Hydrogen versus fluorine: effects on molecular structure and intermolecular interactions in a platinum isocyanate complex.

At the molecular level, the enantiomerically pure square-planar organoplatinum complex (SP-4-4)-(R)-[2-(1-aminoethyl)-5-fluorophenyl-κ(2)C(1),N][(R)-1-(4-fluorophenyl)ethylamine-κN](isocyanato-κN)platinum(II), [Pt(C8H9FN)(NCO)(C8H10FN)], and its congener without fluorine substituents on the aryl rings adopt the same structure within error. The similarities between the compounds extend to the most relevant intermolecular interactions, i.e. N-H...O and N-H...N hydrogen bonds link neighbouring molecules into chains along the shortest lattice parameter in each structure. Differences between the crystal structures of the fluoro-substituted and parent complex become obvious with respect to secondary interactions perpendicular to the classical hydrogen bonds; the fluorinated compound features short C-H...F contacts with an F...H distance of ca 2.6 Å. The fluorine substitution is also reflected in reduced backbonding from the metal cation to the isocyanate ligand.

Halogen bonds on demand: I···S contacts in cocrystals of trans-bis(thiocyanato-κN)tetrakis(4-vinylpyridine-κN)nickel(II) and 2,3,5,6-tetrafluoro-1,4-diiodobenzene.

Hydrogen bonds are considered a powerful organizing force in designing supramolecular architectures because they are directional, selective and reversible at room temperature. trans-Dithiocyanatotetrakis(4-vinylpyridine)nickel(II) is a popular host for the inclusion of small molecules and 2,3,5,6-tetrafluoro-1,4-diiodobenzene (TFDIB) represents a strong halogen-bond donor. These constituents cocrystallize in a 1:1 stoichiometry, [Ni(NCS)2(C7H7N)4]·C6F4I2, in the tetragonal space group I41/a. Both residues occupy special positions, i.e. the pseudo-octahedral Ni(II) complex is located on a twofold axis and the TFDIB molecule sits about a crystallographic centre of inversion. The components interact via a short S···I contact of 3.2891 (12) Šbetween the thiocyanate S atom of the host and the iodine substituent at the perhalogenated aromatic ring of the smaller guest molecule. This interaction meets the commonly accepted criteria for a halogen bond. Such halogen bonds to sulfur are significantly less common than to smaller electronegative atoms.

N-(6-Methylpyridin-2-yl)mesitylenesulfonamide and acetic acid--a salt, a cocrystal or both?

In the solid obtained from N-(6-methylpyridin-2-yl)mesitylenesulfonamide and acetic acid, the constituents interact via two N-H···O hydrogen bonds. The H atom situated in one of these short contacts is disordered over two positions: one of these positions is formally associated with an adduct of the neutral sulfonamide molecule and the neutral acetic acid molecule, and corresponds to a cocrystal, while the alternative site is associated with salt formation between a protonated sulfonamide molecule and deprotonated acetic acid molecule. Site-occupancy refinements and electron densities from difference Fourier maps suggest a trend with temperature, albeit of limited significance; the cocrystal is more relevant at 100 K, whereas the intensity data collected at room temperature match the description as cocrystal and salt equally well.

Bis[4-amino-N-(pyrimidin-2-yl)benzenesulfonamido]diamminecopper(II): aqua or ammine ligands?

Diffraction results obtained at 100 and 291 K, the former at high resolution, are reported for the title compound, [Cu(C10H9N4O2S)2(NH3)2] or [Cu(sulfa)2(NH3)2] [Hsulfa is 4-amino-N-(pyrimidin-2-yl)benzenesulfonamide]. The Cu(II) cation is coordinated by two N-atom donors from a bidentate sulfa ligand, by two ammonia molecules in the equatorial plane and by a monohapto (η(1)) sulfadiazine at the apex of a distorted square pyramid. The present interpretation and two earlier reports [Brown, Cook & Sengier (1987). Acta Cryst. C43, 2332-2334; Tommasino, Renaud, Luneau & Pilet (2011). Polyhedron, 30, 1663-1670] disagree about the nature and geometry of the ligands. The relationship between the present result and the former is discussed, and evidence is provided that the latter erroneously assigned an ammine as an aqua ligand.

Pseudosymmetry in a cyclopalladated compound.

The enantiomerically pure title complex, [SP-4-4]-(R)-[2-(1-aminoethyl)phenyl-κ(2)C(1),N]chlorido(quinoline-κN)palladium(II) acetone hemisolvate, [Pd(C(8)H(10)N)Cl(C(9)H(7)N)]·0.5C(3)H(6)O, crystallizes with four molecules of the organopalladium complex and two molecules of acetone in the asymmetric unit. This corresponds to a discrete hydrogen-bonded aggregate and to the content of the unit cell in the space group P1. Pronounced pseudo-inversion symmetry relates pairs of these objects in the asymmetric unit.

The molecular conformation of pentan-3-one studied in cholic acid pentan-3-one solvate.

The crystal structure of cholic acid-pentan-3-one (1/1), C(5)H(10)O·C(24)H(40)O(5), has been determined in order to deduce the molecular conformation of the small volatile ketone. Data were collected at 100 K to a resolution of (sin θ)/λ = 0.91 Å(-1). The structure contains a hydrogen-bonded cholic acid host network, forming only van der Waals interactions with the guest pentan-3-one molecules. The ketone molecules are disordered on general positions, with two clearly identifiable conformations. The majority conformer exhibits approximate C(2) symmetry and is similar to that recently observed by microwave spectroscopy in the gas phase.

One of the most complex "small molecule structures" ever reported: 16 independent molecules in the asymmetric unit for an ortho-palladated primary amine.

The presumably "small molecule structure" of the organopalladium complex rac-PdCl(C(6)H(3)-4-OMe-CHMeNH(2))(py) crystallizes with 16 molecules in the asymmetric unit, a highly unusual situation according to the CSD database. The symmetrically independent residues differ with respect to soft conformational degrees of freedom. Packing in the acetonitrile solvate of the same compound is unexceptional.

[rac-2-(1-Amino-eth-yl)phenyl-κC,N](ethyl-endiamine-κN,N')palladium(II) 3-methyl-benzoate monohydrate.

In the title compound, [Pd(C(8)H(10)N)(C(2)H(8)N(2))](C(8)H(7)O(2))·H(2)O, the palladium ion is coordinated in a distorted square-planar fashion by the two N atoms from the chelating ethyl-enediamine group and by the N and a C atom of the deprotonated chiral amine. The resulting cationic complex, the 3-methyl-benzoate anion and the hydrate water mol-ecule are inter-connected by N-H⋯O and O-H⋯O hydrogen bonds.

[rac-2-(1-Amino-eth-yl)phenyl-κC,N](ethyl-endiamine-κN,N')palladium(II) 3,5-dimethyl-benzoate.

In the title compound, [Pd(C(8)H(10)N)(C(2)H(8)N(2))](C(9)H(9)O(2)), the palladium ion is coordinated in a distorted square-planar fashion by the two N atoms from the chelating ethyl-enediamine group and by the N and a C atom of the deprotonated chiral amine. The resulting cationic complex and the 3,5-dimethyl-benzoate anion are inter-connected by N-H⋯O hydrogen bonds.

Robust packing in cyclopalladated primary amines: isomorphous crystal structures of four complexes with varying substitution patterns.

The crystal structures of (SP-4-4)-[rac-2-(1-aminoethyl)phenyl-kappa(2)C(1),N]chlorido(pyridine-kappaN)palladium(II), [Pd(C(8)H(10)N)Cl(C(5)H(5)N)], (I), (SP-4-4)-[rac-2-(1-aminoethyl)phenyl-kappa(2)C(1),N]bromido(pyridine-kappaN)palladium(II), [PdBr(C(8)H(10)N)(C(5)H(5)N)], (II), (SP-4-4)-[rac-2-(1-aminoethyl)-5-bromophenyl-kappa(2)C(1),N]bromido(4-methylpyridine-kappaN)palladium(II), [PdBr(C(8)H(9)BrN)(C(6)H(7)N)], (III), and (SP-4-4)-[rac-2-(1-aminoethyl)-5-bromophenyl-kappa(2)C(1),N]iodido(4-methylpyridine-kappaN)palladium(II), [Pd(C(8)H(9)BrN)I(C(6)H(7)N)], (IV), are reported. The latter is the first iodide complex in this class of compounds. All four complexes crystallize in the same space group, viz. I4(1)/a, with very similar lattice parameters a and more flexible lattice parameters c. Their packing corresponds to that of their enantiomerically pure congeners, which crystallize in the t2 subgroup I4(1).