Explaining How α-Hydroxamate Ligands Control the Formation of Cu(II)-, Ni(II)-, and Zn(II)-Containing Metallacrowns.

Four different crystal structures for quinolinehydroxamic acid (QuinHA) and picolinehydroxamic acid (PicHA) MCs with Cu(II) and Ni(II), and solution studies on the formation of Cu(II), Ni(II), and Zn(II) MC complexes with QuinHA, PicHA, and pyrazylohydroxamic acid (PyzHA) are described. In polynuclear complex 1, [Cu5(QuinHA-2H)4(NO3)(DMSO)4](NO3), the metallamacrocyclic cavity is formed by four Cu(II) ions and four doubly deprotonated hydroximate ligands, and the center of the cavity is occupied by the fifth Cu(II) ion coordinated by four hydroximate oxygen atoms. The complex 2, [Cu10(PicHA-2H)8(H2O)4(ClO4)3](ClO4)·4H2O, exhibits a dimeric structure based on two pentanuclear collapsed 12-MC-4 Cu4(PicHA-2H)4 fragments united by two chiral capping Cu(II) ions exo-coordinated to the peripheral vacant (O,O') chelating units of each tetranuclear collapsed MC moiety. 3, [CaNi5(QuinHA-2H)5(H2O)2(Py)10](NO3)2, and 4, [CaNi5(PicHA-2H)5(DMF)2(Py)8](NO3)2, are planar 15-membered rings consisting of a PicHA or QuinHA ligand, respectively. To understand fully the correlation between species isolated in the solid state and those presented in solution, the solution equilibria were investigated, showing the dependence of the MCs topologies and stability constants (log ß) on the ligand structure and metal ion.

2-[(Pyridin-2-yl)amino]-pyridinium 2,4,6-tri-nitro-phenolate.

In the cation of the title salt, C10H10N3 (+)·C6H2N3O7 (-), the pyridine and pyridinium rings are linked by an intra-molecular N-H⋯N hydrogen bond and are approximately coplanar, with a dihedral angle between their planes of 4.24 (6)°. In the crystal, the cations and anions are linked through N-H⋯O hydrogen bonds, forming supra-molecular chains propagating along the c-axis direction. π-π stacking is observed between neighbouring chains, the centroid-centroid distances being 3.7638 (11) (between pyridinium rings) and 3.5331 (11) Š(between benzene rings).

Crystal structure and Hirshfeld surface analysis of 2-bromo-ethyl-ammonium bromide - a possible side product upon synthesis of hybrid perovskites.

This study presents the synthesis, characterization and Hirshfeld surface analysis of a small organic ammonium salt, C2H7BrN+·Br-. Small cations like the one in the title compound are considered promising components of hybrid perovskites, crucial for optoelectronic and photovoltaic applications. While the incorporation of this organic cation into various hybrid perovskite structures has been explored, its halide salt counterpart remains largely uninvestigated. The obtained structural results are valuable for the synthesis and phase analysis of hybrid perovskites. The title compound crystallizes in the solvent-free form in the centrosymmetric monoclinic space group P21/c, featuring one organic cation and one bromide anion in its asymmetric unit, with a torsion angle of -64.8 (2)° between the ammonium group and the bromine substituent, positioned in a gauche conformation. The crystal packing is predominantly governed by Br⋯H inter-actions, which constitute 62.6% of the overall close atom contacts.

Coordination diversity in mono- and oligonuclear copper(II) complexes of pyridine-2-hydroxamic and pyridine-2,6-dihydroxamic acids.

Solution and solid state studies on Cu(II) complexes of pyridine-2-hydroxamic acid (HPicHA) and pyridine-2,6-dihydroxamic acid (H2PyDHA) were carried out. The use of methanol/water solvent allowed us to investigate the Cu(II)-HPicHA equilibria under homogeneous conditions between pH 1 and 11. In agreement with ESI-MS indication, the potentiometric data fitted very well with the model usually reported for copper(II) complexes of α-aminohydroxamate complexes ([CuL](+), [Cu5(LH-1)4](2+), [CuL2], [CuL2H-1](-)), however with much higher stability of the 12-MC-4 species. A series of copper(II) complexes has been isolated in the solid state and characterized by a variety of spectroscopic methods, X-ray structure analysis, and magnetic susceptibility measurements. The ligands show the tendency to form bi- and trinuclear species with copper(II) ions due to the {(N,N'); (O,O')} bis-(bidentate) chelating-and-bridging mode involving (O,O')-hydroxamate chelate formation combined with (N,N') chelating with participation of the pyridine and hydroxamic nitrogen atoms, so that the hydroxamate groups play a µ2-(N,O)-bridging role. Molecular and crystal structures of three synthesized complexes [Cu3(PicHA-H)2(dipy)2](ClO4)2·4/3DMSO·2/3H2O (1), [Cu2(PyDHA)(dipy)2(ClO4)2]·DMF·H2O (4), and [Cu3(PyDHA-2H)(tmeda)3](ClO4)2 (5) (dipy, 2,2'-dipyridyl; tmeda, N,N,N',N'-tetramethyl-1,2-diaminoethane) have been determined by single crystal X-ray analysis. In 1, two trans-situated doubly deprotonated hydroxamic ligands play a {(O,O')(N,N')}-(bis)bidentate-bridging function forming bridges between the medial, Cu(2) (CuN4), and the terminal, Cu(1) and Cu(3) (CuN2O2), copper(II) ions; the chelating dipy ligands are coordinated to the latter. In 4, the ligand is coordinated in a classical (O,O')-hydroxamate chelating mode with the help of two separate hydroxamic groups while the central tridentate donor compartment remains vacant. In 5, the hydroxamate ligand is coordinated by the {(O,O');(N,N',N″);(O″,O"')}-tridentate-(bis)bidentate mode, bridging three copper(II) ions, while the chelating tmeda ligands are coordinated to all three copper(II) ions. Magnetic susceptibility measurements (1.7-300 K) of powdered samples of the trinuclear complexes 1 and 5 revealed strong antiferromagnetic coupling between the copper(II) ions mediated by the hydroxamate bridges.

cis-Dichlorido(dimethyl sulfoxide-κS)(N,N,N',N'-tetra-methyl-guanidine-κN'')platinum(II).

In the title compound, cis-[PtCl(2)(C(5)H(13)N(3))(C(2)H(6)OS)], the four-coordinate Pt(II) atom is bonded to one N atom of the N,N,N',N'-tetra-methyl-guanidine ligand, one dimethyl sulfoxide S atom and two chloride ligands, forming a cis-square-planar geometry. The bond lengths and angles of the N-Pt-Cl functionality are typical for imine dichloridoplatinum(II) complexes. The H atom of the imino group is oriented towards the O atom of the sulfoxide group of a neighboring mol-ecule and forms an N-H⋯O hydrogen bond.

Pyridinium bis-(pyridine-κN)tetra-kis-(thio-cyanato-κN)ferrate(III)-pyrazine-2-carbo-nitrile-pyridine (1/4/1).

In the title compound, (C5H6N)[Fe(NCS)4(C5H5N)2]·4C5H3N3·C5H5N, the Fe(III) ion is located on an inversion centre and is six-coordinated by four N atoms of the thio-cyanate ligands and two pyridine N atoms in a trans arrangement, forming a slightly distorted octa-hedral geometry. A half-occupied H atom attached to a pyridinium cation forms an N-H⋯N hydrogen bond with a centrosymmetrically-related pyridine unit. Four pyrazine-2-carbo-nitrile mol-ecules crystallize per complex anion. In the crystal, π-π stacking inter-actions are present [centroid-centroid distances = 3.6220 (9), 3.6930 (9), 3.5532 (9), 3.5803 (9) and 3.5458 (8) Å].

Crystal structure and Hirshfeld surface analysis of bis-(3-aminopyrazole-κN1)bis-(3-aminopyrazole-κN2)bis-(nitrato-κO)copper(II).

In the crystal structure of the title compound, [Cu(NO3)2(C3H5N3)4], the CuII atom is situated on an inversion center (Wyckoff position 2c of space group P21/n) and shows an octa-hedral [N4O2] coordination environment. The axial positions are occupied by O atoms of nitrate anions, while the equatorial positions are taken up by the N atoms of four 3-amino-pyrazole ligands. As a result of the tautomerism of the latter, two coordinate with the N1-atom of 3-amino-pyrazole while the other two with the N2-atom. The presence of pyrrole-like N-H groups and amine substituents as donor groups leads to numerous intra- and inter-molecular hydrogen-bonding inter-actions, which were qu-anti-fied by Hirshfeld surface analysis.

Crystal structure and Hirshfeld surface analysis of poly[[tetra-aqua-(µ-1,3,4,7,8,10,12,13,16,17,19,22-dodeca-aza-tetra-cyclo-[8.8.4.13,17.18,12]tetra-cosane-5,6,14,15,20,21-hexaonato)iron(IV)dilithium] tetra-hydrate].

The title compound, [FeLi2(C12H12N12O6)(H2O)4]·4H2O, consists of iron complex anions, lithium cations and water mol-ecules. The complex anion shows a clathrochelate topology. The coordination geometry of the FeIV centre is inter-mediate between a trigonal prism and a trigonal anti-prism. In the crystal, the complex anions are connected through two Li cations into dimers, which are connected by Li-O bonds, forming infinite chains along the b-axis direction.

Crystal structure of bis-(3-carb-oxy-1-methyl-pyrid-inium) octa-bromide.

The crystal structure of the title salt, bis-(3-carb-oxy-1-methyl-pyridinium) octa-bromide, 2C7H8NO2 +·Br8 2-, consists of 3-carb-oxy-1-methyl-pyridinium (N-methyl-nicotinic acid) cations, which are stacked between relatively rare [Br8]2- anions. The polybromide [Br8]2- anion has point group symmetry and can be described as being composed of two [Br3]- anions connected with a Br2 mol-ecule in a Z-shaped manner. Contacts between neighboring octa-bromide anions ensure the creation of pseudo-polymeric chains propagating along [111]. The organic cations are located between anionic chains and are connected to each other through O-H⋯O hydrogen bonds and to the [Br8]2- anions through π⋯Br inter-actions that induce the creation of a supra-molecular tri-periodic network. In addition, the presence of weak C-H⋯Br contacts leads to the creation of layers, which align parallel to (11).

Collapsed Cu(II)-hydroxamate metallacrowns.

Degradation of a strained, thermodynamically destabilized pentanuclear copper(II) 12-metallacrown-4 complex based on a picoline hydroxamic acid resulted in the formation of the tetranuclear compounds which are the first examples of solely hydroxamate-based Cu(II) metallacrown complexes with a collapse of the metallamacrocyclic cavity.

Tris(2,2'-bipyridine-κ(2)N,N')cobalt(III) bis-[bis-(pyridine-2,6-dicarboxyl-ato-κ(3)O(2),N,O(6))cobaltate(III)] perchlorate dimethyl-formamide hemisolvate 1.3-hydrate.

In the title compound, [Co(C(10)H(8)N(2))(3)][Co(C(7)H(3)NO(4))(2)](2)(ClO(4))·0.5C(3)H(7)NO·1.3H(2)O, the Co(III) atom in the complex cation is pseudoocta-hedrally coordinated by six N atoms of three chelating bipyridine ligands. The Co(III) atom in the complex anion is coordinated by two pyridine N atoms and four carboxyl-ate O atoms of two doubly deprotonated pyridine-2,6-dicarboxyl-ate ligands in a distorted octa-hedral geometry. One dimethyl-formamide solvent mol-ecule and two water mol-ecules are half-occupied and one water mol-ecule is 0.3-occupied. O-H⋯O hydrogen bonds link the water mol-ecules, the perchlorate anions and the complex anions. π-π inter-actions between the pyridine rings of the complex anions are also observed [centroid-centroid distance = 3.804 (3) Å].

Poly[µ-aqua-diaquabis-[µ-2-cyano-2-(oxidoimino)-acetato]-copper(II)dipotassium].

In the title compound, [CuK(2)(C(3)N(2)O(3))(2)(H(2)O)(3)](n), the Cu(2+) atom is in a distorted square-pyramidal coordination geometry. Two N atoms belonging to the oxime groups and two O atoms belonging to the carboxyl-ate groups of two trans-disposed doubly deprotonated residues of 2-cyano-2-(hy-droxy-imino)-acetic acid make up the basal plane and the apical position is occupied by the water mol-ecule. The neighboring Cu-containing moieties are linked into a three-dimensional framework by K-O and K-N contacts formed by two potassium cations with the carboxyl-ate and the oxime O atoms and the nitrile N atoms of the ligand. The environments of the K(+) cations are complemented to octa- and nona-coordinated, by K-O contacts with H(2)O mol-ecules. The crystal structure features O-H⋯O hydrogen bonds.

catena-Poly[[tetra-kis-(3,5-dimethyl-1H-pyrazole-κN 2)copper(II)]-µ2-sulfato-κ2 O:O']: crystal structure and Hirshfeld surface analysis of a CuII coordination polymer.

The title coordination polymer, [Cu(SO4)(C5H8N2)4] n , was synthesized using a one-pot reaction of copper powder, anhydrous copper(II) sulfate and 3,5-dimethyl-1H-pyrazole (Hdmpz) in aceto-nitrile under ambient conditions. The asymmetric unit can be described as a chain consisting of four [Cu(SO4)(Hdmpz)4] formula units that are connected to each other by a µ2-sulfato-bridged ligand. The octa-hedral coordination geometry (O2N4) of all copper atoms is realized by coordination of four pyrazole ligands and two sulfate ligands. Four pyridine-like N atoms of the pyrazole ligands occupy the equatorial positions, while two oxygen atoms of two sulfate ligands are in axial positions. As a result of the sulfate ligand rotation, there is a pairwise alternation of terminal O atoms (which are not involved in coordination to the copper atom) of the SO4 tetra-hedra. The Cu⋯Cu distances within one asymmetric unit are in the range 7.0842 (12)-7.1554 (12) Å. The crystal structure is built up from polymeric chains packed in a parallel manner along the b-axis direction. Hirshfeld surface analysis suggests that the most important contributions to the surface contacts are from H⋯H (74.7%), H⋯O/O⋯H (14.8%) and H⋯C/C⋯H (8.2%) inter-actions.

Crystal structure of poly[[di-aqua-tetra-µ2-cyanido-platinum(II)iron(II)] methanol 4/3-solvate]: a three-dimensional Hofmann clathrate analogue.

In the title polymeric coordination compound, {[FePt(CN)4(H2O)2]·1.33CH3OH} n , the FeII cation (site symmetry 4/mm.m) is coordinated by the N atoms of four cyanide anions (CN-) and the O atoms of two water mol-ecules, forming a nearly regular [FeN4O2] octa-hedron. According the Fe-N and Fe-O bond lengths, the FeII atom is in the high-spin state. The cyanide anions act in a bridging manner to connect the FeII and PtII atoms. The [Pt(CN)4]2- moieties (Pt with site symmetry 4/mm.m) have a perfect square-planar shape. The latter anion is located perpendicular to the FeN4 plane, thus ensuring the creation of a three-dimensional framework. The crystal structure features methanol solvent mol-ecules of which 4/3 were located per FeII cation. These solvent mol-ecules are located in hexa-gonal pores; they inter-act with coordinating water mol-ecules through weak hydrogen bonds. Other guest mol-ecules could not be modelled in a satisfactory way and their contribution to the scattering was removed by a mask procedure.

Diaqua-bis-(pyridine-2-carboxyl-ato-κN,O)manganese(II) dimethyl-formamide hemisolvate.

There are two crystallographically independent complex mol-ecules with very similar geometries in the unit cell of the title compound, [Mn(C(6)H(4)NO(2))(2)(H(2)O)(2)]·0.5C(3)H(7)NO. The central ion is situated in a distorted octa-hedral environment of two N- and four O-donor atoms from two pyridine-2-carboxyl-ate ligands and two cis-disposed water mol-ecules. The carboxyl-ate ligands are coordinated in a chelate fashion with the formation of two five-membered rings. In the crystal, the complex mol-ecules are connected by O-H⋯O hydrogen bonds between the coordinated water mol-ecules and the uncoordinated carboxyl-ate O atoms, thus forming hydrogen-bonded walls disposed perpendicularly to the bc plane.

Poly[di-µ(2)-aqua-µ(5)-(pyridine-2,6-dicarboxyl-ato)-µ(3)-(pyridine-2,6-dicarboxyl-ato)-cobalt(II)disodium].

In the title compound, [CoNa(2)(C(7)H(3)NO(4))(2)(H(2)O)(2)](n), the Co(II) atom is coordinated by two pyridine N atoms and four carboxyl-ate O atoms from two doubly deprotonated pyridine-2,6-dicarboxyl-ate ligands in a distorted octa-hedral geometry. One Na(+) cation is coordinated by three carboxyl-ate O atoms and two water mol-ecules and the other is coordinated by five carboxyl-ate O atoms and two water mol-ecules in an irregular geometry. The bis-(pyridine-2,6-dicarboxyl-ato)cobalt complex units are connected by Na(+) cations and bridging water mol-ecules into a three-dimensional coordination network. O-H⋯O hydrogen bonds are formed between the water mol-ecules and the carboxyl-ate O atoms.

cyclo-Tetra-kis(µ-3-acetyl-4-methyl-1H-pyrazole-5-carboxyl-ato-κN,O:N,O)tetra-kis[aqua-copper(II)] tetra-deca-hydrate.

The title compound, [Cu(4)(C(7)H(6)N(2)O(3))(4)(H(2)O)(4)]·14H(2)O, a tetra-nuclear [2 × 2] grid-type complex with S4 symmetry, contains four Cu(II) atoms which are bridged by four pyrazole-carboxyl-ate ligand anions and are additionally bonded to a water molecule. Each Cu(II) atom is coordinated by two O atoms of the carboxyl-ate and acetyl groups, two pyrazole N atoms of doubly deprotonated 3-acetyl-4-methyl-1H-pyrazole-5-carb-oxy-lic acid and one O atom of a water mol-ecule. The geometry at each Cu(II) atom is distorted square-pyramidal, with the two N and two O atoms in the equatorial plane and O atoms in the axial positions. O-H⋯O hydrogen-bonding interactions additionally stabilize the structure. One of the uncoordinated water molecules shows half-occupancy.

A second solvatomorph of poly[[µ4-N,N'-(1,3,5-oxadiazinane-3,5-di-yl)bis-(carbamoyl-methano-ato)]nickel(II)dipotassium]: crystal structure, Hirshfeld surface analysis and semi-empirical geometry optimization.

The title compound, poly[tri-aqua-bis-[µ4-N,N'-(1,3,5-oxadiazinane-3,5-di-yl)bis(carbamoyl-methano-ato)]dinickel(II)tetra-potassium], [K4Ni2(C7H6N4O7)2(H2O)3] n , is a second solvatomorph of poly[(µ4-N,N'-(1,3,5-oxadiazinane-3,5-di-yl)bis-(carbamoyl-methano-ato)nickel(II)dipotassium] reported previously [Plutenko et al. (2021 ▸). Acta Cryst. E77, 298-304]. The asymmetric unit of the title compound includes two structurally independent complex anions [Ni(C7H6N4O7)]2-, which exhibit an L-shaped geometry and consist of two almost flat fragments perpendicular to one another: the 1,3,5-oxadiazinane fragment and the fragment including other atoms of the anion. The central Ni atom is in a square-planar N2O2 coordination arrangement formed by two amide N and two carboxyl-ate O atoms. In the crystal, the title compound forms a layered structure in which layers of negatively charged complex anions and positively charged potassium cations are stacked along the a-axis direction. The polymeric framework is stabilized by a system of hydrogen-bonding inter-actions in which the water mol-ecules act as donors and the carb-oxy-lic, amide and water O atoms act as acceptors.

Crystal structure and Hirshfeld surface analysis of di-µ-chlorido-bis-[(aceto-nitrile-κN)chlorido-(ethyl 5-methyl-1H-pyrazole-3-carboxyl-ate-κ2 N 2,O)copper(II)].

The title compound, [Cu2Cl4(C5H10N2O2)2(CH3CN)2] or [Cu2(µ2-Cl)2(CH3-Pz-COOCH2CH3)2Cl2(CH3CN)2], was synthesized using a one-pot reaction of copper powder, copper(II) chloride dihydrate and ethyl 5-methyl-1H-pyrazole-3-carboxyl-ate (CH3-Pz-COOCH2CH3) in aceto-nitrile under ambient conditions. This complex consists of discrete binuclear mol-ecules with a {Cu2(µ2-Cl)2} core, in which the Cu⋯Cu distance is 3.8002 (7) Å. The pyrazole-based ligands are bidentate coordinated, leading to the formation of two five-membered chelate rings. The coordination geometry of both copper atoms (ON2Cl3) can be described as distorted octa-hedral on account of the aceto-nitrile coordination. A Hirshfeld surface analysis suggests that the most important contributions to the surface contacts are from H⋯H (40%), H⋯Cl/Cl⋯H (24.3%), H⋯O/O⋯H (11.8%), H⋯C/C⋯H (9.2%) and H⋯N/N⋯H (8.3%) inter-actions.

µ-Oxalato-bis-[(2,2'-bipyridyl)-copper(II)] bis(perchlorate) dimethyl-formamide disolvate monohydrate.

The title compound, [Cu(2)(C(2)O(4))(C(10)H(8)N(2))(4)](ClO(4))(2)·2C(3)H(7)NO·H(2)O, contains doubly charged centrosymmetric dinuclear oxalato-bridged copper(II) complex cations, perchlorate anions, and DMF and water solvate mol-ecules. In the complex cation, the oxalate ligand is coordinated in a bis-bidentate bridging mode to the Cu atoms. Each Cu atom has a distorted tetra-gonal-bipyramidal environment, being coordinated by two N atoms of the two chelating bipy ligands and two O atoms of the doubly deprotonated oxalate anion. Pairs of perchlorate anions and water mol-ecules are linked into recta-ngles by O-H⋯O bonds in which the perchlorate O atoms act as acceptors and the water mol-ecules as donors. Methyl groups of the DMF solvent molecule are disordered over two sites with occupancies of 0.453 (7):0.547 (7), and the water molecule is half-occupied.