Racemic cis-bis-[bis-(pyrimidin-2-yl)amine-κN]bis(dicyanamido-κN1)iron(II) dihydrate: synthesis, crystal structure and Hirshfeld surface analysis.

The title compound, [Fe(C2N3)2(C8H7N5)2]·2H2O, has been synthesized solvothermally and characterized by single-crystal X-ray diffraction. The octa-hedral iron coordination polyhedron contains two di(pyrimidin-2-yl)amine ligands coordinated in a bidentate fashion, and two monodentate dicyanimido ligands, each coordinated via a terminal N atom, with the latter in a cis orientation. The ligand configuration about the iron atom is chiral, although the compound crystallizes as a racemic mixture: the Fe-N distances (> 2.07 Å) are characteristic of high-spin iron(II). In the crystal, an extensive series of N-H⋯N, O-H⋯N and O-H⋯O hydrogen bonds links the independent mol-ecular components into a three-dimensional framework. The H atoms of both water mol-ecules are disordered. The structure also features some π-π and anion-π inter-actions. The inter-molecular inter-actions were investigated by Hirshfeld surface analysis and two-dimensional fingerprint plots. Comparisons are made with some related compounds.

Concomitant dimorphism in poly[di-µ-azido-(5,5'-dimethyl-2,2'-bipyridine)iron(II)].

The title metal-organic polymer, catena-poly[[(5,5'-dimethyl-2,2'-bipyridine-κ2N,N')iron(II)]-di-µ-azido-κ2N1:N3-[(5,5'-dimethyl-2,2'-bipyridine-κ2N,N')iron(II)]-di-µ-azido-κ2N1:N1], [Fe(N3)2(C12H12N2)]n, features alternating µ-1,1 (end-on mode of coordination) and µ-1,3 (end-to-end mode of coordination) double azide bridges, forming chains running in the [100] direction. The octahedral coordination geometry around the FeII centre is completed by a bidentate 5,5'-dimethyl-2,2'-bipyridine ligand. Two polymorphs for this compound were obtained from the crude reaction product, the first in the space group P-1 and the other in P21/c. The molecular and crystal structures are very similar for both forms, the main difference being that the eight-membered Fe(µ-1,3-N3)2Fe metallacycle formed with end-to-end azide ligands has a nearly flat conformation in the triclinic form and a chair conformation in the monoclinic form. In spite of this geometric difference, both forms have the same density, the same packing index and similar arrangements of the one-dimensional chains in the crystal. As a consequence, they also share very similar Hirshfeld surfaces and fingerprint plots. However, a density functional theory (DFT) computational study showed that the monoclinic form is more stable than the triclinic form by ca 30.5 kJ mol-1.

A rare example of a double metamagnetic transition leading to 2D and 3D long-range order in the two-dimensional pyrazine- and azido-bridged cobalt(II) compound [Co(pyz)(N3)2].

The synthesis, characterization, crystal structure and detailed magnetic properties of a pyrazine (pyz) and azido (N3) bridged cobalt(II) compound of formula [Co(N3)2(pyz)] (1) are reported. Compound 1 shows a layered structure formed by Co(II) chains with double µ-N3(κN1,N1) bridges that are further connected by µ-(pyrazine-κN1,N4) bridges. The layers present weak van der Waals interactions between azido terminal groups. The magnetic properties show the presence of a metamagnetic behaviour in 1 with two critical fields of 200 and 400 mT at low temperatures. AC magnetic measurements show the presence of a long-range 2D ferromagnetic order at Tc ≈ 8.0-7.0 K for dc fields above 200 mT and a long-range 3D ferromagnetic order at Tc ≈ 4.5 K for dc fields above 400 mT.

trans-Bis(2,2'-di-pyridyl-amine-κ2 N,N')-bis-(1,1,3,3-tetra-cyano-2-eth-oxy-propenido-κN)copper(II).

The title compound, [Cu(C9H5N4O)2(C10H9N3)2], was synthesized solvothermally. The complex exhibits a distorted octa-hedral coordination geometry. The CuII atom is located on an inversion centre. The distorted octahedral CuN6 coordination sphere is composed of bidentate 2,2'-dipyrid-ylamine in the equatorial sites while the axial sites are occupied by 1,1,3,3-tetra-cyano-2-eth-oxy-propenide ligands. In the crystal, N-H⋯N hydrogen bonding results in chains parallel to [010].

catena-Poly[[bis-(quinolin-8-amine-κ2 N,N')cadmium(II)]-µ-cyanido-κ2 N:C-[dicyanidonickel(II)]-µ-cyanido-κ2 C:N].

In the title compound, [CdNi(C9H8N2)2(CN)4] n , the Cd and Ni atoms both lie on centres of inversion in space group P21/c. The Cd atom is coordinated by two bidentate quinolin-8-amine ligands and by the N atoms of two cyano ligands, while the square planar Ni atom is coordinated by the C atoms of four cyano ligands. These units form a one-dimensional coordination polymer containing an (-NC-Ni-CN-Cd-) n backbone, and the coordination polymer chains are linked into a three-dimensional array by a combination of N-H⋯N and C-H⋯N hydrogen bonds, augmented by a π-π stacking inter-action.

Synthesis, crystal structure and Hirshfeld surface analysis of bis-{2-[(pyridin-2-yl)amino]-pyridinium} tetra-cyano-nickelate(II).

In the title mol-ecular salt, (C10H10N3)2[Ni(CN)4], the dihedral angle between the pyridine rings in the cation is 1.92 (13)° and the complete anion is generated by a crystallographic centre of symmetry. An intra-molecular N-H⋯N hydrogen bond occurs in the cation, which closes an S(6) ring. In the crystal, the components are linked by N-H⋯N and weak C-H⋯N hydrogen bonds, which generate chains propagating in the [101] direction. Weak aromatic π-π stacking inter-actions are also observed. A Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contact types in the crystal packing are N⋯H/H⋯N, C⋯H/H⋯C and H⋯H with contributions of 37.2, 28.3 and 21.9%, respectively.

fac-Tri-aqua-(1,10-phenanthroline-κ2 N,N')(sulfato-κO)cobalt(II): crystal structure, Hirshfeld surface analysis and computational study.

The CoII atom in the title complex, [Co(SO4)(C12H8N2)(H2O)3] (or C12H14CoN2O7S), is octa-hedrally coordinated within a cis-N2O4 donor set defined by the chelating N-donors of the 1,10-phenanthroline ligand, sulfate-O and three aqua-O atoms, the latter occupying an octa-hedral face. In the crystal, supra-molecular layers lying parallel to (110) are sustained by aqua-O-H⋯O(sulfate) hydrogen bonding. The layers stack along the c-axis direction with the closest directional inter-action between them being a weak phenanthroline-C-H⋯O(sulfate) contact. There are four significant types of contact contributing to the calculated Hirshfeld surface: at 44.5%, the major contribution comes from O-H⋯O contacts followed by H⋯H (28.6%), H⋯C/C⋯H (19.5%) and C⋯C (5.7%) contacts. The dominance of the electrostatic potential force in the mol-ecular packing is also evident in the calculated energy frameworks. The title complex is isostructural with its manganese, zinc and cadmium containing analogues and isomeric with its mer-tri-aqua analogue.

Solid-state 1D → 3D transformation of polynitrile-based coordination polymers by dehydration reaction.

In crystal structures of two chain coordination polymers [M(tcnopr3OH)2(H2O)2] (M = NiII and CoII; tcnopr3OH- = [(NC)2CC(O(CH2)3OH)C(CN)2]-) based on a N,O or N,N'-bridge polynitrile ligand, the parallel chains are connected via, respectively, C[triple bond, length as m-dash]NH-O and O-HO hydrogen bonds between uncoordinated functional groups of the ligand and coordinated water molecules. Upon heating, both solids undergo dehydration accompanied by degradation of their single crystals. Powder X-ray diffraction showed that non-isostructural triclinic single crystals transformed to isostructural monoclinic compounds. The solid-state reaction yielded 3D coordination polymers [M(tcnopr3OH)2] (M = NiII and CoII) based on a N,N',O-connected tcnopr3OH-. Although previously tens of complexes based on tcnopr3OH and similar anions were synthesized and X-ray characterized, none of these contain a tridentate polynitrile ligand. Thus, this study provides evidence that solid-state reactions allow obtaining novel coordination modes of polynitrile ligands. The possible pathways for the transformation of H-bonded networks to 3D coordination polymers are discussed on the basis of the topological approach. Applicability of the topological approach to predict possible networks of solid-state reaction products based on the crystal structures of initial compounds is demonstrated.

Bis[tris-(pyridin-2-yl)amine]-iron(II) tris-(di-cyano-methyl-idene)methane-diide.

In the title compound, [Fe{(C5H4N)3N}2][C{C(CN)2}3], both ions lie across centres of inversion, with the anion being statistically disordered over two sets of atomic sites having equal occupancy. The cation and anion have approximate and 32 symmetry, respectively, and the Fe-N bond lengths indicate low-spin FeII. A combination of two-centre C-H⋯N and three-centre C-H⋯(N)2 hydrogen bonds link the ions into complex sheets. Several low-occupancy water mol-ecules are present, whose H atoms could not be located: accordingly, the reflection data were subjected to the SQUEEZE procedure [Spek (2015 ▸). Acta Cryst. C71, 9-18].

Crystal structure and Hirshfeld surface analysis of tris-(2,2'-bi-pyridine)-nickel(II) bis-(1,1,3,3-tetra-cyano-2-eth-oxy-propenide) dihydrate.

The title compound, [Ni(C10H8N2)3](C9H5N4O)2·2H2O, crystallizes as a racemic mixture in the monoclinic space group C2/c. In the crystal, the 1,1,3,3-tetracyano-2-ethoxypropenide anions and the water molecules are linked by O-H⋯N hydrogen bonds, forming chains running along the [010] direction. The bpy ligands of the cation are linked to the chain via C-H⋯π(cation) inter-actions involving the CH3 group. The inter-molecular inter-actions were investigated by Hirshfeld surface analysis and two-dimensional fingerprint plots.

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 FeII 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.

Crystal structure of tris-(2,2'-bi-pyridine)-cobalt(II) bis-(1,1,3,3-tetra-cyano-2-eth-oxy-propenide).

In the title compound, [Co(C10H8N2)3](C9H5N4O)2, the tris-(2,2'-bi-pyridine)-cobalt(II) dication lies across a twofold rotation axes in the space group C2/c. The N atoms of the three bi-pyridine ligands form a distorted octa-hedron around the cobalt ion. All the N atoms of the polynitrile 1,1,3,3-tetra-cyano-2-eth-oxy-propenide anions participate in C-H⋯N hydrogen bonds ensuring crystal cohesion and forming a three-dimensional structure. The structure is further stabilized by C-H⋯π(cation) and anion⋯π(cation) inter-actions.

Six tris-(bipyrid-yl)iron(II) complexes with 2-substituted 1,1,3,3-tetra-cyano-propenide, perchlorate and tetra-fluorido-borate anions; order versus disorder, hydrogen bonding and C-N⋯π inter-actions.

Structures are reported for six closely related salts of tris-(bipyrid-yl)iron(II) cations, namely tris-(2,2'-bi-pyridine)-iron(II) bis-(1,1,3,3-tetra-cyano-2-meth-oxy-propenide) 0.776-hydrate, [Fe(C10H8N2)3](C8H3N4O)2.0.776H2O, (I), tris-(2,2'-bi-pyridine)-iron(II) 1,1,3,3-tetra-cyano-2-(propyl-sulfan-yl)propenide perchlor-ate, [Fe(C10H8N2)3](C10H7N4S)(ClO4), (II), tris-(5,5'-dimethyl-2,2'-bi-pyridine)-iron(II) 1,1,3,3-tetra-cyano-2-meth-oxy-propenide tetra-fluorido-borate ethanol 0.926-solvate, [Fe(C12H12N2)3](C8H3N4O)(BF4).0.926C2H2O, (III), tris-(5,5'-dimethyl-2,2'-bi-pyridine)-iron(II) 1,1,3,3-tetra-cyano-2-eth-oxy-propenide tetra-fluorido-borate, [Fe(C12H12N2)3](C9H5N4O)(BF4), (IV), tris-(5,5'-dimethyl-2,2'-bi-pyridine)-iron(II) 1,1,3,3-tetra-cyano-2-(ethyl-sufanyl)propenide tetra-fluorido-borate, [Fe(C12H12N2)3](C9H5N4S)(BF4), (V), and tris-(5,5'-dimethyl-2,2'-bi-pyri-dine)-iron(II) 1,1,3,3-tetra-cyano-2-prop-oxypropenide tetra-fluorido-borate, [Fe(C12H12N2)3](C10H7N4O)(BF4), (VI). In compound (I), one of the anions is disordered over two sets of atomic sites with equal occupancies while, in the second anion, just one of the C(CN)2 units is disordered, again over two sets of atomic sites with equal occupancies: the anionic components are linked by multiple C-H⋯N hydrogen bonds to form a three-dimensional framework. In compound (II), the polynitrile anion is disordered over two sets of atomic sites with occupancies in the approximate ratio 3:1, while the perchlorate anion is disordered over three sets of atomic sites: there are C-N⋯π inter-actions between the cations and the polynitrile anion. The polynitrile anion in compound (III) is fully ordered, but the tetra-fluorido-borate anion is disordered over two sets of atomic sites with occupancies 0.671 (4) and 0.329 (4): the cations and the tetra-fluorido-borate anions are linked by C-H⋯F inter-actions to form an inter-rupted chain. Compounds (IV) and (V) are isostructural and all of the ionic components are fully ordered in both of them: the cations and tetra-fluorido-borate anions are linked into C 2 2(12) chains. The polynitrile anion in compound (VI) is disordered over two sets of atomic sites with approximately equal occupancies, and here the chains formed by the cations and the tetra-fluorido-borate anions are of the C 2 2(13) type.

Crystal structure of fac-bis-[bis-(pyridin-2-yl)methan-amine]-iron(II) 1,1,3,3-tetra-cyano-2-(di-cyano-methyl-idene)propane-1,3-diide, [Fe(dipa)2](tcpd).

In the title compound, [Fe(C11H11N3)2](C10N6), the FeII cation is coordinated by two bis(pyridin-2-yl)methanamine (dipa) ligands and has crystallographic twofold symmetry. There are deviations from ideal octa-hedral geometry due to the steric requirements of the ligands. The polynitrile 1,1,3,3-tetra-cyano-2-(di-cyano-methylid-ene)propane-1,3-diide (tcpd2-) dianion is disordered about an inversion center and is not coordinated to the Fe atom. The anion is not planar but has a propeller shape. In the crystal, weak N-H⋯N inter-actions between the amine H atoms of the dipa ligands and two nitrile groups of the anion form an alternating chain of cations and anions related by the C-centering of the unit cell.

Redetermination of the crystal structure of bis-(tri-2-pyridyl-amine)-iron(II) bis-(perchlorate), and a new refinement of the isotypic nickel(II) analogue: treatment of the perchlorate anion disorder.

The redetermination of the structure of the title compound, [Fe(C15H12N4)2](ClO4)2, (I), confirms the structure previously reported [Kucharski et al. (1978a ▸). Aust. J. Chem. 31, 53-56], but models the perchlorate over four sets of atomic sites, rather than using just one set of sites as in the original report. The supra-molecular assembly, not reported previously, takes the form of a complex three-dimensional framework built from C-H⋯O hydrogen bonds. The isotypic nickel(II) analogue, [Ni(C15H12N4)2](ClO4)2, (III), has been refined using the original data set [Wang et al. (2011 ▸). Acta Cryst. E67, m78], again using a four-component disorder model for the anion, rather than a two-component model as in the original report, leading to more satisfactory Cl-O distances and O-Cl-O angles.

Three zinc(II) and cadmium(II) complexes containing 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole and polynitrile ligands: synthesis, molecular and supramolecular structures, and photoluminescence properties.

Three photoluminescent complexes containing either ZnII or CdII have been synthesized and their structures determined. Bis[4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole-κ2N1,N5]bis(dicyanamido-κN1)zinc(II), [Zn(C12H10N6)2(C2N3)2], (I), bis[4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole-κ2N1,N5]bis(dicyanamido-κN1)cadmium(II), [Cd(C12H10N6)2(C2N3)2], (II), and bis[4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole-κ2N1,N5]bis(tricyanomethanido-κN1)cadmium(II), [Cd(C12H10N6)2(C4N3)2], (III), all crystallize in the space group P-1, with the metal centres lying on centres of inversion, but neither analogues (I) and (II) nor CdII complexes (II) and (III) are isomorphous. A combination of N-H...N and C-H...N hydrogen bonds and π-π stacking interactions generates three-dimensional framework structures in (I) and (II), and a sheet structure in (III). The photoluminescence spectra of (I)-(III) indicate that the energies of the π-π* transitions in the coordinated triazole ligand are modified by minor changes of the ligand geometry associated with coordination to the metal centres.

Crystal structure of meso-di-µ-chlorido-bis-[bis-(2,2'-bi-pyridine)-cadmium] bis-(1,1,3,3-tetra-cyano-2-ethoxy-propenide) 0.81-hydrate.

The hydrated title salt, [Cd2Cl2(C10H8N2)4](C9H5N4O)2·0.81H2O, was obtained from the hydro-thermal reaction between 2,2'-bi-pyridine, cadmium(II) chloride and potassium 1,1,3,3-tetra-cyano-2-eth-oxy-propenide. The binuclear cation lies across a centre of inversion in the space group P21/c, with the other components in general positions. The cation has approximate, but non-crystallographic 2/m symmetry and each of the CdII atoms is a stereogenic centre, one having the Δ configuration and the other the Λ configuration. In the anion, one of the C(CN)2 units is disordered over two sets of atomic sites having occupancies 0.75 (2) and 0.25 (2). The cations are linked by two independent C-H⋯Cl hydrogen bonds to form a sheet of R22(14) and R42(24) rings.

Crystal structure of [tris-(4,4'-bi-pyridine)]-diium bis-(1,1,3,3-tetra-cyano-2-eth-oxy-propenide) trihydrate.

The title hydrated salt, C30H26N62+·2C9H5N4O-·3H2O, was obtained as an unexpected product from the hydro-thermal reaction between potassium 1,1,3,3-tetra-cyano-2-eth-oxy-propenide, 4,4'-bi-pyridine and iron(II) sulfate hepta-hydrate. The cation lies across a twofold rotation axis in the space group I2/a with the other components all in general positions. In the cation, the H atom linking the pyridine units is disordered over two adjacent sites having occupancies of 0.66 (4) and 0.36 (4), i.e. as N-H⋯N and N⋯H-N. The water mol-ecules of crystallization are each disordered over two sets of atomic sites, having occupancies of 0.522 (6) and 0.478 (6) for one, and 0.34 (3) and 0.16 (3) for the other, and it was not possible to reliably locate the H atoms associated with these partial-occupancy sites. In the crystal, four independent C-H⋯N hydrogen bonds link the ionic components into a three-dimensional network.

Crystal structure of bis-(azido-κN)bis-(quinolin-8-amine-κ2N,N')iron(II).

The search for new mol-ecular materials with inter-esting magnetic properties using the pseudohalide azide ion and quinolin-8-amine (aqin, C9H8N2) as a chelating ligand, led to the synthesis and structure determination of the title complex, [Fe(N3)2(C9H8N2)2]. The complex shows an octa-hedral geometry, with the FeII atom surrounded by six N atoms; the two N3- anions coordinate in a cis configuration, while the remaining N atoms originate from the two quinolin-8-amine ligands with the quinoline N atoms lying on opposite sides of the Fe atom. The crystal packing is dominated by layers of hydro-philic and aromatic regions parallel to the ac plane, stabilized by a two-dimensional hydrogen-bonded network and π-π stacking.

Bis{bis-(azido-κN)bis-[bis-(pyridin-2-yl-κN)amine]cobalt(III)} sulfate dihydrate.

The search for new mol-ecular materials with inter-esting magnetic properties, using the pseudohalide azide ion and di-2-pyridyl-amine (dpa, C10H9N3) as a chelating ligand, led to the synthesis and structure determination of the title compound, [Co(N3)2(dpa)2]2SO4·2H2O. The crystal structure comprises discrete [Co(dpa)2(N3)2](+) cations, sulfate anions, as well as H2O solvent mol-ecules. The Co(III) cations display a slightly distorted octa-hedral coordination sphere defined by two N atoms from azide anions and four N atoms from the pyridyl rings of two dpa ligands. In the crystal, extensive C-H⋯O, N-H⋯O, and O-H⋯O inter-actions result in supra-molecular sheets that lie parallel to the ab plane. The sheets are further linked through O-H⋯N inter-actions between the water mol-ecules of one sheet and azide anions of another sheet, forming a supra-molecular framework.