Showing papers on "Denticity published in 1987"

Dual emission from an ortho-metalated Ir(III) complex

Abstract: Several complexes of Ir(III) containing both the bidentate N-coordinating ligand 2,2'-bipyridine (bpy) and the N,C-orthometalating ligand 2-phenylpyridine (ppy) have recently been prepared; these include the two species Ir(ppy)/sub 2/(bpy)/sup +/ (A) and Ir(ppy)(bpy)/sub 2//sup 2 +/ (B). The former was prepared from the dichloro-bridged dimer, (Ir(ppy)/sub 2/Cl)/sub 2/, by modification of the procedure of Nonoyama while the latter was obtained by reaction of cis-(Ir(bpy)/sub 2/(OSO/sub 2/CF/sub 3/)/sub 2/) (CF/sub 3/SO/sub 3/) with ppy in refluxing 2-ethoxyethanol. The purity of the complexes was monitored with thin-layer chromatography using silica gel plates and 1:1:1 acetone/methanol/water mixtures for elution. Samples of the complexes used in these studies showed only one component in thin-layer chromatography. While only one isomer of B is possible, there are three possible isomers of A. Data from /sup 1/H and /sup 13/C NMR experiments indicate that A has C/sub 2/ symmetry. The NMR spectrum indicates, as does thin-layer chromatography, that only a single isomer of A is present with no detectable impurities due to a mixture of isomers. While X-ray structural data for A are lacking, structural data for related complexes suggest that A is the isomer with cisoid metal-carbon bonds and bpy metal-nitrogen bonds transoid to the metal-carbonmore » bonds and bpy metal-nitrogen bonds transoid to the metal-carbon bonds. These species were prepared in order to probe further the effects of metal-carbon bonding on energy-transfer processes and electron-transfer reactions of metal complexes. Emission spectroscopic studies reported here reveal unusual and distinct intramolecular energy-transfer behavior in these complexes. Whereas dual emission from the former is observed in glasses at 77 K, a single emission is observed in the latter.« less

Peroxo(tetraphenylporphinato)manganese(III) and chloro(tetraphenylporphinato)manganese(II) anions. Synthesis, crystal structures, and electronic structures.

Abstract: The syntheses and X-ray crystal structures of potassium cryptate (K(K222))/sup +/ salts of the (chlorotetraphenyl-porphinato)manganese(II) and (peroxotetraphenylporphinato)manganese(III) anions are reported. The complexes are prepared in THF by reaction of Mn/sup II/TPP with Cl/sup -/ and O/sub 2//sup -/, respectively. Both complexes crystallize in the space group P2/sub 1//c with four formula units per unit cell. The unit cell of the chloride complex has dimensions a = 12.834 A, b = 18.999 A, c = 23.313 A, ..beta.. = 99.02 at 133 K. The manganese is pentacoordinate, bonded to four pyrrole nitrogens and a chloride ion. The manganese atom is displaced 0.641 A from the least-squares plan based on the four pyrrole nitrogen atoms in the direction of the chloride ligand. The unit cell of the manganese(III)-peroxo complex has dimensions a = 12.895 A, b = 18.836 A, c = 23.045 A, ..beta.. = 99.17 at 133 K. The manganese is bonded to four pyrrole nitrogens and the bidentate peroxo ligand. The manganese lies 0.764 A above the least-squares plane based on the pyrrole nitrogens toward the peroxo ligand. The O-O bond distance is 1.421 A, and the Mn-O distances are 1.901 and 1.888 A. The peroxo ligand is bound side-onmore » to the manganese, eclipsing two of the manganese-pyrrole nitrogen bonds.« less

Copper(I) complexes with bidentate tertiary phosphine ligands: solution chemistry and antitumor activity

Abstract: Synthese des complexes [Cu(dppey) 2 ]Cl et [Cu(dppp) 2 ]Cl ou appey=Ph 2 PCH=CHPPh 2 et dppp=Ph 2 P(CH 2 ) 3 PPh 2 . Donnees RMN de 1 H et 31 P. Activite anticancereuse

Polymerization of carbon monoxide/olefin with P ligand having polar aryl group

Abstract: A polymerization process for the production of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon employs a catalyst composition formed from a palladium compound, the anion of certain non-hydrohalogenic acids and certain bidentate ligands having ortho polar substitution within at least one monovalent phosphorus substituent and optionally a quinone. The polymer product is obtained in the form of globules.

Technetium(V) and rhenium(V) complexes with N-(2-mercaptophenyl)salicylideneiminate. Crystal structure of chloro(oxo)[N-(2-sulphidophenyl)salicylideneiminato-NOS]technetium(V)

Abstract: The reactions of the tridentate Schiff-base ligand derived from salicylaldehyde and o-aminothio-phenol (H2L1) with [MOCl4]–(M = Tc or Re) have been investigated. The complexes [MOCl(L1)], [ReOCl2(L1)]–, and [ReOCl(X)(L1)](X = MeOH or EtOH) were synthesized and characterized by elemental analysis, i.r., 1H n.m.r., and u.v.–visible spectroscopy, mass spectrometry, magnetic susceptibility, conductivity, and thermogravimetric measurements and the complete configurations of the complexes were determined. X-Ray crystallographic investigation on [TcOCl(L1)] shows the molecular structure to be a distorted square pyramid having the ligand L1 in the equatorial plane with respect to TcO. The molecule is in the monoclinic space group P21/a, with a= 14.255(9)b= 12.495(7), c= 7.865(6)A, β= 105.22(5)°, and Z= 4. The structure has been refined to R= 0.068 for 2 184 observed reflections. The reactions of [MOCl(L1)](M = Tc or Re) or [ReOCl(X)(L1)](X = MeOH or EtOH) with the bidentate Schiff-base ligands (HL) salicylideneimine (HL3), N-methylsalicylideneimine (HL4), N-phenylsalicylidene-imine (HL5), N-(2-hydroxyphenyl)-p-nitrobenzylideneimine (HL6), quinolin-8-ol (Hquin), quinoline-8-thiol (Htquin), and N-(2-mercaptophenyl)-p-nitrobenzylideneimine (HL7) lead to the ‘mixed’ compounds [MO(L1)(L)]. The products with L = tquin or L7 were obtained only for [ReOCl(X)(L1)](X = MeOH or EtOH). All these complexes were characterized by the physicochemical techniques listed above.

Ternary complexes in solution. Part 49. Intramolecular equilibria in metal ion complexes of adenosine 5'-triphosphate (ATP4-): coordination of ammonia or imidazole to M(ATP)2- releases N-7 from the metal ion coordination sphere

Abstract: On montre par RMN de 1 H que par formation de complexes ternaires avec NH 3 ou imidazole, N-7 est libere de la sphere de coordination des ions metalliques; d'ou par exemple, liberation du reste adenine

The syntheses and the X-ray crystal structure of tetramethyl-ammonium tetrakis-and tris(thiocyanato)cadmates(II), [(CH3)4N]2[Cd(SCN)4] and [(CH3)4N][Cd(SCN)3]

Abstract: The crystal and molecular structure of the two new thiocyanatocadmate(II) complexes indicated in the title were determined by the single-crystal X-ray-diffraction technique. [(CH3)4N]2[Cd(SCN)4] is tri-clinic, with a space group of P\bar1; a=7.300(2), b=13.019(4), c=5.8920(9) A, α=96.32(2), β=93.080(18), γ=104.63(2)°, and Z=1, while [(CH3)4N][Cd(SCN)3] is orthorhombic with a space group of Pna21; a=10.506(3), b=13.797(5), c=9.4506(18) A, Z=4. In both complexes, the cadmium atom is in an octahedral geometry. In 1, the metal atom is at the center of symmetry, and respective pairs of side-by-side metal atoms are bridged by two thiocyanate (SCN) ions, where one SCN ion is S-coordinated and the other is N-coordinated to the same-side metal atom. Also bonded with two nitrogen atoms of unidentate SCN ions, the metal atom is 4N2S-hexa-coordinated, and they line up along the c-axis in a polymeric form. In 2, respective pairs of side-by-side metal atoms are bridged by three SCN ions, two of those SCN ions being S-c...

Synthesis and characterization of the binuclear complex di-µ-oxo-bis[N,N′-bis(2-methylpyridyl)ethane-1,2-diamine]dimanganese(III,IV)perchlorate trihydrate,[(bispicen)MnO]2(ClO4)3·3H2O

Abstract: The title complex, a new binuclear di-µ-oxo complex of manganese-(III) and -(IV) with a single tetradentate ligand in place of the previously reported bidentate bpy or phen ligands, has been synthesised and characterised by X-ray crystallography and cyclic voltammetry.

Preparation and reactivity of tricarbonyl(.eta.5-cyclopentadienyl)(organothiolato)tungsten complexes with potentially chelating thiolate ligands

Abstract: Preparation par reaction photochimique de (η 5 -C 5 H 5 ) 2 W 2 (CO) 6 avec des disulfures organiques. Structure cristalline de (η 5 -C 5 H 5 )W(CO) 3 S(CNC 6 H 4 S)

Metal ion-bridged intramolecular stacking interaction between the tryptophyl residue and the aromatic heterocyclic amine within the ternary complex (1,10-phenanthroline)(L-tryptophanato-O,N)copper(II) perchlorate–water (1/2.5): an X-ray study

Abstract: The crystal and molecular structure of [Cu(L-TrpO)(phen)] ClO4·2.5H2O has been determined by X-ray diffraction methods. The copper(II) centre is five-co-ordinate. The four equatorial sites are occupied by a bidentate tryptophanato (TrpO) ligand through a carboxylate oxygen [1.93(1)A] and an amino nitrogen [2.02(1)A] and a bidentate 1, 10-phenanthroline (phen) ligand [average 2.00(1)A]. The axial position is occupied by another carboxylate oxygen [2.29(1)A] of a symmetry-related neighbouring tryptophanato molecule. Thus a one-dimensional polymeric structure is formed with an infinite (–metal–carboxylate–)n spiral from which tryptophyl indole and phen rings project outwards and stack on each other. An indole–phen π–π interaction in the metal ion-bridged stacked folded molecular unit (average spacing 3.51 A and a tilt angle between the planes of 5°) reflects the significant deviation of the Cα atom [0.74(2)A] from the co-ordination plane and a small angle (18°) between the co-ordination and indole planes. The complex further involves metal–indole ring edge-on close contacts [3.22(2) and 3.24(2)A]. This is the first crystal structure providing direct evidence for the existence of a metal ion-bridged stacking adduct containing an aromatic amino acid residue.

Process for the selective preparation of alkenecarboxylic acid derivatives

Abstract: A process for the selective carbonylation of conjugated dienes in the presence of a hydroxyl group containing compound such as water, alcohol, phenol or carboxylic acid, in the liquid phase, characterized in that this carbonylation is carried out in the presence of a specific substantially organic nitrogen-containing base-free catalyst system, that can be formed by the combination of (a) a palladium compound and (b) at least one multidentate organic phosphorus ligand.

Cyclopalladation to form planar tridentate [N–C–N]– intramolecular co-ordination systems involving pyridine donor groups, including ligand synthesis and X-ray structural studies

Abstract: Reaction of palladium(II) acetate with 1,3-bis[1-(pyridin-2-yl)ethyl] benzene and 1,3-bis(2-pyridinecarbonyl) benzene results in cyclopalladation and formation of 2,6-bis[1-(pyridin-2-yl)ethyl] phenyl and 2,6-bis( 2-pyridinecarbonyl)phenyl complexes [Pd{(NC5H4CHMe)2C6H3}(O2CMe)]·1.5H2O (1) and [Pd{(NC5H4CO)2C6H3}(O2CMe)](4), respectively. X-Ray crystallographic studies reveal square-planar co-ordination and unidentate acetate groups, with tridentate [N–C–N]– intramolecular co-ordination involving two six-membered [graphic omitted] palladocycle rings. Proton n.m.r. spectra of complex (1) and its chloro-derivative [Pd{(NC5H4CHMe)2C6H3}Cl](2) indicate the presence of meso and rac diastereoisomers, but the crystal of (1) used for X-ray study contained the meso form only [monoclinic, space group C2/c with a= 26.08(1), b= 11.093(6), c= 15.846(7)A, β= 116.19(3)°, and Z= 8; R= 0.042 for 2 909 ‘observed’ reflections]. Crystals of (4) contain two molecules in the asymmetric unit, with the molecules having different conformations of the tridentate ligand [monoclinic, space group Pc with a= 11.373(6), b= 10.925(6), c= 15.640(10)A, β= 116.98(4)°, Z= 4; R= 0.043 (both chiralities) for 2 677 ‘observed’ reflections]. Syntheses of the new ligands are described.

Lewis base adducts of lead(II) compounds. I: Polymer isomerism in some 1:2 adducts of lead(II) halides with pyridine bases

Abstract: Recrystallization of lead(II) halides, PbX2 (X = C1, Br, I), from n- methylpyridine, n = 3, 4, yields crystalline 1 : 2 adducts; these have all been shown by single-crystal X-ray structure determination to contain the lead in an essentially octahedral six-coordinate environment, two of the coordination sites being occupied by monodentate pyridine base moieties and four by bridging halogen, yielding infinite polymeric arrays. For X = Cl, Br, n = 3, the nitrogen atoms lie cis in the coordination sphere; for the other complexes, they are trans. In the two cis complexes, distortion from ideal orthogonal geometry is more substantial than in the trans, possibly indicative of the presence of a sterically active 'lone pair'.

Solvent, ligand, pressure, and temperature effects on charge-transfer spectra of tetracarbonylmolybdenum(0) diimine complexes

Abstract: The solvent, pressure, and temperature-dependence of the lowest energy metal-to-ligand charge-transfer absorption bands are reported for a series of [Mo(CO)4(LL)], compounds where LL is a bidentate diimine ligand containing the chelating fragment −N=CRCR=N−, and one terdentate ligand analogue [Mo(CO)3(LLL)] The effects of ligand nature on these dependences are discussed, as are their interrelations and their connection with solvent properties such as polarity