Search

A steric parameter (θN-sub) is introduced to describe the steric bulk at the nitrogen atom on a range of PNP ligands used in ethylene tri- and tetramerization. This parameter was calculated for the free ligands and different metal complexes thereof and compared to catalytic data. A specific tendency is observed for the value of θN-sub and 1-hexene selectivity, and a slight increase in 1-octene selectivity is found with increased bulkiness of the substituents on the nitrogen atom.

Water-soluble fac-[Re(CO)(3)(L,L'-Bid)(X)] (L,L'-Bid = tropolonato, X = H(2)O, methanol) complexes have been synthesized, and the aqua and methanol substitution reactions were investigated in water (pH range 6.3-10.0) and methanol, respectively, and compared. Thiocyanate ions were used as monodentate entering ligand. The complexes were characterized by UV-vis, IR, and NMR spectroscopy. The crystal structures of the complexes [NEt(4)] fac-[Re(Trop)(CO)(3)(H(2)O)].NO(3).H(2)O (reactant) and fac-[Re(CO)(3)(Trop)(Py)], a substitution product, are reported. Overall it was found that the aqua substitution of fac-[Re(CO)(3)(Trop)(H(2)O)] is about 10 times faster than the methanol substitution reaction for fac-[Re(CO)(3)(Trop)(MeOH)], with forward and reverse rate and stability constants [k(1) (M(-1) s(-1)), k(-1) (s(-1)), K(1), (M(-1))] for thiocyanate as monodentate entering ligand as follows: fac-[Re(CO)(3)(Trop)(H(2)O)] = 2.54 ± 0.03, 0.0077 ± 0.0005, 330 ± 22/207 ± 14 and fac-[Re(CO)(3)(Trop)(MeOH)] = 0.268 ± 0.002, 0.0044 ± 0.0002, (61 ± 3)/(52 ± 4). The activation parameters [ΔH(‡)(k1) (kJ mol(-1)), ΔS(‡)(k1) (J K(-1) mol(-1))] for the aqua and methanol complex respectively are 56.1 ± 0.7, -49 ± 2 and 64 ± 1, -43 ± 5.

In the title compound, [Zr(C(11)H(10)NO)(4)]·2C(3)H(7)NO, the Zr(IV) ion is coordinated by four bidentate 5,7-dimethylquinolin-8-olate ligands in a slightly distorted square-anti-prismatic coordination environment. The asymmetric unit also contains two N,N'-dimethyl-formamide (DMF) solvent mol-ecules. In the crystal, a weak C-H⋯O hydrogen bond links the complex mol-ecule to a solvent mol-ecule and weak π-π stacking inter-actions [centroid-centroid distance = 3.671 (3) Å] also occur. One of the DMF solvent mol-ecules was refined as disordered over three sets of sites, with refined occupancies in the ratio of 0.391 (9):0.342 (10):0.267 (7).

In the title compound, [Nb(CH(3)O)(2)(C(5)H(7)O(2))Cl(2)], a slightly distorted octa-hedral coordination geometry is observed around the Nb(V) atom with Nb-O distances in the range of 1.8254 (16)-2.0892 (16) Å and Nb-Cl distances of 2.3997 (14) and 2.4023 (12) Å. The O-Nb-O angles vary between 81.36 (7) and 172.65 (7) °, while the trans Cl-Nb-Cl angle is 167.34 (2)°. There are no hydrogen bonds observed.

In the title salt, C(15)H(13)N(4)O(+)·NO(3) (-), an extensive network of N-H⋯N, N-H⋯O and C-H⋯O hydrogen-bond inter-actions are observed throughout the structure. Further stabilization is obtained by π-π stacking inter-actions between inversion-related quinoline systems and inversion-related pyridine rings, with respective centroid-centroid distances of 3.5866 (6) and 3.3980 (6) Å.

In the title compound, C(20)H(18)N(4)O(2), the dihedral angles between the central benzene ring and the pyridine rings are 57.55 (6) and 22.05 (8)°. The mol-ecular conformation is stabilized by intra-molecular N-H⋯N inter-actions and in the crystal structure an inter-molecular asymmetric cyclic hydrogen-bonding association involving both amide N-H donors and a common amide O-atom acceptor gives a chain extending along the c axis.

In the title compound, [Ir(C(18)H(15)P)(2)(CO)(3)]PF(6)·CH(3)OH, the Ir(I) atom is coordinated by two triphenyl-phosphine ligands in axial sites and three carbonyl ligands in the equatorial plane of a fairly regular trigonal bipyramid: the equatorial C-Ir-C angles range from 115.45 (9) to 126.42 (10)°. The small deviations from the ideal tetra-hedral geometry around the P atoms are illustrated by C-P-C angles ranging from 104.08 (9) to 106.46 (9)°. In the crystal, the mol-ecules are linked by weak C-H⋯F, C-H⋯O and C-H⋯π inter-actions.

The title compound, [Pt(C₂₉H₂₉NP₂)₂](CF₃SO₃)₂, consists of a Pt(II) atom, situated on an inversion centre, coordinated by two diphosphinoamine bidentate ligands and charge-balanced by two trifluoro-methane-sulfonate anions. The Pt(II) atom has a distorted square-planar geometry defined by the four P atoms. The distortion is illustrated by the P-Pt-P bite angle of 70.31 (4)°. The geometry around the N atom deviates from a trigonal-planar geometry, evidenced by the P-N-P bite angle of 102.3 (2) °. The N atom is displaced by 0.114 (4) Å from the C/P/P plane. In order to coordinate, the orientation of the phenyl rings alters from a C(s) conformation to a C(2v) conformation. The cyclo-pentane ring is slightly twisted: the puckering parameters are q(2) = 0.420 (5) Å and ϕ = 26.5 (8) °. The trifluoro-methane-sulfonate anion displays a 0.511 (11):0.489 (11) positional disorder. Weak inter- and intra-molecular C-H⋯O hydrogen bonds influence the crystal packing.

The title compound, fac-[Re(C(12)H(12)N(3))(CO)(3)]Br·0.5H(2)O, crystallizes with a cationic rhenium(I) unit, a bromide ion and half a water mol-ecule, situated on a twofold rotation axis, in the asymmetric unit. The Re(I) atom is facially surrounded by three carbonyl ligands and a tridentate bis-(pyridin-2-ylmeth-yl)amine ligand in a distorted octahedral environment. N-H⋯Br, O-H⋯Br, C-H⋯O and C-H⋯Br hydrogen bonds are present in the crystal structure and π-π stacking is also observed [centroid-centroid distances = 3.669 (1) Å and 4.054 (1) Å], giving rise to a three-dimentional network. The mol-ecules pack in a head-to-head fashion along the ac plane.

The title compound, C(14)H(12)FNO, crystallizes as the trans phenol-imine tautomer. The two benzene rings are essentially coplanar, being inclined to one another by 9.28 (7)°. This is at least in part due to the intra-molecular O-H⋯N hydrogen bond between the hy-droxy O atom and the imine N atom. The crystal structure is stabilized by an array of weak C-H⋯O and C-H⋯F inter-actions, which link the mol-ecules into a stable three-dimensional network.

A range of fac-[Re(CO)(3)(L,L'-Bid)(H(2)O)](n) (L,L'-Bid = neutral or monoanionic bidentate ligands with varied L,L' donor atoms, N,N', N,O, or O,O': 1,10-phenanthroline, 2,2'-bipydine, 2-picolinate, 2-quinolinate, 2,4-dipicolinate, 2,4-diquinolinate, tribromotropolonate, and hydroxyflavonate; n = 0, +1) has been synthesized and the aqua/methanol substitution has been investigated. The complexes were characterized by UV-vis, IR and NMR spectroscopy and X-ray crystallographic studies of the compounds fac-[Re(CO)(3)(Phen)(H(2)O)]NO(3)·0.5Phen, fac-[Re(CO)(3)(2,4-dQuinH)(H(2)O)]·H(2)O, fac-[Re(CO)(3)(2,4-dQuinH)Py]Py, and fac-[Re(CO)(3)(Flav)(CH(3)OH)]·CH(3)OH are reported. A four order-of-magnitude of activation for the methanol substitution is induced as manifested by the second order rate constants with (N,N'-Bid) < (N,O-Bid) < (O,O'-Bid). Forward and reverse rate and stability constants from slow and stopped-flow UV/vis measurements (k(1), M(-1) s(-1); k(-1), s(-1); K(1), M(-1)) for bromide anions as entering nucleophile are as follows: fac-[Re(CO)(3)(Phen)(MeOH)](+) (50 ± 3) × 10(-3), (5.9 ± 0.3) × 10(-4), 84 ± 7; fac-[Re(CO)(3)(2,4-dPicoH)(MeOH)] (15.7 ± 0.2) × 10(-3), (6.3 ± 0.8) × 10(-4), 25 ± 3; fac-[Re(CO)(3)(TropBr(3))(MeOH)] (7.06 ± 0.04) × 10(-2), (4 ± 1) × 10(-3), 18 ± 4; fac-[Re(CO)(3)(Flav)(MeOH)] 7.2 ± 0.3, 3.17 ± 0.09, 2.5 ± 2. Activation parameters (ΔH(k1)(++), kJmol(-1); ΔS(k1)(), J K(-1) mol(-1)) from Eyring plots for entering nucleophiles as indicated are as follows: fac-[Re(CO)(3)(Phen)(MeOH)](+) iodide 70 ± 1, -35 ± 3; fac-[Re(CO)(3)(2,4-dPico)(MeOH)] bromide 80.8 ± 6, -8 ± 2; fac-[Re(CO)(3)(Flav)(MeOH)] bromide 52 ± 5, -52 ± 15. A dissociative interchange mechanism is proposed., (© 2011 American Chemical Society)

The asymmetric unit of the title tetra-nuclear niobium(V) compound, [Nb(4)(C(2)H(5)O)(8)(C(5)H(7)O(2))(4)O(4)], contains two Nb(V) atoms, two bridging O atoms, two acetyl-acetonate and four ethano-late ligands. Each Nb(V) atom is six-coordinated by the bridging O atoms, two ethano-late and one chelating acetyl-acetonate ligands. The Nb-O distances vary between 1.817 (2) and 2.201 (2) Å and the O-Nb-O angles vary between 78.88 (8) and 102.78 (9)°, illustrating the significant distortion from ideal ocahedral geometry. The rest of the tetra-nuclear unit is generated through an inversion centre. The C atoms of two of the ethano-late mol-ecules are disordered over two sites [occupancy ratio 0.601 (12):0.399 (12)].

In the title compound, [RhCl(3)(CH(3)CN)(C(18)H(21)P)(2)]·2CH(3)CN, the complex mol-ecule lies on a twofold rotation axis that passes through the Rh(III) atom, one Cl atom, and the C and N atoms of the coordinated acetonitrile mol-ecule. The Rh(III) atom is coordinated by two P atoms in trans positions, three Cl atoms and an acetonitrile mol-ecule in a distorted octa-hedral geometry. Intra-molecular C-H⋯Cl inter-actions are observed. The uncoordinated acetonitrile mol-ecule is disordered over two sites with occupancies of 0.588 (4) and 0.412 (4).

The title compound, C(7)H(10)F(6)O(4), was isolated as an unexpected product from a reaction of tantalum(V) methoxide with hexa-fluoro-acetyl-acetone in a methanol solution. The asymmetric unit consists of one half-mol-ecule with the middle C atom lying on a twofold axis. The crystal structure is stabilized by O-H⋯O and an array of C-H⋯F hydrogen-bonding inter-actions. These inter-actions link the mol-ecules into a stable supra-molecular three-dimensional network. The mol-ecules pack in a ribbon-like form in the ac plane as a result of these inter-actions.

The binuclear molecule of the title compound, [Hf(2)(C(10)H(6)F(3)O(2))(6)(OH)(2)]·2C(3)H(7)NO, lies across an inversion centre and contains a Hf(IV) atom which is eight-coordinated and surrounded by three chelating β-diketonato tris-(4,4,4-trifluoro-1-phenyl-acetyl-acetonate (tfba(-)) ligands and two bridging OH(-) groups in a distorted square-anti-prismatic geometry. The Hf-O bond lengths vary from 2.073 (2) to 2.244 (2) Å and the O-Hf-O bite angles vary from 73.49 (9) to 75.60 (9)°. Weak O-H⋯O hydrogen-bonding inter-actions are observed between the bridging hy-droxy groups and the dimethylformamide solvent mol-ecules. The unit cell contains solvent-accessible voids of 131 Å(3), but the residual electron density in the difference Fourier map suggests no solvent mol-ecule occupies this void.

The title compound, C(19)H(9)N(5)O(4), has crystallographically imposed twofold rotational symmetry. The asymmetric unit contains one half-mol-ecule. The crystal structure is stabilized by π-π stacking of inversion-related pyrrolo-[3,4-b]pyridine rings, with a centroid-centroid distance between stacked pyridines of 3.6960 (8) Å. The dihedral angle between the central pyridine ring and the pyrrolo-pyridine side rings is 77.86 (2)° while the angle between the two side chains is 60.87 (2)°.

In the title compound, [Re(C(5)H(4)F(3)O(2))(C(5)H(5)N)(CO)(3)], the Re(I) atom is six-coordinated owing to bonding by three carbonyl ligands arranged in a fac configuration, two O atoms from the bidentate 1,1,1-trifluoro-acetyl-acetonate ligand and an N atom from a pyridine ligand. In the crystal, the mol-ecules pack in layers, diagonally, in a head-to-tail fashion across the ab plane. These layers are stabilsed by inter-molecular C-H⋯O and C-H⋯F hydrogen bonds.

In the title compound, [Hf(C(11)H(10)NO)(4)]·2C(3)H(7)NO, the Hf(IV) atom is coordinated by four N,O-donating bidentate 5,7-dimethyl-8-quinolino-late (Ox(-)) ligands arranged to give a distorted square-anti-prismatic coordination polyhedron. The average Hf-O and Hf-N distances are 2.098 and 2.298 Å, respectively, and the average O-Hf-N bite angle is 70.2°. The crystal packing is controlled by π-π inter-actions between Ox(-) ligands of neighbouring mol-ecules, giving rise to a three-dimensional supra-molecular grid network. The inter-planar distances vary from 3.441 (1) to 3.509 (1) Å, while the centroid-centroid distances vary from 3.688 (2) to 3.759 (12) Å. A non-classical C-H⋯O hydrogen bond is observed between the complex and one of the solvate mol-ecules.

In the title compound, Na(2)[Co(CH(4)O(6)P(2))(2)(H(2)O)(2)]·2H(2)O, the asymmetric unit is composed of one methyl-enediphospho-nate ligand and one water mol-ecule, which both are coordinated to a Co(II) atom, as well as a non-coordinated water mol-ecule and a sodium cation. The Co(II) atom occupies a special position on a crystallographic inversion centre. The slightly distorted Co(II)O(6) octa-hedral coordination environment is composed of two bidentate methyl-enediphospho-nate ligands and two coordinated water mol-ecules in trans positions. The sodium ion is octa-hedrally coordinated to six O atoms with Na-O distances ranging from 2.3149 (12) to 2.6243 (12) Å. An extensive three-dimensional network of inter-molecular as well as intra-molecular O-H⋯O and C-H⋯O hydrogen bonding inter-acions is present.

The asymmetric unit of the title compound, Cs(2)[Co(CH(4)O(6)P(2))(2)(H(2)O)(2)], is comprised of one bidentate methyl-enediphospho-nate ligand and one water mol-ecule which are coordinated to the Co(II) atom, as well as a caesium counter-cation. The Co atom occupies a special position on a crystallographic inversion center. The caesium ion is octa-hedrally coordinated by six O atoms with Cs-O distances ranging from 3.119 (2) to 3.296 (2) Å. A three-dimensional network is formed through O-H⋯O hydrogen bonds.

In the title compound, [Zr(C(6)H(4)NO(2))(4)]·2H(2)O, the Zr(IV) atom is located on a crystallographic fourfold rotoinversion axis ([Formula: see text]) and is coordinated by four picolinate anions with Zr-O and Zr-N distances of 2.120 (2) and 2.393 (2) Å, respectively. An approximate square-anti-prismatic coordination polyhedron of the N,O-coordination ligand atoms is formed, with a distortion towards dodeca-hedral geometry. The crystal packing is stabilized by inter-molecular π-π inter-actions between adjacent picolinate rings [centroid-centroid distances = 3.271 (1) and 3.640 (2) Å], as well as O-H⋯O hydrogen bonds between the solvent mol-ecules and the coordinated ligands, thereby linking the mol-ecules into a supra-molecular three-dimensional network.

In the title compound, C(28)H(27)NP(2), the N atom adopts an almost planar geometry with the two P atoms and the C atom attached to it, with a distance of 0.066 (2) Å between the N atom and the C/P/P plane. The distorted trigonal-pyramidal geometry of the N atom is further illustrated by bond angles ranging between 115.22 (11) and 123.53 (8)°. Bond angles varying from 99.99 (9) to 108.07 (9) ° are indicative of the distorted pyramidal environment around the P atoms. An intra-molecular C-H⋯P hydrogen bond occurs. In the crystal, inter-molecular C-H⋯π inter-actions link the mol-ecules into a supra-molecular network.

In the title compound, (C(8)H(20)N)[ReBr(2)(C(7)H(9)N)(CO)(3)], the Re(I) atom is octa-hedrally surrounded by three carbonyl ligands orientated in a facial arrangement, two bromide ligands and an o-toluidine ligand. The amine lies trans to the carbonyl ligand and is substitutionally disordered over two positions in a 0.66 (1):0.34 (1) ratio. An array of C-H⋯O, C-H⋯Br and N-H⋯Br hydrogen-bonding inter-actions between the cations and the surrounding rhenate anions stabilize the crystal structure.

In the title compound, (C(8)H(20)N)[ReBr(C(5)H(7)O(2))(CO)(3)], the Re(I) atom in the rhenate anion is surrounded by three carbonyl ligands orientated in a facial arrangement, a bromide ligand and an acetyl-acetonate ligand, leading to a distorted octa-hedral ReC(3)BrO(2) coordination with a O-Re-O bite angle of 85.66 (7)°. An array of C-H⋯O and C-H⋯Br hydrogen-bonding inter-actions between the cations and the surrounding rhenate anions stabilize the crystal structure.

The coordination around the N atom in the title compound, C(29)H(29)NP(2), shows an almost planar geometry, defined by the attached P and C atoms, in order to accomodate the steric bulk of the phenyl rings. The distortion of the trigonal-pyramidal geometry of the N atom is illustrated by the bond angles ranging between 115.22 (12) and 121.76 (9)°. The P atoms present a pyramidal environment with bond angles ranging from 100.62 (9) to 104.71 (8)°. One of the C atoms in the cyclo-pentyl ring displays a 0.822 (4):0.178 (4) positional disorder. Within the crystal structure, intra-molecular C-H⋯P hydrogen bonds together with inter- and intra-molecular C-H⋯π inter-actions link the mol-ecules into a supra-molecular two-dimensional network.

In the title compound, C(27)H(25)NP(2), the diphenyl-phosphino groups are staggered relative to the PNP backbone. The dihedral angles between the phenyl rings bonded to each P atom are 51.74 (5) and 68.23 (4)°. The coordination around the N atom deviates from trigonal-pyrimidal geometry towards an almost planar arrangement between the N atom and the adjacent P and C atoms; the distance between the N atom and the plane formed by the adjacent C/P/P atoms is 0.098 (2) Å.

In the title compound, (C(24)H(20)As)(2)[Co(2)(C(6)H(6)NO(6))(2)(OH)(2)]·8H(2)O, the Co(III) atom in the binuclear centrosymmetric anion is octa-hedrally surrounded by one N atom and three O atoms of the tetra-dentate nitrilo-triacetate ligand and two μ-hydroxide ligands. The crystal packing is controlled by C-H⋯O and O-H⋯O hydrogen-bonding inter-actions. The crystal employed in this study proved to be a two-component twin around (01).

In the title compound, [Hf(C(15)H(11)O(2))(4)], the Hf(IV) atom is coordinated by four 1,3-diphenyl-propane-1,3-dionato ligands with an average Hf-O distance of 2.17 (3) Å and O-Hf-O bite angles varying from 74.5 (1) to 75.02 (9)°. The coordination polyhedron shows a slightly distorted Archimedean square-anti-prismatic geometry. The crystal packing is stabilized by weak C-H⋯O inter-actions.

In the title compound, (C(8)H(20)N)[Re(C(9)H(5)N(2)O(2))Cl(CO)(3)], the Re(I) atom is coordinated facially by three carbonyl groups, the bidentate quinoxaline-2-carbaldehyde ligand and a chloride atom, forming a distorted octahedral geometry.. The crystal packing is controlled by C-H⋯O hydrogen bonding and π-π stacking inter-actions involving the benzene rings, with a centroid-centroid distance of 3.4220 (1) Å.

In the title complex, (C(5)H(6)N)[Cr(CH(4)O(6)P(2))(2)(H(2)O)(2)]·4H(2)O, the Cr(III) atom, lying on an inversion centre, is coordinated by two bidentate methyl-ene diphospho-nate ligands and two water molecules in a distorted octa-hedral coordination geometry. The pyridinium cation is located on an inversion centre, with an N atom and a C atom sharing a position each at a half occupancy. A three-dimensional network is constructed by O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds between the pyridin-ium cation, complex anion and uncoordinated water mol-ecules.

In the title compound, [Pt(C(30)H(31)NP(2))(2)](PF(6))(2)·2CH(2)Cl(2), the four-coordinated Pt(II) atom, situated on an inversion centre, exhibits a highly distorted square-planar geometry illustrated by the P-Pt-P bite angle of 70.76 (3)°. The cyclo-hexyl ring and one of the phenyl rings display 0.630 (7):0.37 (7) and 0.60 (2):0.40 (2) positional disorder, respectively. The dichloro-methane solvent mol-ecule displays 0.526 (4):0.474 (4) positional disorder. C-H⋯F hydrogen bonds stabilize the crystal packing.

The Pt(II) atom in the title compound, [Pt(C(29)H(31)NP(2))(2)](PF(6))(2)·2CH(2)Cl(2), is coordinated by four P atoms from two bis-(di-phenyl-phosphan-yl)pentyl-amine ligands with an average Pt-P distance of 2.300 (1) Å. The coordination around the Pt(II) atom shows a highly distorted square-planar geometry, as evidenced by the P-Pt-P bite angles of 70.45 (3) and 70.64 (3)°. The asymmetric unit contains two hexa-fluoridophosphate ions, the metal complex and two dichloro-methane solvent mol-ecules. One of the chloride atoms of one of the dichloro-methane mol-ecules is disordered over two sites in a 0.515 (3):0.485 (3) ratio. C-H⋯F hydrogen bonds stabilize the crystal packing.

In the title salt, (C(8)H(20)N)[ReBr(C(7)H(5)O(2))(CO)(3)], the Re(I) atom is octa-hedrally surrounded by three facially orientated carbonyl ligands, one bidendate tropolonate ligand and a bromide ligand. The small O-Re-O bite angle of 74.88 (12)° leads to a distortion of the octa-hedral coordination sphere. The bromide ligand and the axial carbonyl ligand are substitutionally disordered over two positions in a 0.922 (3):0.078 (3) ratio. An array of C-H⋯O and C-H⋯Br hydrogen-bonding inter-actions between the cations and neighbouring rhenate anions stabilizes the crystal packing.

In the title compound, [Nb(CH(3)O)(3)(C(5)H(7)O(2))Cl], the Nb(V) atom is coordinated by two O atoms from the chelating acetyl-acetonate ligand, three O atoms from the methano-late groups and one chloride ligand. The octa-hedral environment around niobium is slightly distorted with Nb-O distances in the range 1.8603 (15)-2.1083 (15) Å and an Nb-Cl distance of 2.4693 (9) Å. The O-Nb-O angles vary between 80.74 (6) and 100.82 (7)°, while the trans Cl-Nb-O angle is 167.60 (5)°. There are no hydrogen bonds observed, only an inter-molecular C-H⋯O inter-action.

In the title compound, [Hf(C(9)H(6)NO)]·C(3)H(7)NO·H(2)O, the hafnium(IV) atom is coordinated by four 8-quinolinolate (Ox) ligands, forming a slightly distorted square-anti-prismatic coordination polyhedron. The crystal packing is controlled by O-H⋯O and C-H⋯O hydrogen-bonding inter-actions and π-π inter-actions between quinoline ligands of neighbouring mol-ecules. The inter-planar distances vary between 3.150 (1) and 3.251 (2) Å, while centroid-centroid distances vary from 3.589 (1) to 4.1531 (1) Å.

The Pt(II) atom in the title compound, [PtCl(2)(C(27)H(27)NP(2))], has a highly distorted square-planar geometry, as evidenced by the P-Pt-P bite angle [72.4 (1)°]. The strain in the complex is further illustrated by the distorted tetra-hedral angles of the P atoms, which range between 93.5 (1) and 122.2 (1)°. It is of inter-est to note that the N atom has to adopt an almost planar geometry with the two P atoms and the C atom attached to it [it is displaced by 0.093 (2) Å from the CP(2) plane] in order to accommodate the steric bulk of the phenyl groups and the alkyl group of the ligand coordinated to the Pt(II) centre. The mol-ecules pack in horizontal rows across the bc plane. C-H⋯Cl hydrogen bonds stabilize the crystal packing.

The title compound, C(14)H(13)NO, is non-planar with a dihedral angle of 47.00 (6)° between the planes of the two aromatic rings. Intra-molecular hydrogen bonding is observed between the O-H group and the N atom, resulting in a phenol-imine tautomeric form.

In the title compound, [ReBr(C(27)H(27)NP(2))(CO)(3)], the Re(I) atom is octa-hedrally surrounded by three carbonyl ligands in a facial arrangement, a bromide ligand and the P,P'-bidentate ligand Bis(diphenyl-phosphino)propyl-amine. The compound exhibits substitutional disorder of the bromide ligand and the axial carbonyl ligand, with almost 50% occupancy for both Br amd CO [0.538 (4) and 0.462 (4), respectively]. In addition, the propyl chain on the N atom of the bidentate ligand exhibits a 0.648 (9):0.352 (9) disorder. C-H⋯O and C-H⋯Br hydrogen bonding consolidates the crystal packing.

In the title compound, [Hf(C(9)H(6)NO)(4)]·2C(7)H(8), the hafnium metal centre is coordinated by four N,O-donating bidentate quinolin-8-olate ligands arranged to give a square-anti-prismatic coordination polyhedron with a slightly distorted dodeca-hedral geometry. The average Hf-O and Hf-N distances are 2.096 (3) and 2.398 (3) Å, respectively, and the average O-Hf-N bite angle is 70.99 (11)°. The crystal packing is controlled by π-π inter-actions between quinoline ligands of neighbouring mol-ecules and hydrogen-bonding inter-actions. The inter-planar distances vary between 3.138 (1) and 3.208 (2) Å, while the centroid-centroid distances range from 3.576 (1) to 4.074 (1) Å.

In the title complex, (C(8)H(20)N)[Re(C(5)H(3)N(2)O(2))Cl(CO)(3)], the Re(I) atom is coordinated facially by three carbonyl groups; the bidentate pyrazine-carboxyl-ato ligand and a chlorine atom complete the distorted octa-hedral coordination.

In the salt, (NH(4))(2)[Co(CH(4)O(6)P(2))(2)(H(2)O)(2)], the methyl-ene-diphospho-nate acts as a bidentate ligand and the Co(II) ion (site symmetry ) assumes an octa-hedral CoO(6) coordination geometry. The acid H atom of the ligand is distributed over two O atoms. In the crystal, a three-dimensional network is formed through O-H⋯O and N-H⋯O hydrogen bonds between the cations and anions.

The binuclear title compound, [Hf(2)(C(5)HF(6)O(2))(6)(OH)(2)]·C(3)H(6)O, contains an Hf(IV) atom which is eight coordinated and surrounded by three chelating β-diketonato 1,1,1,5,5,5-hexa-fluoro-acetyl-acetonate (hfaa) ligands and two bridging OH groups situated on a twofold rotation axis. The HfO(8) coordination polyhedron shows a slightly distorted Archimedean square anti-prismatic coordination with average Hf-O, C-O, C-C(Me) distances of 2.19 (2), 1.26 (2) and 1.49 (2) Å, respectively, and an O-Hf-O bite angle of 75.3 (5)°. Weak O-H⋯O hydrogen bonding inter-actions are observed between one of the bridging hydr-oxy groups and the disordered solvent mol-ecule.

The title complex, [Re(C(7)H(2)Br(3)O(2))(CO)(3)(H(2)O)]·CH(3)OH, crystallized as a neutral Re(I) compound and one methanol solvent mol-ecule in the asymmetric unit. The metal centre is coordinated facially by three carbonyl groups. The bidentate tribromo-tropolanate ligand and a water mol-ecule complete the distorted octahedral coordination around the central metal. Inter-molecular Br⋯O [3.226 (5) Å] and Br⋯Br [3.590 (2) Å] contacts are observed between adjacent mol-ecules. These contacts, together with an array of O-H⋯O, O-H⋯Br and C-H⋯O hydrogen bonds, complete a three-dimensional polymeric network formed between the methanol solvent and the complex.

The asymmetric unit of the title compound, [Co(NH(3))(6)][Mn(CN)(6)], contains one Co and one Mn atom, both lying on threefold inversion axes, and one NH(3) and one CN group. The octa-hedral environments around Co(II) and Mn(II) are generated by symmetry and show very slight deviations from ideal geometry. A three-dimensional network is created by N-H⋯N hydrogen bonds.

The title compound, [Co(C(2)H(8)N(2))(3)][CoMo(CN)(8)(C(2)H(8)N(2))(2)(H(2)O)]·2H(2)O, is isostructural with the Ni(II) analogue. The Mo(IV) atom is coordinated by eight cyanide ligands, one of which forms a bridge to a Co(II) atom that is itself coordinated by two bidentate ethane-1,2-diamine (en) ligands and one water mol-ecule. Another Co(II) complex, coordinated to three bidentate en ligands, acts as the counter-ion. The crystal structure contains O-H⋯N/O, N-H⋯N/O and C-H⋯N/O hydrogen bonds, which form a three-dimensional network.

There are two mol-ecules with similar bond dimensions in the asymmetric unit of the title complex, [Re(C(7)H(4)NO(4))(CO)(3)(H(2)O)]. The metal centre is coordinated facially by three carbonyl groups, is chelated by a 4-carboxy-pyridine-2-carboxyl-ate ligand and is also coordinated by a water mol-ecule. O-H⋯O hydrogen bonds give rise to a three-dimensional network.

The diphenyl-phosphine groups in the title compound, C(29)H(31)NP(2), are staggered relative to the PNP backbone. The N atom adopts an almost planar geometry with the two P atoms and the C atom attached to it, in order to accommodate the steric bulk of the phenyl groups and the alkyl group. Three C atoms of the 1,2-dimethylpropylamine group are disordered over two positions in a 9:1 ratio. The mol-ecules pack diagonally in the unit cell across the ac plane in a head-to-tail fashion.