N,N′‐Bis(2‐pyridylmeth­yl)ferrocene‐1,1′‐diyldicarboxamide and N,N′‐bis­(3‐pyridylmeth­yl)ferrocene‐1,1′‐diyldicarboxamide

The mol­ecules of N,N′‐bis­(2‐pyridylmeth­yl)ferrocene‐1,1′‐diyl­dicarboxamide, [Fe(C₁₂H₁₁N₂O)₂], contain intra­molecular N—H⋯N hydrogen bonds and are linked into sheets by three independent C—H⋯O hydrogen bonds. The mol­ecules of the isomeric compound N,N′‐bis­(3‐pyridylmeth­yl)ferrocene‐1,1′‐diyldicarboxamide lie across inversion centres, and the mol­ecules are linked into sheets by a combination of N—H⋯N hydrogen bonds and π–π stacking inter­actions between pyridyl groups.     

C—H⋯O,C—H⋯π and π–π inter­actions in three benzofuran‐2‐yl ketone derivatives

The mol­ecules of 2‐benzoyl‐1‐benzofuran, C₁₅H₁₀O₂, (I), inter­act through double C—H⋯O hydrogen bonds, forming dimers that are further linked by C—H⋯O, C—H⋯π and π–π inter­actions, resulting in a three‐dimensional supramolecular network. The dihedral angle between the benzo­yl and benzofuran fragments in (I) is 46.15 (3)°. The mol­ecules of bis­(5‐bromo‐1‐benzofuran‐2‐yl) ketone, C₁₇H₈Br₂O₃, (II), exhibit C₂ symmetry, with the carbon­yl group (C=O) lying along the twofold rotation axis, and are linked by a combination of C—H⋯O and C—H⋯π inter­actions and Br⋯Br contacts to form sheets. The stability of the mol­ecular packing in 3‐mesit­yl‐3‐methyl­cyclo­but­yl 3‐methyl­naphtho[1,2‐b]furan‐2‐yl ketone, C₂₈H₂₈O₂, (III), arises from C—H⋯π and π–π stacking inter­actions. The fused naphthofuran moiety in (III) is essentially planar and makes a dihedral angle of 81.61 (3)° with the mean plane of the trimethyl­benzene ring.     

Secondary inter­actions in two related terphenyl derivatives: 2′,5′‐dimethyl‐p‐terphenyl and 2′,5′‐bis­(bromo­meth­yl)‐p‐terphen­yl

In 2′,5′‐dimethyl‐p‐terphenyl, C₂₀H₁₈, which displays pseudosymmetry (the true space group is Pna2₁, but less satisfactory refinement can also be achieved in Pbcn), the mol­ecules are linked into chains by two short C—H⋯π inter­actions to the centroid of the central ring. In 2′,5′‐bis­(bromo­meth­yl)‐p‐terphenyl, C₂₀H₁₆Br₂, the polar CH₂Br groups cause mol­ecules to aggregate via C—H⋯Br and Br⋯Br inter­actions, forming a layer structure, in which the phenyl rings project outwards from the central, more polar, region.     

The cocrystal of 3‐hydroxy‐2‐naphthoic acid and 4,4′‐bipyridine

4,4′‐Bipyridine cocrystallizes with 3‐hydroxy‐2‐naphthoic acid in a 1:2 ratio to give a centrosymmetric three‐component supra­molecular adduct, namely 3‐hydroxy‐2‐naphthoic acid–4,4′‐bipyridine (2/1), C₁₁H₈O₃·0.5C₁₀H₈N₂, in which 4,4′‐bipyridine is located on an inversion center. The pyridine–carboxylic acid heterosynthon generates an infinite one‐dimensional hydrogen‐bonded chain viaπ–π inter­actions between naphthyl and 4,4′‐bipyridine groups. The one‐dimensional chains are further assembled into a three‐dimensional network by weak C—H⋯π inter­actions between pyridyl and naphthyl rings, and C—H⋯O inter­actions between 3‐hydroxy‐2‐naphthoic acid mol­ecules.     

Naphthalene‐1,7‐diol

The asymmetric unit of the title compound, C₁₀H₈O₂, contains two planar symmetry‐independent mol­ecules linked by an O—H⋯O hydrogen bond. In the crystal structure, mol­ecules are linked into infinite chains of rings, formed by a combination of O—H⋯O and C—H⋯O hydrogen bonds, and additionally reinforced by π–π stacking inter­actions. Adjacent chains are connected by weak C—H⋯π inter­actions.     

β‐Lapachone

The most remarkable aspect of the crystal structure of the title compound (systematic name: 3,4‐dihydro‐2,2‐dimethyl‐2H‐naphtho[1,2‐b]pyran‐5,6‐dione), C₁₅H₁₄O₃, is that a π‐stacking inter­action is present between the two naphthalene ring systems of symmetry‐related mol­ecules. Apart from these π–π inter­actions, different mol­ecules are held together by weak C—H⋯O hydrogen‐bonding inter­actions.     

[1,3‐Bis(2‐ethoxy­phenyl)imidazolidin‐2‐yl­idene]bromo­(cyclo­octa‐1,5‐diene)­rhodium(I)

The title complex, [RhBr(C₈H₁₂)(C₁₉H₂₂N₂O₂)], has a distorted square‐planar geometry. There are two mol­ecules, A and B, in the asymmetric unit. The Rh—C bond distance between the N‐heterocyclic ligand and the metal atom is 2.039 (2) Å in mol­ecule A and 2.042 (2) Å in mol­ecule B. The angle between the carbene heterocycle and the coordination plane is 87.56 (12)° in mol­ecule A and 87.03 (11)° in mol­ecule B. It is shown that the average Rh—C(COD) (COD is cyclo­octa­diene) distance is linearly dependent on the Rh—C(imidazolidine) distance in this type of compound. This can be ascribed to the steric hindrance produced by the packing. The crystal structure contains intra­molecular C—H⋯O and inter­molecular C—H⋯Br inter­actions.     

1‐Benzyl‐3,3‐dichloro‐1H‐indol‐2(3H)‐one

The title compound, C₁₅H₁₁Cl₂NO, was synthesized from N‐­benzyl­isatin. The compound crystallizes as stacks of mol­ecules running down the c axis. Mol­ecules within each of these stacks inter­act with each other through π–π and C—H⋯π inter­actions, and inter­act with neighbouring stacks through C—H⋯O inter­actions.     

2,3‐Difluoro‐4‐formyl­phenyl­boronic acid

The mol­ecule of the title compound, 2,3‐F₂‐4‐(CHO)C₆H₂B(OH)₂ or C₇H₅BF₂O₃, contains a formyl group coplanar with the benzene ring. The boronic acid group is twisted with respect to the benzene ring plane. The mol­ecules are organized into infinite chains via inter­molecular O—H⋯O hydrogen bonds. These chains are additionally connected via strong O—H⋯O hydrogen bonds, producing a folded layer structure perpendicular to the a axis. These layers are paired due to B⋯F inter­actions.     

N‐Cyclo­hexyl‐2‐[5‐(4‐pyridyl)‐4‐(p‐tolyl)‐4H‐1,2,4‐triazol‐3‐yl­sulfanyl]­acetamide dihydrate

In the title compound, C₂₂H₂₅N₅OS·2H₂O, the mol­ecules are stacked in columns running along the b axis. In this arrangemant, the mol­ecules are linked to each other by a combination of one two‐centre N—H⋯O hydrogen bond and four two‐centre O—H⋯O hydrogen bonds containing two types of ring motif, viz.R₄⁴(10) and R₃³(11). In the crystal structure, centrosymmetric π–π inter­actions between the triazole rings, with a distance of 3.691 (2) Å between the ring centroids, also affect the packing of the mol­ecules.     

Ethyl N‐[2‐(hydroxy­acetyl)­phenyl]­carbamate,ethyl N‐[2‐(hydroxy­acetyl)‐4‐iodo­phenyl]­carbamate and ethyl N‐[2‐(hydroxy­acetyl)‐4‐methyl­phenyl]­carbamate

In ethyl N‐[2‐(hydroxy­acetyl)phenyl]carbamate, C₁₁H₁₃NO₄, all of the non‐H atoms lie on a mirror plane in the space group Pnma; the mol­ecules are linked into simple chains by a single C—H⋯O hydrogen bond. The mol­ecules of ethyl N‐[2‐(hydroxy­acetyl)‐4‐iodo­phenyl]carbamate, C₁₁H₁₂INO₄, are linked into sheets by a combination of O—H⋯I and C—H⋯O hydrogen bonds and a dipolar I⋯O contact. Ethyl N‐­[2‐(hydroxy­acetyl)‐4‐methyl­phenyl]carbamate, C₁₂H₁₅NO₄, crystallizes with Z′ = 2 in the space group P; pairs of mol­ecules are weakly linked by an O—H⋯O hydrogen bond and these aggregates are linked into chains by two independent aromatic π–π stacking inter­actions.     

1‐Acetyl‐3‐ferrocenyl‐5‐methyl‐1H‐pyrazole and 1‐acetyl‐5‐ferrocenyl‐3‐(2‐pyrid­yl)‐1H‐pyrazole

Mol­ecules of 1‐acetyl‐3‐ferrocenyl‐5‐methyl‐1H‐pyrazole, [Fe(C₅H₅)(C₁₁H₁₁N₂O)], form a centrosymmetric dimer generated by a combination of one C—H⋯π(pyrazole) and one C—H⋯π(cyclo­penta­dienyl) inter­action. The dimers are linked by C—H⋯π inter­actions, involving the pyrazole rings as acceptors, into layers parallel to (10). Mol­ecules of 1‐acetyl‐5‐ferrocenyl‐3‐(2‐pyrid­yl)‐1H‐pyrazole, [Fe(C₅H₅)(C₁₅H₁₂N₃O)], are linked by C—H⋯O inter­actions into a chain running in the [010] direction. Two chains of this type passing through each unit cell are connected by O⋯π(pyridyl) inter­actions into an [010] double chain.     

Three isomeric forms of hydroxyphenyl‐2‐oxazoline: 2‐(2‐hydroxyphenyl)‐2‐oxazoline, 2‐(3‐hydroxyphenyl)‐2‐oxazoline and 2‐(4‐hydroxyphenyl)‐2‐oxazoline

Crystal structures are reported for three isomeric compounds, namely 2‐(2‐hydroxy­phenyl)‐2‐oxazoline, (I), 2‐(3‐hydroxy­phenyl)‐2‐oxazoline, (II), and 2‐(4‐hydroxy­phenyl)‐2‐oxazoline, (III), all C₉H₉NO₂ [systematic names: 2‐(4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenol, (I), 3‐(4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenol, (II), and 4‐(4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenol, (III)]. In these compounds, the deviation from coplanarity of the oxazoline and benzene rings is dependent on the position of the hydroxy group on the benzene ring. The coplanar arrangement in (I) is stabilized by a strong intra­molecular O—H⋯N hydrogen bond. Surprisingly, the 2‐oxazoline ring in mol­ecule B of (II) adopts a ³T₄ (^C2T_C3) conformation, while the 2‐oxazoline ring in mol­ecule A, as well as that in (I) and (III), is nearly planar, as expected. Tetra­mers of mol­ecules of (II) are formed and they are bound together via weak C—H⋯N hydrogen bonds. In (III), strong inter­molecular O—H⋯N hydrogen bonds and weak intra­molecular C—H⋯O hydrogen bonds lead to the formation of an infinite chain of mol­ecules perpendicular to the b direction. This paper also reports a theoretical investigation of hydrogen bonds, based on density functional theory (DFT) employing periodic boundary conditions.     

(Z)‐2‐(3‐Methoxy­benzyl­idene)‐1‐aza­bicyclo­[2.2.2]octan‐3‐one

The crystal structure of the title compound, C₁₅H₁₇NO₂, contains two nearly identical but crystallographically independent mol­ecules, each with a double bond connecting an aza­bicyclic ring system to a 3‐methoxy­benzyl­idene moiety. The space group is triclinic P. The benzene ring is twisted by 18.44 (5) and 22.35 (4)° with respect to the plane of the double bond connected to the azabicyclic ring system for the two mol­ecules. In addition to C—H⋯π inter­actions, mol­ecules are held together in the solid state by van der Waals inter­actions.     

trans‐Bis[1‐benzyl‐3‐(2,3,4,5,6‐penta­fluoro­benz­yl)benzimidazol‐2‐yl­idene]­dibromo­palladium(II)

The title compound, [PdBr₂(C₂₁H₁₃F₅N₂)₂], crystallizes with two independent centrosymmetric conformational isomers having a square‐planar coordination at the Pd atom. The conformational isomers differ by the ligands having a cis or trans orientation of their benzyl and pentafluorobenzyl rings with respect to the benzimidazole ring plane. The benzimidazole rings are rotated with respect to the coordination plane of the metal by 79.1 (2) and 75.2 (1)° for mol­ecules A and B, respectively. The Pd—Br bond lengths are 2.4218 (8) and 2.4407 (10) Å for mol­ecules A and B, respectively, and the Pd—C bond lengths are 2.030 (8) and 2.018 (9) Å. The crystal structure contains two types of C—H⋯F and one type of C—H⋯Br intra­molecular contact, as well as C—H⋯π inter­actions.     

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.     

Hydrogen bonding in meso‐4,5‐diphenyl‐3,6‐diaza­octane‐1,8‐diol: the formation of one‐dimensional linear chains of edge‐fused rings

The molecule of the title compound, C₁₈H₂₄N₂O₂, resides on a crystallographic inversion centre. The mol­ecule adopts a transoid conformation with respect to the central C—C single bond and is in the meso form. A polarimetric study of the compound did not show any optical activity, indicating that the compound is a racemic mixture entirely consistent with the centrosymmetric space group. In the mol­ecule, there is one intra­molecular N—H⋯O inter­action, resulting in the formation of a five‐membered ring. In the crystal structure, inter­molecular O—H⋯N and C—H⋯O inter­actions are also observed. These inter­actions form an R₂²(9) ring and one‐dimensional linear chains of edge‐fused rings running parallel to the [010] direction, which stabilize the crystal packing.     

(2‐Meth­oxy‐3‐pyrid­yl)boronic acid

The structure of the title compound, 2‐CH₃O‐C₅H₃N–3‐B(OH)₂ or C₆H₈BNO₃, comprises two crystallographically independent mol­ecules. The molecules are linked to each other by inter­molecular O—H⋯N and C—H⋯O bonds to produce an infinite chain, while a two‐dimensional structure is formed as a result of π–π inter­actions of planar mol­ecules.     

3,3′‐Dihydr­oxy‐5,5,5′,5′‐tetra­methyl‐2,2′‐thio­dicyclo­hex‐2‐en‐1‐one

Mol­ecules of the title compound, C₁₆H₂₂O₄S, have twofold crystallographic symmetry and are stabilized by strong intra­molecular O—H⋯O hydrogen bonds and very weak inter­molecular C—H⋯O hydrogen bonds, forming layers normal to the c axis. The mol­ecular structure is compared with those of the Se‐ and CH₂‐bridged analogues.     

N—H⋯N and C—H⋯π inter­actions in 4‐amino‐3‐methyl‐5‐(p‐tol­yl)‐4H‐1,2,4‐triazole and 4‐amino‐3‐methyl‐5‐phenyl‐4H‐1,2,4‐triazole

The title compounds, C₁₀H₁₂N₄, (I), and C₉H₁₀N₄, (II), have been synthesized and characterized both spectroscopically and structurally. The dihedral angles between the triazole and benzene ring planes are 26.59 (9) and 42.34 (2)°, respectively. In (I), mol­ecules are linked principally by N—H⋯N hydrogen bonds involving the amino NH₂ group and a triazole N atom, forming R₄⁴(20) and R₂⁴(10) rings which link to give a three‐dimensional network of mol­ecules. The hydrogen bonding is supported by two different C—H⋯π inter­actions from the tolyl ring to either a triazole ring or a tolyl ring in neighboring mol­ecules. In (II), inter­molecular hydrogen bonds and C—H⋯π inter­actions produce R₃⁴(15) and R₄⁴(21) rings.