Crystal Structure Of Pd Research Articles

Crystal and Molecular Structures of Bis[8-(diphenylphosphino)quinoline]palladium(II) Complexes: Pd(Ph2Pqn)2XY (XY = Cl2, Br2 or ClBF4)

Abstract The complex chloride, Pd(Ph2Pqn)2Cl2 (Ph2Pqn = 8-(diphenylphosphino)quinoline), crystallized either in yellow plates (1a: from CH2Cl2/Et2O) or in orange needles (1b: from MeOH/Et2O). The corresponding bromide, Pd(Ph2Pqn)2Br2, initially deposited as yellow block crystals (2a) from MeOH/Et2O, turned to orange prisms (2b) on standing in the mother liquor. The X-ray crystallographic analyses of 1a and 2a revealed that two Cl− and Br− anions, respectively, were located above and below the square-planar PdII coordination plane of cis(P)-[Pd(Ph2Pqn)2]2+. Although the distances of Pd···Cl (3.262(3) and 3.386(3) Å) and Pd···Br (3.432(2) and 3.505(2) Å) in 1a and 2a, respectively, were too long for a bonding interaction between PdII and X−, weak PdII···X− charge-transfer interactions seem to be responsible for the yellow colors of these crystals. In contrast, in 2b, the PdII formed an elongated square-pyramidal five-coordinate complex, [Pd(Ph2Pqn)2Br]+, with a somewhat long Pd–Br bond (3.0136(8) Å) at the apical position. The crystal structure of Pd(Ph2Pqn)2ClBF4 (4) revealed that the PdII center in 4 took an extremely distorted square-planar coordination geometry with the Pd–Cl bond of 2.375(2) Å, while one of the Ph2Pqn ligands coordinated through only P; cis(P)-[PdCl(Ph2Pqn-κP,N)(Ph2Pqn-κP)]BF4.

First bivalent palladium and platinum cyanoximates: synthesis, characterization, and biological activity.

A series of five cyanoximes (compounds having the general formula NC-C(=NOH)-R, where R is an amide or carboxylic ester group) have been synthesized and spectroscopically and structurally characterized. These are 2-cyano-2-isonitrosoacetamide (later HACO), 2-cyano-2-isonitrosothioacetamide (HTCO), 2-cyano-2-isonitrosoethylacetate (HECO), 2-cyano-2-isonitroso-N-piperidinylacetamide (HPiPCO), and 2-cyano-2-isonitroso-N-morpholinylacetamide (HMCO). A high yield method of synthesis was developed for the last two previously unknown amidocyanoximes. Variable temperature (13)C NMR studies in DMSO-d(6) solutions allowed the determination of rotational energy barriers for these two new cyanoximes. The HPiPCO and HMCO oxime molecules adopt a trans-anti configuration in the solid state according to X-ray analysis. Reactions between aqueous solutions of K(+)L(-) (L = cyanoximate anions: TCO(-), PiPCO(-), and MCO(-)) and K(2)[MCl(4)] (M = Pd, Pt) resulted in the formation of ML(2) complexes. The crystal structure of Pd(MCO)(2).DMSO was determined and showed the formation of coplanar dimeric [Pd(MCO)](2) units with 3.13 A Pd...Pd separation. The complex adopts cis geometry with anions being in the nitroso form. In the presence of bivalent Pd and Pt, ACO(-) and ECO(-) anions completely or partially hydrolyze in aqueous solutions to the dianion of 2-cyano-2-isonitrosoacetic acid (AACO(2-)). The crystal structure of the product of the hydrolysis reaction, K(2)[Pd(AACO)(2)].4H(2)O, was determined. Data revealed planar and cis geometry of the [Pd(AACO)(2)](2)(-) anion where cyanoximes are in the nitroso form and adopt a cis-anti configuration. All synthesized cyanoxime ligands and nine of their Pd(II) and Pt(II) complexes were tested in vitro on antiproliferating activity using human cervical cancer HeLa cell lines, and cisplatin as a positive control substance. Two out of the nine studied complexes, Pd(MCO)(2) and Pt(MCO), were found to be active compounds inflicting death on 28% and 16% of the cells, respectively, with 55% value for the cisplatin under the same conditions.

Synthesis and characterisation of cyclometallated palladium(ii) complexes with phosphine–carboxylate and phosphine–amide ligands

The coordination properties of hybrid phosphino-amide ligands o-Ph2PC6H4CONHR [R = iPr (a), Ph (b)] have been investigated. New cyclometallated palladium(II) complexes in which a and b act as P-monodentate ligands have been synthesised by reacting them with selected cyclometallated precursors containing bridging chloride or acetate groups. The crystal structures of the compounds [Pd(Bzq)(o-Ph2PC6H4CO–NHiPr)(Cl)] and [Pd(Phox)(o-Ph2PC6H4CO–NHiPr)(CH3COO)] (Bzq = 7,8-benzoquinolyl; Phox = 2-(2-oxazolinyl)phenyl) have been determined. Hemilability of coordinated ligand b is detected when it appears combined with certain cyclometallated backbones. A rigid P,O-chelating behaviour of the ligands, confirmed by the crystal structure determination of [Pd(Bzq)(o-Ph2PC6H4CO–NHiPr)][PF6], is observed in complexes obtained by adding stoichiometric KPF6 to [Pd(C^N)(μ-Cl)]2 compounds. The reactions of hydroxo-bridged precursors [Pd(C^N)(μ-OH)]2 with a and b afforded mononuclear derivatives in which a less common anionic P,N-binding mode is exhibited. The crystal structure of Pd(Phpy)(o-Ph2PC6H4CO–NiPr)] (Phpy = 2-phenylpyridine) is also reported. Furthermore, related compounds with phosphino-carboxylate ligands have been prepared by direct reaction between 2-(diphenylphosphinobenzoic) acid and [Pd(C^N)(μ-CH3COO)]2 precursors, and the X-ray structures of [Pd(C^N)(o-Ph2PC6H4COO)] (C^N = Bzq and Phpy) have been determined.

Crystal structures of palladium(II) and copper(II) complexes of meso-phenyl tripyrrinone

Meso-phenyl tripyrrinone ( 2), which is derived directly from N-confused porphyrin by Cu(II)-assisted oxygenolysis, can serve as a metal coordination ligand using three nitrogens and one oxygen in the core. The crystal structures of Pd(II) and Cu(II) complexes show the similar square-planar N 3O-coordination but the mode of oligomeric chains formed in the crystals by π–π stacking interaction is different: zig–zag for Cu(II) and straight for Pd(II) complex.

Photo-assisted formation of a chelating diphos ligand from PPh 3 and a cyclometallated [P(C 6H 4)(C 6H 5) 2] − ligand. Crystal structure of Pd{η 2- o-[P(C 6H 5) 2] 2(C 6H 4)}Br 2

The cyclometallated palladium compound, Pd[η 2-(C 6H 4)P(C 6H 5) 2]Br[P(C 6H 5) 3] ( 1), in the solid state by action of light, evolves to give Pd{η 2- o-[P(C 6H 5) 2] 2(C 6H 4)}Br 2 ( 2). This compound contains the diphosphine, o-[P(C 6H 5) 2] 2(C 6H 4), as chelated ligand that is formed by a couple reaction of the metallated ligand η 2-[(C 6H 4)P(C 6H 5) 2] − and the coordinated arylphosphine. A study by NMR spectroscopy confirms that the o-phenylene bridge in the diphosphine ligand in 2 comes from the metallated phosphine ligand in 1.

Monodentate and Bridging Coordination of 3,3′-Annelated 2,2′-Bipyridines in Zerovalent Palladium- and Platinum-p-quinone Complexes

Compounds of the type M(N∩N-κN)(nq)2 and M2(μ2-N∩N)(μ2-pbq)2, in which nq = 1,4-naphthoquinone, pbq = 1,4-benzoquinone, and N∩N is a monodentate or bridging ligand of the α-diimine type, were obtained from reactions of Pd(dba)2 in toluene with the 3,3′-annelated-2,2′-bipyridines: 4,5-diazafluoren-9-one (dafo) and 4,5-diazafluorene (dafe) in the presence of the appropriate p-quinone. In the corresponding reactions with 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), 2,2′-bipyrimidine (bpym), N,N′-dicyclohexyl-1,4-diaza-1,3-butadiene (chex-dab), bis[N-(o,o′-diisopropyl)phenylimino]acenaphthene (o,o′-iPr2-bian) and 5,6-dihydro-1,10-phenanthroline (dh-phen) only complexes of the type M(N∩N-κ2N)(Q) were formed (Q = nq, pbq). The structures of the complexes have been established by NMR in solution and by X-ray diffraction in the solid state; crystal structures of Pd(bpy-κ2N)(η2-pbq) (1) Pd(dafo-κN)(η2-nq)2 (14) and Pd2(μ2-dafo)(μ2,η2:η2-pbq)2 (16) have been determined. Of the ligands, dafo and dafe are the only ones apt to form complexes containing a monodentate or bridging N∩N ligand. This behaviour is ascribed to the geometrical constraints of dafo and dafe; the annelation by one carbon atom at the 3,3′-positions in these ligands causes an increase in bite angle from approximately 77° to 82°.

Photo-induced degradation of Pd 2(μ-Ph 2PCH 2PPh 2) 2(μ-CNPh)Cl 2 and Pd 2(μ-Ph 2PCH 2Ph 2) 2Cl 2, and the crystal structure of Pd 2(μ-Ph 2PCH 2PPh 2) 2(μ-CNPh)Cl 2

Spectroscopic studies of Pd 2(dppm) 2(μ-CNPh)Cl 2 ( 1) and Pd 2(dppm) 2Cl 2 show that they are light sensitive. Complete degradation of both complexes, to give a mixture of products including Pd(dppm)Cl 2, occurs within 0.5–1 h when ca. 5 × 10 −5 M solutions in dichloromethane are irradiated with a 100 W tungsten lamp. Crystal structure analysis of 1 has shown that it is tetragonal (space group P4 1, Z = 4). Cell dimensions and final R-value are: a = 21.233(2), c = 14.252(3) Å, R = 0.042 for 3892 observed reflections. A most interesting feature of 1 is a continuous channel, about 10 Å in diameter, extending along the 4 1 axis. The unusually large channel can accommodate molecules of solvent such as cyclohexane or dichloromethane. In the case of 1, uptake of solvent is readily reversible without concomitant collapse of the crystal lattice.

Crystal and molecular structure oftrans-dichlorobis(N-propylimidazole)palladium(II)

The crystal structure of Pd(N-PropIm)2Cl2 has been determined from X-ray data collected by counter methods. The compound crystallizes in the monoclinic space groupP21/n with four molecules per unit cell, the dimensions of which area=14.554(5),b=8.204(2),c=14.860(3) A,β=115.63(2)°. Full-matrix least-squares refinement gave a final R value of 0.0263 for 1913 independent observed reflections. The Pd atom is four-coordinated and is surrounded in atrans square planar fashion by two N atoms of the imidazole groups and by two Cl ions.

Reversible insertion of sulfur dioxide into palladiumpalladium bonds. The preparation and structure of Pd 2(μ-SO 2)(Ph 2PCH 2PPh 2) 2 Cl 2

Addition of sulfur dioxide to Pd 2(dpm) 2X 2, (dpm = (C 6H 5) 2PCH 2P(C 6H 5) 2, X = Cl or Br), Pt 2(dpm) 2Cl 2 or Pd 2[(C 6H 5) 2As(CH 2As(C 6H 5) 2]Cl 2 produces 1/1 adducts. The crystal structure of Pd 2(μ-SO 2)(dpm) 2Cl 2 shows two approximately planar palladium centers with coordination sites occupied by two phosphorus atoms from two bridging dpm ligands, a terminal halide ligand, and a bridging SO 2 ligand. The unit cell contains two crystallographically independent molecules. In most aspects the dimensions of the two molecules are similar. However, the ability of crystal packing forces to alter the PdPd distance (3.383 and 3.221 for the two different molecules) reflects the lack of a direct PdPd bond.