Curved crystal morphology, photoreactivity and photosalient behaviour of mononuclear Zn(II) complexes.

A dramatic effect of crystal morphology, photoreactivity and photosalient property is observed in a zinc(II) complex due to solvent effects and fluorine substitution at the backbone of the ligand. Of the two crystal forms with a 3-fluoro derivative, one yielded a curved morphology of single crystals and the second form shows photoreactivity in the solid state, whereas crystals of the 2-fluoro derivative pop during the [2 + 2] photocycloaddition reaction. This is the first report documenting curved single crystals of metal complexes obtained naturally during crystallization, although such bent crystals have been observed in extended solids naturally, or bent by mechanical force or by UV irradiation.

Molecular Scissoring: Facile 3D to 2D Conversion of Lanthanide Metal Organic Frameworks Via Solvent Exfoliation.

Five lanthanide MOFs with pcu topology have been exfoliated into nanoplatelets of two-dimensional structures via sonication in the dimethylacetamide solvent. These nanosheets are fluorescent under two-photon excitation dominated by the ligand, indicating energy upconversion ability.

Thermal cleavage of cyclobutane rings in photodimerized coordination-polymeric sheets.

Three coordination polymers, [Cd(2)(pvba)(2)(tbdc)(dmf)(2)] (1), [Co(2)(pvba)(2)(tbdc)(dmf)(2)(H(2)O)(2)] (2), and [Ni(2)(pvba)(2)(tbdc)(dmf)(2)(H(2)O)(2)] (3) (H(2)tbdc = 2,3,5,6-tetrabromobenzenedicarboxylic acid, Hpvba = trans-2-(4'-pyridyl)vinylbenzoic acid), were synthesized by solvothermal methods. The solid-state structures of compounds 1 and 2 were determined by X-ray crystallography. In compounds 1 and 2, the bimetallic cores acted as secondary building units that connected the tbdc ligands in one direction and a pair of pvba ligands, which were aligned in a head-to-tail parallel manner, in the orthogonal direction to form sheet structures. The C=C bonds in these pvba ligand pairs in all three compounds were well-aligned to undergo quantitative [2+2] cycloaddition reactions in the solid state under UV irradiation, thereby yielding their cyclobutane derivatives. This photochemical reaction appeared to facilitate structural transformations from one 2D structure into another in the solid state. The photoreactive Co(II)- and Ni(II) coordination polymers exhibited a reversible dehydration-rehydration reaction that was accompanied by color changes from pink to purple and green to yellow, respectively, owing to a change in coordination number from six to five. Magnetic studies showed that compound 2 was an antiferromagnet, which displayed a field-dependent transition with a critical field (H(c)) of 40 kOe at 2 K; the antiferromagnetic interaction between the Co(2) units was strengthened and weakened by dehydration and UV irradiation, respectively. The cyclobutane ligand in the photodimerized products was cleaved on heating to yield a mixture of trans- and cis-isomers of pvba, as monitored by (1)H NMR spectroscopy. The Cd(II) coordination polymer underwent quantitative cleavage of the cyclobutane ring whilst the other two underwent partial cleavage.

Photoreactive gold(I) macrocycles with diphosphine and trans,trans-muconate ligands.

A pair of trans,trans-muconate ligands have been successfully aligned in two novel Au(I) macrocycles by design from phosphino metal precursors that undergo photochemical cycloaddition reactions quantitatively, resulting in the formation of cyclooctadiene derivatives.

Role of anions in the synthesis of cyclobutane derivatives via [2 + 2] cycloaddition reaction in the solid state and their isomerization in solution.

trans-3-(4'-Pyridyl)acrylic acid (4-PA) is inert to photodimerization reaction both in solution and solid state. It is made photoreactive by forming salts with various acids. The anions of these salts play a key role in directing the packing of 4-PAH(+) in the solid state. The anions CF(3)CO(2)(-), Cl(-), ClO(4)(-), and BF(4)(-) direct the parallel alignments of 4-PAH(+) in head-to-tail (HT) fashion and lead to the formation of HT-photodimer. On the other hand, bivalent anion SO(4)(2-) directs parallel alignment of 4-PAH(+) in head-to-head (HH) fashion and lead to the formation of HH-photodimer. The details of the anion-controlled stereoselective syntheses of these two cyclobutane derivatives are presented. Interestingly, both cyclobutane compounds undergo isomerization from rctt-form to rctc-form in solution catalyzed by acid.

7-(4-Fluoro-benzyl-amino)-2-phenyl-1,2,4-triazolo[1,5-a][1,3,5]triazin-5-amine methanol disolvate.

The 1,2,4-triazolo[1,5-a][1,3,5]triazine system in the title compound, C(17)H(14)FN(7)·2CH(3)OH, is essentially planar, with an r.m.s. deviation of 0.0215 Å. The attached phenyl ring lies almost in the mean plane of the heterocyclic core [dihedral angle = 3.56 (4)°]. In the crystal, centrosymmetric inversion dimers connected via inter-molecular N-H⋯N hydrogen bonds between H atom of the primary amino group and the triazine N atom [R(2) (2)(8) graph-set motif] form sheets parallel to (010). A second set of dimers connected via N-H⋯F hydrogen bonds between the other H atom of the primary amino group and the F atom forms an R(2) (2)(24) graph-set motif linking the sheets. Methanol solvent mol-ecules are packed in channels running along the [010] direction.

A novel heteroleptic paddlewheel diruthenium bicyclic guanidinate complex: synthesis, structure, and scope.

A novel paddlewheel or 'lantern' heteroleptic diruthenium guanidinate complex Ru(2)(TBO)(2)(OAc)(2)Cl x 3MeCN (1 x 3MeCN) was synthesized and structurally characterized. Compared with a known tetra-substituted di-ruthenium guanidinate complex Ru(2)(TBD)(4)Cl, 1 revealed structural dissimilarities with internal twisting.

N'-Acetyl-5-amino-1-methyl-1H-pyrazole-4-carbohydrazonamide dihydrate.

In the title compound, C(7)H(12)N(6)O·2H(2)O, the Z configuration of the hydrazone fragment is stabilized by an intra-molecular N-H⋯N hydrogen bond involving one of the amino groups. In the crystal structure, the hydrazonamide mol-ecules are connected via inter-molecular N-H⋯O=C hydrogen bonds, forming C(7) chains running along [010]. The chains form sheets parallel to the (01). The chains are cross-linked by water mol-ecules to form a three-dimensional hydrogen-bonded network.

4-Carbethoxy-1-[4-(N,N-dimethylamino)benzoyl]thiosemicarbazide.

The mol-ecular structure of the title compound, C(13)H(18)N(4)O(3)S, (systematic name: ethyl N-{2-[4-(dimethyl-amino)benzo-yl]hydrazinethio-carbon-yl}carbamate) is stabilized by intra-molecular N-H⋯O=C hydrogen bonding arranged in an S(6) graph-set motif. In the crystal, inversion dimers connected via inter-molecular N-H⋯S=C hydrogen bonds [R(2) (2)(8) graph-set motif] form sheets parallel to the (21) plane. Dimers are also formed by the mol-ecules via weak inter-molecular N-H⋯S=C hydrogen bonds [R(2) (2)(10) graph-set motif] connecting the sheets.

N-Carbethoxy-N'-(3-phenyl-1H-1,2,4-triazol-5-yl)thiourea.

The title compound {systematic name: ethyl N-[N-(3-phenyl-1H-1,2,4-triazol-5-yl)carbamothio-yl]carbamate}, C(12)H(13)N(5)O(2)S, exists in the 3-phenyl-5-thio-ureido-1H-1,2,4-triazole tautomeric form stabilized by intra-molecular hydrogen bonding between the endocyclic NH H atom and the thio-ureido S atom. The mol-ecular structure is also stabilized by intra-molecular N-H⋯O=C hydrogen bonds arranged in an S(6) graph-set motif within the carbethoxy-thio-urea moiety. The mean planes of the phenyl and 1,2,4-triazole rings make a dihedral angle of 7.61 (11)°. In the crystal, the mol-ecules form two types of inversion dimers. Inter-molecular hydrogen bonds are arranged in R(2) (2)(6) and R(2) (2)(8) graph-set motifs, together forming a network parallel to (111).

N-Carbethoxy-N'-[3-(4-methylphenyl)-1H-1,2,4-triazol-5-yl]thiourea.

THE TITLE COMPOUND, [SYSTEMATIC NAME: ethyl ({[3-(4-methylphenyl)-1H-1,2,4-triazol-5-yl]amino}carbonothioyl)carbamate], C(13)H(16)N(5)O(2)S, exists in the 3-aryl-5-thio-ureido-1H-1,2,4-triazole tautomeric form. The mol-ecular structure is stabilized by intra-molecular hydrogen bonding (N-H⋯S=C between the endocyclic N-bound H atom and the thio-ureido S atom, and N-H⋯O=C within the ethoxy-carbonyl-thio-urea unit), both arranged in an S(6) graph-set motif. The mean planes of the phenyl and 1,2,4-triazole rings make a dihedral angle of 6.59 (10)°. In the crystal structure, the mol-ecules form two types of centrosymmetric dimers connected by inter-molecular hydrogen bonds; in the first, the N-NH triazole sides of two mol-ecules are connected [R(2) (2)(6) graph-set motif] and the second is an N-H⋯S=C inter-action between the imide H atoms and the thio-carbonyl S atoms [R(2) (2)(8) graph-set motif]. Together, they form a network parallel to the (111) plane.

8-Methyl-2-[4-(trifluoro-meth-yl)phen-yl]-8H-pyrazolo-[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine methanol disolvate.

In the title compound, C(14)H(10)F(3)N(7)·2CH(4)O, the heterocyclic ring system is essentially planar (r.m.s. deviation = 0.009 Å) and makes a dihedral angle of 6.91 (8)° with the attached benzene ring. In the crystal, the main mol-ecules form centrosymmetric R(2) (2)(8) dimers via pairs of N-H⋯N hydrogen bonds between the amino groups and pyrimidine N atoms. One of the independent methanol mol-ecules and its inversion equivalent are linked to the dimers via O-H⋯N and N-H⋯O hydrogen bonds, forming R(4) (4)(16) graph-set motifs. The dimers along with the hydrogen-bonded methanol mol-ecules are stacked along the a axis, with π-π inter-actions between the pyrazole and triazole rings [centroid-centroid distance = 3.4953 (10) Å].

A monoclinic polymorph of N-eth-oxy-carbonyl-N'-(3-phenyl-1H-1,2,4-triazol-5-yl)thio-urea.

The title compound, C(12)H(13)N(5)O(2)S {systematic name: ethyl N-[N-(3-phenyl-1H-1,2,4-triazol-5-yl)carbamothio-yl]carbamate}, is a monoclinic polymorph (space group P2(1)/c) which crystallizes with three similar independent mol-ecules in the asymmetric unit. The triazole ring makes dihedral angles of 6.6 (2), 8.4 (2) and 10.6 (2)° with the phenyl ring in the three independent molecules. The structure was previously reported [Dolzhenko et al. (2010a ▶). Acta Cryst., E46, o425] as a triclinic polymorph crystallizing in space group P. Mol-ecules in both polymorphs possess two S(6) rings generated by intra-molecular N-H⋯S and N-H⋯O hydrogen bonds, resulting in similar mol-ecular geometries. However, the two polymorphs differ in the crystal packing. In contrast to the dimers of the triclinic polymorph, mol-ecules of the monoclinic polymorph are connected by inter-molecular N-H⋯S and N-H⋯N hydrogen bonds, forming pseudosymmetric trimers arranged in sheets parallel to (302).

4-Amino-2,8-dimethyl-6H-pyrimido[1,2-a][1,3,5]triazin-6-one.

In the title compound, C(8)H(9)N(5)O, the mean planes through the pyrimidine and triazine rings form a dihedral angle of 2.83 (16)°. The amino group adopts a trigonal-planar configuration and forms an intra-molecular resonance-assisted N-H⋯O=C hydrogen bond with the carbonyl group. In the crystal, mol-ecules are linked via inter-molecular N-H⋯N hydrogen bonds into chains of C(2) (2)(6)[R(2) (2)(6)] motif. The molecules form two types of sheet parallel to (201) and (01), respectively.

4,4-Dimethyl-3,4-dihydro-pyrido[2',3':3,4]pyrazolo-[1,5-a][1,3,5]triazin-2-amine ethanol monosolvate.

In the title compound, C(10)H(12)N(6)·C(2)H(5)OH, the planarity of the heterocyclic system is slightly distorted at the triazine ring (r.m.s. deviation = 0.1191 Å), which adopts a conformation best described as inter-mediate between a flattened twisted boat and a half-boat with the tertiary Csp(3) atom at the bow. In the crystal, mol-ecules form centrosymmetric dimers connected by N⋯H-O and O⋯H-N hydrogen bonds between the amino group H atom, the ethanol solvent mol-ecule and the triazine N atom, making an R(4) (4)(12) graph-set motif. The other H atom of the amino group and the H atom on the endocyclic N atom form N⋯H-N hydrogen bonds with the N atoms of the pyrazole and pyridine rings, respectively, linking the mol-ecules into C(7)C(7) chains with the R(2) (2)(8) binary graph-set motif running along [010].

2-Phenyl-7-(4-pyridyl-methyl-amino)-1,2,4-triazolo[1,5-a][1,3,5]triazin-5(4H)-one.

In the title compound, C(16)H(13)N(7)O, the 1,2,4-triazolo[1,5-a][1,3,5]triazine heterocyclic system is essentially planar (r.m.s. deviation = 0.0375 Å). The attached benzene ring lies almost in the mean plane of 1,2,4-triazolo[1,5-a][1,3,5]triazine [dihedral angle = 1.36 (23)°], while the pyridine ring is turned out of this plane by the amino-methyl bridge [dihedral angle = 69.22 (9)°]. The amino group H atom is involved in intra-molecular hydrogen bonding with a triazole N atom. In the crystal, mol-ecules are connected via C(=O)NH⋯N hydrogen bonds into C(11) chains parallel to [100]. The amino group H atom acts as a hydrogen-bond donor, forming an NH⋯O=C hydrogen bond with the carbonyl O atom, which links the mol-ecules into C(6) chains running along [011] and [01].

Anion-controlled stereoselective synthesis of cyclobutane derivatives by solid-state [2 + 2] cycloaddition reaction of the salts of trans-3-(4-pyridyl) acrylic acid.

Two stereoisomers of cyclobutane derivatives with pyridyl and carboxylic acid functionalities have been stereoselectively synthesized by a solid-state photochemical [2 + 2] cycloaddition reaction in quantitative yields. The head-to-head and head-to-tail parallel orientations of the monomers, required to obtain these two isomers, have been controlled by the anions present in the salts. The photoinert behavior of these salts in solution signifies the importance of the solid-state synthesis of these cyclobutane derivatives.

2-Amino-4-(4-bromo-phen-yl)-8-trifluoro-methyl-3,4-dihydropyrimido[1,2-a][1,3,5]triazin-6(5H)-one.

The title compound, C(13)H(9)BrF(3)N(5)O, crystallizes with two independent mol-ecules in the asymmetric unit. The pyrimidine rings of the mol-ecules are planar [maximum deviations 0.053 (3) and 0.012 (3) Å], while the triazine rings adopt flattened half-boat conformations with the p-bromo-phenyl rings in the flagpole positions. The crystal packing is stabilized by a three-dimensional network of inter-molecular N-H⋯N, N-H⋯O and N-H⋯F hydrogen bonds.

(4Z,6Z,12Z,14Z)-2,10-Dimethyl-2,8,10,16-tetra-hydro-dipyrazolo[3,4-e:3',4'-l][1,2,4,8,9,11]hexa-azacyclo-tetra-decine-4,12-diamine.

The title compound, C(12)H(16)N(12), is a centrosymmetric mol-ecule which comprises of a hexa-aza[14]annulene macrocyclic ring fused with two pyrazole rings. The macrocyclic ring is essentially planar, with an r.m.s. deviation of 0.0381 Å. The electron pairs of the amino groups are delocalized with the conjugated system of the macrocycle. Strong intra-molecular N-H⋯N hydrogen bonds arranged in an S(2) (2)(10) graph-set motif are present in the macrocyclic ring. In the crystal, the amino groups act as donors for inter-molecular N-H⋯N inter-actions with the N atoms of the heterocyclic system, forming a network of two types of extended chains oriented parallel to the [101] and [011] directions. The crystal packing is also stabilized by weak inter-molecular C-H⋯N hydrogen bonds formed between pyrazole C-H groups and N atoms of the macrocyclic ring, running in the [10] direction.