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1.  1-Heptyl-1,3,6,8-tetraaza­tricyclo­[4.3.1.13,8]undecan-1-ium iodide 
The title compound C14H29N4 +·I− salt, was obtained by the reaction of cage adamanzane-type aminal 1,3,6,8-tetra­aza­tricyclo­[4.3.1.13,8]undecane with heptyl iodide. In the cation, the bond lengths and angles are within normal ranges, except for one N—C(ring) bond distance of 1.542 (3) Å, which is unexpectedly long compared with related compounds. In the crystal, ions are linked through C—H⋯I hydrogen bonds. The crystal studied was a non-merohedral twin with a minor twin domain of 6.56 (5)%.
doi:10.1107/S1600536811036403
PMCID: PMC3201392  PMID: 22064969
2.  Crystal structure of (3E,5E)-3,5-bis­[4-(di­ethyl­aza­nium­yl)benzyl­idene]-1-methyl-4-oxopiperidin-1-ium trichloride dihydrate: a potential biophotonic material 
A stable oxopiperidinium trication salt was synthesized. In the crystal, N—H⋯Cl, C—H⋯Cl and C—H⋯O hydrogen bonds link cations and anions into a three-dimensional network.
In the trication of the title hydrated mol­ecular salt, C28H40N3O3+·3Cl−·2H2O, the central heterocyclic ring adopts a sofa conformation, with the exocyclic N—C bond in an equatorial orientation. The dihedral angles between the planar part of this heterocyclic ring and the two almost flat side-chain fragments, which include the aromatic ring and bridging atoms, are 28.8 (1) and 41.1 (1)°. Both di­ethyl­aza­niumyl substituents have a tetra­hedral geometry, while the dihedral angles between the above-mentioned flat part of the aryl fragments and the imaginary planes drawn through atoms C—N—C of the di­ethyl­aza­niumyl substituents are 86.3 (2) and 80.4 (1)°, respectively. In the crystal, N—H⋯Cl hydrogen bonds link the cations and anions into [100] chains. The chains are cross-linked by numerous C—H⋯O and C—H⋯Cl inter­actions, generating a three-dimensional network. One of the chloride ions is disordered over two adjacent positions in a 0.895 (4):0.105 (4) ratio.
doi:10.1107/S2056989015020952
PMCID: PMC4719826  PMID: 26870417
crystal structure; X-ray analysis; piperidinium salt; hydrogen bonding; biophotonic material
3.  Synthesis and structural studies of a new class of quaternary ammonium salts, which are derivatives of cage adamanzane type aminal 1, 3, 6, 8-tetraazatricyclo[4.3.1.13,8]undecane (TATU) 
Background
Novel mono N-alkyl quaternary ammonium salts (3a-f) were prepared using the Menschutkin reaction from the cage adamanzane type aminal 1,3,6,8-tetraazatricyclo[4.3.1.13,8]undecane (TATU) and alkyl iodides, such as methyl, ethyl, propyl, butyl, pentyl and hexyl iodide (2a-f), in dry acetonitrile at room temperature.
Results
The structures of these new quaternary ammonium salts were established using various spectral and electrospray ionization mass spectrometry (ESI-MS) analyses. Compound (3b) was also analyzed using X-ray crystallography.
Conclusion
It was noted that alkyl chain length did not significantly affect the reaction because all employed alkyl iodide electrophiles reacted in a similar fashion with the aminal 1 to produce the corresponding mono N-quaternary ammonium salts, which were characterized by spectroscopic and analytical techniques.
doi:10.1186/1752-153X-5-55
PMCID: PMC3189110  PMID: 21933409
4.  Crystal structure of bis­[4′-(1,4,7,10-tetra­oxa-13- aza­cyclo­penta­decan-13-yl)-2,2′:6′,2′′-terpyridine]­cobalt(III) tris­(perchlorate) methanol monosolvate monohydrate 
The title compound, bis­[4′-(1,4,7,10-tetra­oxa-13-aza­cyclo­penta­decan-13-yl)-2,2′:6′,2"-terpyridine]­cobalt(III) tris­(perchlorate) methanol monosolvate monohydrate, is a novel complex in which the metal centre is hexa­coordinated.
In the title compound, [Co(C25H30N4O4)2](ClO4)3·CH3OH·H2O, the metal atom is coordinated by two tridentate crown ether terpyridine ligands, forming a distorted CoN6 octa­hedron. The three pyridine rings in each crown–terpyridine ligand are approximately coplanar [maximum deviations = 0.088 (12) and 0.102 (15) Å] and the mean planes through the three pyridine rings are perpendicular to each other, making a dihedral angle of 89.95 (17)°. An intra­molecular C—H⋯π inter­action is observed between the two terpyridine ligands. In the crystal, O—H⋯O and C—H⋯O hydrogen bonds, a π–π stacking inter­action [centroid–centroid distance = 3.923 (7) Å] and a C—H⋯π inter­action connect the complex cation, the perchlorate anions and the two types of solvent molecules, forming a three-dimensional network.
doi:10.1107/S2056989015014164
PMCID: PMC4571376  PMID: 26396775
crystal structure; terpyridine; crown ether; hydrogen bonding; C—H⋯π inter­actions; π–π stacking inter­actions
5.  Diaqua­(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4 N 1,N 4,N 8,N 11)copper(II) dihepta­noate dihydrate 
The CuII atom in the title salt, [Cu(C10H24N4)(H2O)2][CH3(CH2)5CO2]2·2H2O, is chelated by the four N atoms of the 1,4,8,11-tetra­aza­cyclo­tetra­decane (cyclam) ligand and is coordinated by two water mol­ecules in a tetra­gonally Jahn–Teller-distorted octa­hedral geometry. The CuII atom lies on a center of inversion. The cations, anions and uncoordinated water mol­ecules are linked by N—H⋯O and O—H⋯O hydrogen bonds, forming a layer structure parallel to (100). The alkyl chain of the anion is disordered over two positions in a 0.82 (1):0.18 (1) ratio.
doi:10.1107/S1600536810025687
PMCID: PMC3007509  PMID: 21588132
6.  Diaqua­(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4 N 1,N 4,N 8,N 11)copper(II) bis­(4-methyl­benzoate) monohydrate 
The CuII atom in the title salt, [Cu(C10H24N4)(H2O)2](C8H7O2)2·H2O, is chelated by the four N atoms of the 1,4,8,11-tetra­aza­cyclo­tetra­decane (cyclam) ligand and is coordinated by two water mol­ecules in a Jahn–Teller-type of tetra­gonally distorted octa­hedral geometry. The cations, anions and lattice water mol­ecules are linked by N—H⋯O and O—H⋯O hydrogen bonds to form a layer structure parallel to (001).
doi:10.1107/S1600536810026012
PMCID: PMC3007233  PMID: 21588135
7.  Diaqua­(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4 N 1,N 4,N 8,N 11)copper(II) bis­(2,3,4,5,6-penta­fluoro­benzoate) dihydrate 
The CuII atom in the title salt, [Cu(C10H24N4)(H2O)2](C6F5CO2)2·2H2O, is chelated by the four N atoms of the 1,4,8,11-tetra­aza­cyclo­tetra­decane (cyclam) ligand and is coordinated by two water mol­ecules in a Jahn–Teller-type tetra­gonally distorted octa­hedral geometry. The CuII atom lies on a center of inversion. The cations, anions and uncoordinated water mol­ecules are linked by N—H⋯O and O—H⋯O hydrogen bonds, forming a layer structure parallel to (001).
doi:10.1107/S1600536810025705
PMCID: PMC3007516  PMID: 21588134
8.  Diaqua­(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4 N 1,N 4,N 8,N 11)copper(II) dideca­noate dihydrate 
The CuII atom in the title salt, [Cu(C10H24N4)(H2O)2][CH3(CH2)8CO2]2·2H2O, is chelated by the four N atoms of the 1,4,8,11-tetra­aza­cyclo­tetra­decane (cyclam) ligand and is coordinated by two water mol­ecules in a Jahn–Teller-type tetra­gonally distorted octa­hedral geometry. The CuII atom lies on a center of inversion. The cations, anions and uncoordinated water mol­ecules are linked by N—H⋯O and O—H⋯O hydrogen bonds, forming a layer structure parallel to (001).
doi:10.1107/S1600536810025699
PMCID: PMC3007572  PMID: 21588133
9.  Diaqua­(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4 N 1,N 4,N 8,N 11)copper(II) didodeca­noate dihydrate 
The title compound, [Cu(C10H24N4)(H2O)2][CH3(CH2)10CO2]2·2H2O, consists of one cationic copper(II) complex, two dodeca­noate anions and two water solvent mol­ecules. The CuII atom is located on an inversion center and is chelated by the four aza N atoms of the neutral 1,4,8,11-tetra­aza­cyclo­tetra­decane (cyclam) ligand and by two water mol­ecules in axial positions, giving an octa­hedral coordination geometry, distorted as a consequence of the Jahn–Teller effect. The uncoordinated water mol­ecules link the complex cations and the dodeca­noate counter-ions through O—H⋯O hydrogen bonding, forming a layer structure parallel to (001). Inter­molecular N—H⋯O inter­actions also occur.
doi:10.1107/S1600536811012773
PMCID: PMC3089101  PMID: 21754311
10.  Crystal structure of cis-aqua­chlorido­(rac-5,5,7,12,12,14-hexa­methyl-1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4 N)chromium(III) tetra­chlorido­zincate trihydrate from synchrotron data 
The CrIII ion in the title cationic complex is coordinated by four N atoms from the macrocyclic ligand, one water mol­ecule and one chloride in a cis geometry, displaying a distorted octa­hedral environment. The crystal packing is stabilized by N—H⋯Cl, O—H⋯Cl and O—H⋯O hydrogen bonds.
The structure of the title compound, cis-[CrCl(cycb)(H2O)][ZnCl4]·3H2O (cycb is rac-5,5,7,12,12,14-hexa­methyl-1,4,8,11-tetra­aza­cyclo­tetra­decane; C16H36N4), has been determined from synchrotron data. In the complex cation, the CrIII ion is bound by four N atoms from the tetra­dentate cycb ligand, a chloride ion and one water mol­ecule in a cis arrangement, displaying a distorted octa­hedral coordination geometry. The distorted tetra­hedral [ZnCl4]2− anion and three additional water mol­ecules remain outside the coordination sphere. The Cr—N(cycb) bond lengths are in the range of 2.0837 (14) to 2.1399 (12) Å while the Cr—Cl and Cr—(OH2) bond lengths are 2.2940 (8) and 2.0082 (13) Å, respectively. The crystal packing is stabilized by hydrogen-bonding inter­actions between the N—H groups of the macrocyclic ligand, the O—H groups of the water mol­ecules and the Cl atoms of the tetra­chlorido­zincate anion, leading to the formation of a three-dimensional network.
doi:10.1107/S2056989015015212
PMCID: PMC4555385  PMID: 26396846
crystal structure; synchrotron radiation; macrocyclic chromium(III) complex; chlorido ligand; aqua ligand; cis-geometry; hydrogen bonding
11.  Crystal structure of bis­[trans-(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4 N)bis­(thio­cyanato-κN)chromium(III)] tetra­chlorido­zincate from synchrotron data 
The CrIII atoms in the title compound show a distorted octa­hedral coordination with four N atoms of the cyclam ligand in the equatorial plane and two N-coordinated NCS− groups in axial positions. The macrocyclic ligands adopt trans-III configurations. The crystal packing is stabilized by N—H⋯S and N—H⋯Cl hydrogen bonds.
The structure of the title compound, [Cr(NCS)2(cyclam)]2[ZnCl4] (cyclam = 1,4,8,11-tetra­aza­cyclo­tetra­decane, C10H24N4), has been determined from synchrotron data. The asymmetric unit contains two independent halves of the CrIII complex cations and half of a tetra­chlorido­zincate anion. In each complex cation, the CrIII atom is coordinated by the four N atoms of the cyclam ligand in the equatorial plane and by two N-bound NCS− anions in a trans axial arrangement, displaying a distorted octa­hedral geometry with crystallographic inversion symmetry. The mean Cr—N(cyclam) and Cr—N(NCS) bond lengths are 2.065 (4) and 1.995 (6) Å, respectively. The macrocyclic cyclam moieties adopt centrosymmetric trans-III configurations with six- and five-membered chelate rings in chair and gauche configurations, respectively. The [ZnCl4]2− anion, which lies about a twofold rotation axis, has a slightly distorted tetra­hedral geometry. The crystal packing is stabilized by hydrogen-bonding inter­actions between the N—H groups of the cyclam ligands, the S atoms of the NCS− groups and the Cl− ligands of the anion.
doi:10.1107/S205698901500746X
PMCID: PMC4420107  PMID: 25995875
crystal structure; synchrotron radiation; cyclam; thio­cyanate ligand; trans-III configuration; chromium(III) complex; hydrogen bonding
12.  Crystal structure of cis-di­chlorido­(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4 N)chromium(III) (oxalato-κ2 O 1,O 2)(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4 N)chromium(III) bis(perchlorate) from synchrotron data 
Two CrIII ions (each with site symmetry 2..) in the title compound have a distorted octa­hedral coordination environment with four N atoms of a cyclam ligands and two chloride ions or one oxalate bidentate ligand in a cis position whereby the cyclam ligands adopt a cis-V conformation. The crystal packing is stabilized by extensive hydrogen-bonding inter­actions among the cyclam N–H groups, the Cl ligands, and O atoms of the oxalate and ClO4 − anions.
In the asymmetric unit of the title compound, [CrCl2(C10H24N4)][Cr(C2O4)(C10H24N4)](ClO4)2 (C10H24N4 = 1,4,8,11-tetra­aza­cyclo­tetra­decane, cyclam; C2O4 = oxalate, ox), there are two independent halves of the [CrCl2(cyclam)]+ and [Cr(ox)(cyclam)]+ cations, and one perchlorate anion. In the complex cations, which are completed by application of twofold rotation symmetry, the CrIII ions are coordinated by the four N atoms of a cyclam ligand, and by two chloride ions or one oxalate bidentate ligand in a cis arrangement, displaying an overall distorted octa­hedral coordination environment. The Cr—N(cyclam) bond lengths are in the range of 2.075 (5) to 2.096 (4) Å while the Cr—Cl and Cr—O(ox) bond lengths are 2.3358 (14) and 1.956 (4) Å, respectively. Both cyclam moieties adopt the cis-V conformation. The slightly distorted tetra­hedral ClO4 − anion remains outside the coordination sphere. The supra­molecular architecture includes N—H⋯O and N—H⋯Cl hydrogen bonding between cyclam NH donor groups, O atoms of the oxalate ligand or ClO4 − anions and one Cl ligand as acceptors, leading to a three-dimensional network structure.
doi:10.1107/S2056989016014134
PMCID: PMC5050767  PMID: 27746932
crystal structure; cyclam; synchrotron radiation; chromium(III) complex; chloride ligand; oxalato ligand; cis-V conformation; hydrogen bonding
13.  Crystal structure of N-[(8E)-12-methyl-14-phenyl-10,13,14,16-tetra­aza­tetra­cyclo­[7.7.0.02,7.011,15]hexa­deca-1(16),2,4,6,9,11(15),12-heptaen-8-yl­idene]hydroxyl­amine 1,4-dioxane hemisolvate 
In the title solvate, C19H13N5O·0.5C4H8O2, the main mol­ecule is almost planar (r.m.s. deviation for the non-H atoms = 0.066 Å). The hydroxyl­amine group is disordered over two orientations in a 0.761 (4):0.239 (4) ratio. The complete dioxane solvent mol­ecule is generated by a crystallographic inversion centre. In the crystal, both disorder components of the hydroxyl­amine group form O—H⋯N hydrogen bonds to the same N-atom acceptor, thereby generating [010] chains. The chains encompass [010] channels occupied by the solvent mol­ecules. Aromatic π–π stacking is also observed [shortest centroid–centroid separation = 3.3394 (19) Å].
doi:10.1107/S2056989014027285
PMCID: PMC4384549  PMID: 25878879
crystal strcuture; pyrazino­pyrazoles; oximes; hydrogen bonding; π–π stacking
14.  Crystal structure of 2-[12-methyl-14-phenyl-10,13,14,16-tetra­aza­tetra­cyclo[7.7.0.02,7.011,15]hexa­deca-1(16),2,4,6,9,11(15),12-heptaen-8-yl­idene]propandi­nitrile 
In the title mol­ecule, C22H12N6, the fused tetracyclic core shows a small lengthwise twist as indicated by the dihedral of 2.7 (2)° between the outer rings. In the crystal, mol­ecules stack along the b-axis direction via offset π-stacking [centroid–centroid distances = 3.5282 (13) and 3.5597 (14) Å] with the stacks weakly associated through C—H⋯N hydrogen bonds. The phenyl ring is rotationally disordered over two orientations with an occupancy ratio of 0.516 (4):0.484 (4).
doi:10.1107/S1600536814024167
PMCID: PMC4257392  PMID: 25553023
crystal structure; hepta­ene; propandi­nitrile; pyrazine scaffold compound; fused tetracyclic core
15.  2,3,5-Triphenyl-2H-tetra­zol-3-ium iodide 
The asymmetric unit of the title mol­ecular salt, C19H15N4 +·I−, contains four 2,3,5-triphenyl-2H-tetra­zol-3-ium cations and five iodide anions, with two of the latter lying on crystallographic inversion centres. In each cation, the tetra­zole ring is essentially planar (r.m.s. deviations = 0.004–0.007 Å). The dihedral angles between the tetra­zole ring and its three attached benzene rings in the four independent cations are: 12.9 (4), 67.0 (4), 48.1 (4); 20.8 (4), 51.1 (4), 62.3 (4); 11.4 (4), 52.3 (4), 47.3 (4) and 6.0 (4), 85.7 (4), 43.5 (4)°. A C—H⋯I hydrogen bond and C—H⋯π inter­actions are observed in the crystal.
doi:10.1107/S1600536812033661
PMCID: PMC3435649  PMID: 22969522
16.  Crystal structure of trans-diammine(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4 N)chromium(III) tetra­chlorido­zincate chloride monohydrate from synchrotron data 
Four independent CrIII ions are present in the title structure, each situated on an inversion centre and with a distorted octa­hedral coordination sphere by six N atoms (four from a cyclam ligand in the equatorial plane and two in axial positions). The crystal packing is stabilized by extensive hydrogen-bonding inter­actions between the mol­ecular and ionic moieties.
The asymmetric unit of the title complex salt, [Cr(C10H24N4)(NH3)2][ZnCl4]Cl·H2O, is comprised of four halves of the CrIII complex cations (the counterparts being generated by application of inversion symmetry), two tetra­chlorido­zincate anions, two chloride anions and two water mol­ecules. Each CrIII ion is coordinated by the four N atoms of the cyclam (1,4,8,11-tetra­aza­cyclo­tetra­deca­ne) ligand in the equatorial plane and by two N atoms of ammine ligands in axial positions, displaying an overall distorted octa­hedral coordination environment. The Cr—N(cyclam) bond lengths range from 2.0501 (15) to 2.0615 (15) Å, while the Cr—(NH3) bond lengths range from 2.0976 (13) to 2.1062 (13) Å. The macrocyclic cyclam moieties adopt the trans-III conformation with six- and five-membered chelate rings in chair and gauche conformations. The [ZnCl4]2− anions have a slightly distorted tetra­hedral shape. In the crystal, the Cl− anions link the complex cations, as well as the solvent water mol­ecules, through N—H⋯Cl and O—H⋯Cl hydrogen-bonding inter­actions. The supra­molecular set-up also includes N—H⋯Cl, C—H⋯Cl, N—H⋯O and O—H⋯Cl hydrogen bonding between N—H or C—H groups of cyclam, ammine N—H and water O—H donor groups, and O atoms of the water mol­ecules, Cl− anions or Cl atoms of the [ZnCl4]2− anions as acceptors, leading to a three-dimensional network structure.
doi:10.1107/S205698901600356X
PMCID: PMC4910319  PMID: 27375863
crystal structure; cyclam; ammine ligand; tetra­chlorido­zincate chloride double salt; trans-III conformation; chromium(III) complex
17.  Bis(hydrazin-1-ium) bis­(μ2-pyridazine-3,6-dicarboxyl­ato)bis­(aqua­lithiate) octa­aqua­bis­(μ3-pyridazine-3,6-dicarboxyl­ato)tetra­lithium 
The unit cell of the title compound, (N2H5)2[Li2(C6H2N2O4)2(H2O)2]·[Li4(C6H2N2O4)2(H2O)8], comprises two centrosymmetric complexes, one double negatively charged and one neutral, and two mono-protonated hydrazine cations. The anionic complex molecule is a dimer, built of a pair of symmetry-related pyridazine-3,6-dicarboxyl­ate ligands and a pair of LiI ions, each coordinated by two N,O-chelating sites donated by a ligand mol­ecule and an aqua O atom at the apical position. The penta­coordination around the LiI ions is partway between a trigonal–bipyramidal and a square-pyramidal arrangement. The two carb­oxy­lic acid groups of the ligand are deprotonated and one carboxyl­ate O atom of each group is not involved in the coordination, and this applies to both the anionic and the neutral complex. The neutral complex molecule is also composed of a pair of LiI ions and a pair of ligand mol­ecules related by a centre of symmetry. They form a dimeric core in which the penta­coordination of the LiI ions includes two N,O-bonding groups donated by two ligands and an aqua O atom. The penta­coordination is described as partway between a trigonal–bipyramidal and a square-pyramidal arrangement. The coordinated carboxyl­ate group is bidentate–bridging, forming with an Li(H2O)3 unit a neutral tetra­meric mol­ecule. The coordination of the tetra­coordinated LiI ion shows a slightly distorted tetra­hedral geometry. An extended system of O—H⋯O and N—H⋯O hydrogen bonds contributes to the stability of the crystal structure.
doi:10.1107/S1600536812007192
PMCID: PMC3297271  PMID: 22412461
18.  Coordination of bis­(pyrazol-1-yl)amine to palladium(II): influence of the co-ligands and counter-ions on the mol­ecular and crystal structures1  
The crystal structures for five PdII complexes containing the tridentate ligand bis­[2-(3,5-di­methyl­pyrazol-1-yl)eth­yl]amine (pza) are reported. The co-ligand completing the square-planar coordination of the PdII centre influences the conformation of the pza ligand.
The structures of a series of complexes with general formula n[Pd(pza)X]Y·mH2O (n = 1, 2; X = Cl, Br, I, N3, NCS; Y = NO3, I, N3, [Pd(SCN)4]; m = 0, 0.5, 1) have been determined, where pza is the tridentate ligand bis­[2-(3,5-di­methyl­pyrazol-1-yl)eth­yl]amine, C14H23N5. In all complexes, {bis­[2-(3,5-di­methyl­pyrazol-1-yl-κN 2)eth­yl]amine-κN}chlorido­palladium nitrate, [Pd(pza)Cl]NO3, (1), {bis­[2-(3,5-di­methyl­pyrazol-1-yl-κN 2)eth­yl]amine-κN}bromido­palladium nitrate, [Pd(pza)Br]NO3, (2), {bis­[2-(3,5-di­methyl­pyrazol-1-yl-κN 2)eth­yl]amine-κN}iodido­palladium iodide hemihydrate, [Pd(pza)I]I·0.5H2O, (3), azido{bis­[2-(3,5-di­methyl­pyrazol-1-yl-κN 2)eth­yl]amine-κN}palladium azide monohydrate, [Pd(pza)N3]N3·H2O, (4), and bis­[{bis­[2-(3,5-di­methyl­pyrazol-1-yl-κN 2)eth­yl]amine-κN}(thio­cyanato-κN)palladium] tetra­kis­(thio­cyanato-κS)palladate, [Pd(pza)NCS]2[Pd(SCN)4], (5), the [Pd(pza)X]+ complex cation displays a square-planar coordination geometry, and the pza ligand is twisted, approximating twofold rotation symmetry. Although the pza ligand is found with the same conformation along the series, the dihedral angle between pyrazole rings depends on the co-ligand X. This angle span the range 79.0 (3)–88.6 (1)° for the studied complexes. In (3), two complex cations, two I− anions and one water mol­ecule of crystallization are present in the asymmetric unit. In (5), the central amine group of pza is disordered over two positions [occupancy ratio 0.770 (18):0.230 (18)]. The complex [Pd(SCN)4]2− anion of this compound exhibits inversion symmetry and shows the Pd2+ transition metal cation likewise in a square-planar coordination environment. Compound (5) is also a rare occurrence of a non-polymeric compound in which the pseudohalide ligand NCS− behaves both as thio­cyanate and iso­thio­cyanate, i.e. is coordinating either through the N atom (in the cation) or the S atom (in the anion).
doi:10.1107/S205698901402595X
PMCID: PMC4331852  PMID: 25705441
crystal structure; coordination compounds; bis­[2-(3,5-di­methyl­pyrazol-1-yl)eth­yl]amine (pza) ligand; bis­(pyrazol-1-yl)amine; palladium(II)
19.  Crystal structures of 2,2′-bipyridin-1-ium 1,1,3,3-tetracyano-2-ethoxyprop-2-en-1-ide and bis(2,2′-bipyridin-1-ium) 1,1,3,3-tetracyano-2-(dicyanomethylene)propane-1,3-diide 
In each of the title compounds, the anion shows evidence of extensive electronic delocalization. A combination of N—H⋯N and X—H⋯N hydrogen bonds links the ions in (I) into a ribbon of alternating centrosymmetric (18) and (26) rings, and those in (II) into simple (7) chains of alternating cations and anion with further cations pendent from the chain.
In 2,2′-bipyridin-1-ium 1,1,3,3-tetra­cyano-2-eth­oxy­prop-2-en-1-ide, C10H9N2 +·C9H5N4O−, (I), the ethyl group in the anion is disordered over two sets of atomic sites with occupancies 0.634 (9) and 0.366 (9), and the dihedral angle between the ring planes in the cation is 2.11 (7)°. The two independent C(CN)2 groups in the anion make dihedral angles of 10.60 (6) and 12.44 (4)° with the central propenide unit, and the bond distances in the anion provide evidence for extensive electronic delocalization. In bis­(2,2′-bipyridin-1-ium) 1,1,3,3-tetra­cyano-2-(di­cyano­methyl­ene)propane-1,3-diide [alternative name bis­(2,2′-bipyridin-1-ium) tris­(di­cyano­methyl­ene)methane­diide], 2C10H9N2 +·C10N6 2− (II), the dihedral angles between the ring planes in the two independent cations are 7.7 (2) and 10.92 (17)°. The anion exhibits approximate C 3 symmetry, consistent with extensive electronic delocalization, and the three independent C(CN)2 groups make dihedral angles of 23.8 (2), 27.0 (3) and 27.4 (2)° with the central plane. The ions in (I) are linked by an N—H⋯N hydrogen bond and the resulting ion pairs are linked by two independent C—H⋯N hydrogen bonds, forming a ribbon containing alternating R 4 4(18) and R 4 4(26) rings, where both ring types are centrosymmetric. The ions in (II) are linked by two independent N—H⋯N hydrogen bonds and the resulting ion triplets are linked by a C—H⋯N hydrogen bond, forming a C 2 1(7) chain containing anions and only one type of cation, with the other cation linked to the chain by a further C—H⋯N hydrogen bond.
doi:10.1107/S2056989015007306
PMCID: PMC4420140  PMID: 25995868
crystal structure; bipyridinium cations; polynitrile anions; mol­ecular conformation; hydrogen bonding
20.  catena-Poly[[[(5,5,7,12,12,14-hexa­methyl-1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4 N)nickel(II)]-μ-oxido-[dioxidotungstate(VI)]-μ-oxido] tetra­hydrate] 
In the title compound, {[NiWO4(C16H36N4)]·4H2O}n, the NiII ion lies on an inversion center and is octahedrally coordinated by four N atoms of the tetradentate macrocyclic 5,5,7,12,12,14-hexa­methyl-1,4,8,11-tetra­aza­cyclo­tetra­decane (L) ligand in the equatorial plane and two O atoms of [WO4]2− anions in axial positions. Each [WO4]2− anion bridges two adjacent [NiL]2+ cations, forming a chain along [001]. The chains are further connected via N—H⋯O, O—H⋯O and C—H⋯O hydrogen-bonding inter­actions, generating a three-dimensional structure.
doi:10.1107/S1600536812034538
PMCID: PMC3435596  PMID: 22969469
21.  Crystal structure of the thermochromic bis­(di­ethyl­ammonium) tetra­chlorido­cuprate(II) complex 
The low-temperature structure of bis­(di­ethyl­ammonium) tetra­chlorido­cuprate is reported. The complex exhibits thermochromism and has a two-dimensional hydrogen-bonded network through N—H⋯Cl hydrogen bonds.
In the structure of the title complex salt, (Et2NH2)2[CuCl4], the asymmetric unit consists of four unique di­ethyl­ammonium cations and three unique tetra­chlorido­cuprate anions. Two of the three anions are located with their copper atoms on independent crystallographic twofold axes, while the remaining tetra­chlorido­cuprate is located at a general position of the ortho­rhom­bic space group P21212. Two of the three Cu atoms adopt a distorted square-planar/disphenoidal geometry and the third Cu atom has a regular square-planar coordination environment. The di­ethyl­ammonium cations form an extensive hydrogen-bonded network through N—H⋯Cl inter­actions with the tetra­chlorido­cuprate anions, resulting in a two-dimensional sheet-like hydrogen-bonded network parallel to the ab direction. The complex was observed to undergo a color shift from deep green at room temperature to pale yellow at temperatures above 328 K.
doi:10.1107/S2056989015023348
PMCID: PMC4704760  PMID: 26870581
crystal structure; four-coordinate copper(II) complex; thermochromism
22.  Bis(2-amino-5-benzyl-3-eth­oxy­carbonyl-4,5,6,7-tetra­hydro­thieno[3,2-c]pyridin-5-ium) bis­(4-meth­oxy­phen­yl)di­phos­phon­ate 
The asymmetric unit of the title salt, 2C17H21N2O2S+·C14H14O7P2 2−, contains half of a centrosymmetric bis­(4-meth­oxy­phen­yl)di­phospho­nate anion and one 2-amino-5-benzyl-3-eth­oxy­carbonyl-4,5,6,7-tetra­hydro­thieno[3,2-c]pyri­din-5-ium cation. In the anion, the O atoms of the di­phospho­nate group are disordered over two positions with equal occupancies. In the cation, the ethyl group is disordered over two orientations with a refined occupancy ratio of 0.753 (5):0.247 (5), and the tetra­hydro­pyridinium ring adopts a distorted half-chair conformation. In the crystal, the ions are linked by C—H⋯O, N—H⋯O and C—H⋯S hydrogen bonds into a three-dimensional network.
doi:10.1107/S1600536814003766
PMCID: PMC3998403  PMID: 24765038
23.  Crystal structures of three anhydrous salts of the Lewis base 1,8-di­aza­bicyclo­[5.4.0]undec-7-ene (DBU) with the ring-substituted benzoic acid analogues 4-amino­benzoic acid, 3,5-di­nitro­benzoic acid and 3,5-di­nitro­salicylic acid 
The anhydrous morpholinium salts of 1,8-di­aza­bicyclo­[5.4.0]undec-7-ene (DBU) with 4-amino­benzoic acid, 3,5-di­nitro­benzoic acid and 3,5-di­nitro­salicylic acid, provide one example of a three-dimensional hydrogen-bonded network polymer and two of weakly inter-associated hydrogen-bonded cation–anion units.
The anhydrous salts of the Lewis base 1,8-di­aza­bicyclo­[5.4.0]undec-7-ene (DBU) with 4-amino­benzoic acid [1-aza-8-azoniabi­cyclo­[5.4.0]undec-7-ene 4-amino­benzoate, C9H17N2 +·C7H6NO2 − (I)], 3,5-di­nitro­benzoic acid [1-aza-8-azoniabi­cyclo­[5.4.0]undec-7-ene 3,5-di­nitro­benzoate, C9H17N2 +·C7H3N2O6 −, (II)] and 3,5-di­nitro­salicylic acid (DNSA) [1-aza-8-azoniabi­cyclo­[5.4.0]undec-7-ene 2-hy­droxy-3,5-di­nitro­benzoate, C9H17N2 +·C7H3N2O7 −, (III)] have been determined and their hydrogen-bonded structures are described. In both (II) and (III), the DBU cations have a common disorder in three of the C atoms of the six-membered ring moieties [site-occupancy factors (SOF) = 0.735 (3)/0.265 (3) and 0.686 (4)/0.314 (4), respectively], while in (III), there is additional rotational disorder in the DNSA anion, giving two sites (SOF = 0.72/0.28, values fixed) for the phenol group. In the crystals of (I) and (III), the cation–anion pairs are linked through a primary N—H⋯Ocarbox­yl hydrogen bond [2.665 (2) and 2.869 (3) Å, respectively]. In (II), the ion pairs are linked through an asymmetric three-centre R 1 2(4), N—H⋯O,O′ chelate association. In (I), structure extension is through amine N—H⋯Ocarbox­yl hydrogen bonds between the PABA anions, giving a three-dimensional structure. The crystal structures of (II) and (III) are very similar, the cation–anion pairs being associated only through weak C—H⋯O hydrogen bonds, giving in both overall two-dimensional layered structures lying parallel to (001). No π–π ring associations are present in any of the structures.
doi:10.1107/S205698901600267X
PMCID: PMC4778835  PMID: 27006813
crystal structure; 1,8-di­aza­bicyclo­[5.4.0]undec-7-ene; BDU; benzoate salts; hydrogen bonding
24.  1-(Ferrocen-1-ylmeth­yl)-3-methyl­imidazol-3-ium iodide 
The structure of the title compound, [Fe(C5H5)(C10H12N2)]I, consists of a 1-(ferrocen-1-ylmeth­yl)-3-methyl­imidazolium cation which is counter-balanced by an iodide anion. The cyclo­penta­dienyl (Cp) rings of the ferrocene unit have a slightly staggered conformation skewed from an ideal eclipsed conformation by an angle of 3.5 (6)°. The inter­planar angle between the Cp and the imidazole ring is 67.94 (2)°.
doi:10.1107/S1600536812045400
PMCID: PMC3588731  PMID: 23468696
25.  Crystal structure of tetra­methyl­tetra­thia­fulvalenium (1S)-camphor-10-sulfonate dihydrate 
In this salt, two types of TMTTF units are present as TMTTF. + radical cations which form one-dimensional stacks in which they are associated two by two, forming dimers with short S⋯S contacts. The S-camphSO3 anions also form stacks and are connected with each other via O—H⋯O hydrogen bonds. The columns of cations and anions are connected through C—H⋯O hydrogen bonds.
Electro-oxidation of tetra­methyl­tetra­thia­fulvalene (TMTTF) in the presence of the chiral anion (1S)-camphor-10-sulfonate (S-camphSO3 −) in tetra­hydro­furan/water medium afforded a 1/1 salt formulated as TMTTF·S-camphSO3·2H2O or 2-(4,5-dimethyl-1,3-di­thiol-2-yl­idene)-4,5-dimethyl-1,3-di­thiole radical ion (1+) [(1S)-7,7-dimethyl-2-oxobi­cyclo­[2.2.1]heptan-1-yl]methane­sulfonate dihydrate, C10H12S4 +·C10H15O4S−·2H2O. In this salt, two independent TMTTF units are present but, in both cases, the observed bond lengths and especially the central C=C distance [1.392 (6) and 1.378 (6) Å] are in agreement with a complete oxidation of TMTTF which is thus present as TMTTF. + radical cations. These cations form one-dimensional stacks in which they are associated two by two, forming dimers with short [3.472 (1) to 3.554 (2) Å] S⋯S contacts. The two S-camphSO3 anions present also form stacks and are connected with each other via the water mol­ecules with many O—H⋯O hydrogen bonds ranging from 1.86 (3) to 2.15 (4) Å; the O—H⋯O hydrogen-bonding network can be described as being constituted of C 2 2(6) chains bearing R 3 3(11) lateral rings. On the other hand, the columns of cations and anions are connected through C—H⋯O hydrogen bonds, forming a system expanding in three directions; finally, the result is a three-dimensional network of O—H⋯O and C—H⋯O hydrogen bonds.
doi:10.1107/S2056989015010294
PMCID: PMC4518967  PMID: 26279858
crystal structure; tetra­thia­fulvalene-based materials; chirality; hydrogen bonding

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