‐chelate complex with Mo‐P‐N‐P four‐membered rings.     

{4‐[(Carbamimidoylhydrazono)methyl‐κ2N1,N4]‐5‐hydroxymethyl‐2‐methylpyridinium‐3‐olate‐κO}(methanol‐κO)copper(II) dinitrate

The title compound, [Cu(C₉H₁₃N₅O₂)(CH₄O)](NO₃)₂, consists of square‐planar cationic complex units where the Cu^II centre is coordinated by an N,N′,O‐tridentate pyridoxal–aminoguanidine Schiff base adduct and a methanol molecule. The tridentate ligand is a zwitterion exhibiting an almost planar conformation. The dihedral angles between the mean planes of the pyridoxal ring and the six‐ and five‐membered chelate rings are all less than 2.0°. The charge on the complex cation is neutralized by two nitrate counter‐ions. Extensive N—H...O and C—H...O hydrogen bonding connects these ionic species and leads to the formation of layers. The pyridoxal hydroxy groups are the only fragments that deviate significantly from the flat layer structure; these groups are involved in O—H...O hydrogen bonding, connecting the layers into a three‐dimensional crystal structure.     

Bis(acesulfamato‐κ2O4,N)bis­(3‐methyl­pyridine)copper(II)

In the crystal structure of the title compound {systematic name: bis­[6‐methyl‐1,2,3‐oxa­thia­zin‐4(3H)‐one 2,2‐dioxide(1−)‐κ²N³,O⁴]bis­(3‐meth­yl­pyridine)copper(II)}, [Cu(C₄H₄NO₄S)₂(C₆H₇N)₂], the Cu^II centre resides on a centre of symmetry and has an octa­hedral geometry that is distorted both by the presence of four‐membered chelate rings and because of the Jahn–Teller effect. The equatorial plane is formed by the N atoms of two methyl­pyridine ligands and by the more basic O atoms of the acesulfamate ligands, while the weakly basic N atoms of these ligands are in elongated axial positions with a misdirected valence. The crystal is stabilized by two inter­molecular C—H⋯O inter­actions involving the methyl and CH groups, and the sulfonyl O atoms of the acesulfamate group.     

Three transition‐metal complexes with the macrocyclic ligand meso‐5,7,7,12,14,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane (L): [Cu(ClO4)2(L)], [Zn(NO3)2(L)] and [CuCl(L)(H2O)]Cl

The three transition‐metal complexes, (meso‐5,7,7,12,14,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane‐κ⁴N)bis(perchlorato‐κO)copper(II), [Cu(ClO₄)₂(C₁₈H₄₀N₄)], (I), (meso‐5,7,7,12,14,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane‐κ⁴N)bis(nitrato‐κO)zinc(II), [Zn(NO₃)₂(C₁₈H₄₀N₄)], (II), and aquachlorido(meso‐5,7,7,12,14,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane‐κ⁴N)copper(II) chloride, [CuCl(C₁₈H₄₀N₄)(H₂O)]Cl, (III), are described. The molecules display a very similarly distorted 4+2 octahedral environment for the cation [located at an inversion centre in (I) and (II)], defined by the macrocycle N₄ group in the equatorial sites and two further ligands in trans‐axial positions [two O–ClO₃ ligands in (I), two O–NO₂ ligands in (II) and one chloride and one aqua ligand in (III)]. The most significant difference in molecular shape resides in these axial ligands, the effect of which on the intra‐ and intermolecular hydrogen bonding is discussed. In the case of (I), all strong hydrogen‐bond donors are saturated in intramolecular interactions, while weak intermolecular C—H...O contacts result in a three‐dimensional network. In (II) and (III), instead, there are N—H and O—H donors left over for intermolecular interactions, giving rise to the formation of strongly linked but weakly interacting chains.     

Bis(acesulfamato‐κ2N3,O4)bis­(2‐amino­pyrimidine‐κN1)copper(II)

In the crystal structure of the title compound, bis­(2‐amino­pyrimidine‐κN¹)bis­[6‐meth­yl‐1,2,3‐oxathia­zin‐4(3H)‐one 2,2‐dioxide(1−)‐κ²N³,O⁴]copper(II), [Cu(C₄H₄NO₄S)₂(C₄H₅N₃)₂], the first mixed‐ligand complex of acesulfame, the Cu^II centre resides on a centre of symmetry and has an octa­hedral geometry that is distorted both by the presence of four‐membered chelate rings and by the Jahn–Teller effect. The equatorial plane is formed by the N atoms of two amino­pyrimidine (ampym) ligands and by the weakly basic carbonyl O atoms of the acesulfamate ligands, while the more basic deprotonated N atoms of these ligands are in the elongated axial positions with a strong misdirected valence. The crystal is stabilized by pyrimidine ring stacking and by inter­molecular hydrogen bonding involving the NH₂ moiety of the ampym ligand and the carbon­yl O atom of the acesulfamate moiety.     

The cyclic vanadylacetate (C24H20P)[V4O8(C2H3O2)4(NO3)]

In the title complex, tetraphenylphosphonium μ₄‐nitrato‐κ⁴O‐cyclo‐tetrakis(μ‐acetato‐O:O′)tetra‐μ‐oxo‐tetrakis[oxovana‐dium(V)], the anion lies about a twofold axis and consists of the cyclic [V₄O₈] unit coordinated by four acetato ligands with interatomic V?V distances of 3.269 (1) and 3.273 (1) Å. The double‐bonded O atom [N=O 1.102 (6) and N—O 1.268 (4) Å] of the nitrato ligand links the four V atoms with V—O bond distances of 2.613 (2) and 2.813 (2) Å. The negative charge of the complex is balanced by tetraphenyl­phosphonium cations occupying the Na positions in the NaCl‐type ionic packing of the structure.     

Two isomorphous ZnII/CoII complexes with tri‐tert‐butoxysilanethiol and histamine,and (4‐hydroxymethyl‐1H‐imidazole‐κN)bis(tri‐tert‐butoxysilanethiolato‐κ2O,S)zinc(II)

The complexes [2‐(1H‐imidazol‐4‐yl‐κN³)ethylamine‐κN]bis(tri‐tert‐butoxysilanethiolato‐κS)cobalt(II), [Co(C₁₂H₂₇O₃SSi)₂(C₅H₉N₃)], and [2‐(1H‐imidazol‐4‐yl‐κN³)ethylamine‐κN]bis(tri‐tert‐butoxysilanethiolato‐κS)zinc(II), [Zn(C₁₂H₂₇O₃SSi)₂(C₅H₉N₃)], are isomorphous. The central Zn^II/Co^II ions are surrounded by two S atoms from the tri‐tert‐butoxysilanethiolate ligand and by two N atoms from the chelating histamine ligand in a distorted tetrahedral geometry, with two intramolecular N—H...O hydrogen‐bonding interactions between the histamine NH₂ groups and tert‐butoxy O atoms. Molecules of the complexes are joined into dimers via two intermolecular bifurcated N—H...(S,O) hydrogen bonds. The Zn^II atom in [(1H‐imidazol‐4‐yl‐κN³)methanol]bis(tri‐tert‐butoxysilanethiolato‐κ²O,S)zinc(II), [Zn(C₁₂H₂₇O₃SSi)₂(C₄H₆N₂O)], is five‐coordinated by two O and two S atoms from the O,S‐chelating silanethiolate ligand and by one N atom from (1H‐imidazol‐4‐yl)methanol; the hydroxy group forms an intramolecular hydrogen bond with sulfur. Molecules of this complex pack as zigzag chains linked by N—H...O hydrogen bonds. These structures provide reference details for cysteine‐ and histidine‐ligated metal centers in proteins.     

Comparison of two polymeric transition metal complexes with 1,4‐benzenedicarboxylate ions as bridging ligands, [Co(C8H4O4)(C12H8N2)(H2O)] and [Cu(C8H4O4)(C10H9N3)]·H2O

The title complexes, catena‐poly[[aqua(1,10‐phenanthroline‐κ²N,N′)­cobalt(II)]‐μ‐benzene‐1,4‐di­carboxyl­ato‐κ²O¹:O⁴], [Co(C₈H₄O₄)(C₁₂H₈N₂)(H₂O)], (I), and catena‐poly[[[(di‐2‐pyridyl‐κN‐amine)copper(II)]‐μ‐benzene‐1,4‐di­carboxyl­ato‐κ⁴O¹,O^1′:O⁴,O^4′] hydrate], [Cu(C₈H₄O₄)(C₁₀H₉N₃)]·H₂O, (II), take the form of zigzag chains, with the 1,4‐benzene­di­carboxyl­ate ion acting as an amphimonodentate ligand in (I) and a bis‐bidentate ligand in (II). The Co^II ion in (I) is five‐coordinate and has a distorted trigonal–bipyramidal geometry. The Cu^II ion in (II) is in a very distorted octahedral 4+2 environment, with the octahedron elongated along the trans O—Cu—O bonds and with a trans O—Cu—O angle of only 137.22 (8)°.     

Hydrogen bonding and π–π interactions in the cocrystal salt [Fe(bpe)2(H2O)4](TCEP)2·2(bpe) [bpe is trans‐1,2‐bis(pyridin‐4‐yl)ethene and TCEP is 1,1,3,3‐tetracyano‐2‐ethoxypropenide]

The cocrystal salt tetraaquabis[trans‐1,2‐bis(pyridin‐4‐yl)ethene‐κN]iron(II) bis(1,1,3,3‐tetracyano‐2‐ethoxypropenide)–trans‐1,2‐bis(pyridin‐4‐yl)ethene (1/2), [Fe(C₁₂H₁₀N₂)₂(H₂O)₄](C₉H₅N₄O)₂·2C₁₂H₁₀N₂, is a rare example of a mononuclear Fe^II compound with trans‐1,2‐bis(pyridin‐4‐yl)ethane (bpe) ligands. The complex cation resides on a crystallographically imposed inversion center and exhibits a tetragonally distorted octahedral coordination geometry. Both the symmetry‐independent bpe ligand and the cocrystallized bpe molecule are essentially planar. The 1,1,3,3‐tetracyano‐2‐ethoxypropenide counter‐ion is nonplanar and the bond lengths are consistant with significant electron delocalization. The extended structure exhibits an extensive O—H…N hydrogen‐bonding network with layers of complex cations joined by the cocrystallized bpe. Both the coordinated and the cocrystallized bpe are involved in π–π interactions. Hirshfeld and fingerprint plots reveal the important intermolecular interactions. Density functional theory was used to estimate the strengths of the hydrogen‐bonding and π–π interactions, and suggest that the O—H…N hydrogen bonds enhance the strength of the π‐interactions by increasing the polarization of the pyridine rings.     

(2,6‐Bis{1‐[4‐(dimethylamino)phenylimino]ethyl}pyridine)dichlorido(triphenylphosphine‐κP)ruthenium(II): a zigzag chain of fused centrosymmetric R22(12) rings

The title compound, [RuCl₂(C₂₅H₂₉N₅)(C₁₈H₁₅P)], a transfer hydrogenation catalyst, is supported by an N,N′,N′′‐tridentate pyridine‐bridged ligand and triphenylphosphine. The Ru^II centre is six‐coordinated in a distorted octahedral arrangement, with the two Cl atoms located in the axial positions, and the pyridine (py) N atom, the two imino N atoms and the triphenylphosphine P atom located in the equatorial plane. The two equatorial Ru—N_imino distances (mean 2.093 Å) are substantially longer than the equatorial Ru—N_py bond [1.954 (4) Å]. It is observed that the N_imino—M—N_py bond angle for the five‐membered chelate rings of 2,6‐bis(imino)pyridine‐based complexes is inversely related to the magnitude of the M—N_py bond. The title structure is stabilized by intra‐ and intermolecular C—H...Cl hydrogen bonds, as well as by intramolecular π–π stacking interactions between the aromatic rings belonging to the triphenylphosphine ligand and the dimethylaminophenyl fragment. The intermolecular hydrogen bonds form an R₂²(12) ring and a zigzag chain of fused centrosymmetric rings running parallel to the [100] direction.     

Completing the bis[hydroxybis(pyridin‐2‐yl)methanesulfonato‐κ3N,O,N′]MII series (M = Mn to Zn) with the copper(II) and cobalt(II) structures

The Cu^II complex bis[hydroxybis(pyridin‐2‐yl)methanesulfonato‐κ³N,O,N′]copper(II) hexahydrate, [Cu(C₁₁H₉N₂O₄S)₂]·6H₂O, (I), crystallizes in the space group P, compared with P2₁/c for the anhydrous Co^II analogue bis[hydroxybis(pyridin‐2‐yl)methanesulfonato‐κ³N,O,N′]cobalt(II), [Co(C₁₁H₉N₂O₄S)₂], (II). However, both molecules sit on a crystallographic inversion centre and are thus very similar in appearance. Jahn–Teller elongation of the Cu—O bonds [2.347 (3) Å in (I) and 2.064 (2) Å in (II)] influences the S—O bond lengths, which are all around 1.455 (3) Å in (I) and 1.436 (2)–1.473 (2) Å in (II).     

Two different one‐dimensional structural motifs in [catena‐{Cu(tacn)}2Pd(CN)4]Br2·[catena‐Cu(tacn)Pd(CN)4]2·H2O (tacn is 1,4,7‐triazacyclononane)

The title compound, catena‐poly[[bis[(triazacyclononane‐κ³N,N′,N′′)copper(II)]‐di‐μ‐cyanido‐κ⁴N:C‐palladate(II)‐di‐μ‐cyanido‐κ⁴C:N] dibromide bis[[(triazacyclononane‐κ³N,N′,N′′)copper(II)]‐μ‐cyanido‐κ²N:C‐[dicyanidopalladate(II)]‐μ‐cyanido‐κ²C:N] monohydrate], {[Cu₂Pd(CN)₄(C₆H₁₅N₃)₂]Br₂·[Cu₂Pd₂(CN)₈(C₆H₁₅N₃)₂]·H₂O}_n, (I), was isolated from an aqueous solution containing tacn·3HBr (tacn is 1,4,7‐triazacyclononane), Cu²⁺ and tetracyanidopalladate(2−) anions. The crystal structure of (I) is essentially ionic and built up of 2,2‐electroneutral chains, viz. [Cu(tacn)(NC)–Pd(CN)₂–(CN)–], positively charged 2,4‐ribbons exhibiting the composition {[Cu(tacn)(NC)₂–Pd(CN)₂–Cu(tacn)]²ⁿ⁺}_n, bromide anions and one disordered water molecule of crystallization. The O atom of the water molecule occupies two unique crystallographic positions, one on a centre of symmetry, which is half occupied, and the other in a general position with one‐quarter occupancy. One of the tacn ligands also exhibits disorder. The formation of two different types of one‐dimensional structural motif within the same structure is a unique feature of this compound.     

mer‐Diaquabis(1H‐imidazole‐κN3)[orotato(2–)]cobalt(II)

In the title complex, mer‐diaqua[2,6‐dioxo‐1,2,3,6‐tetrahydropyrimidine‐4‐carboxylato(2−)]bis(1H‐imidazole‐κN³)cobalt(II), [Co(C₅H₂N₂O₄)(C₃H₄N₂)₂(H₂O)₂], the Co^II ion is coordinated by a deprotonated N atom and the carboxylate O atom of the orotate ligand, two imidazole N atoms and two aqua ligands in a distorted octahedral geometry. The title complex exists as discrete doubly hydrogen‐bonded dimers, and a three‐dimensional network of O—H...O and N—H...O hydrogen bonds and weak π–π interactions is responsible for crystal stabilization.