Martti Klinga

Pyridinylimine-based nickel(II) and palladium(II) complexes: preparation, structural characterization and use as alkene polymerization catalysts

Abstract Preparation of four dimeric nickel(II) complexes and three monomeric palladium(II) complexes bearing didentate pyridinylimine ligands is described. The solid-state structures of these compounds have been determined by single-crystal X-ray diffraction. After activation with methylaluminoxane (MAO) the nickel compounds were used as catalysts in ethylene polymerization producing nearly linear or primarily methyl-branched polymers. The effect of ligand environment was most evident on degree of branching, while catalytic activity and molecular weight of the polymer were more dependent on the general catalyst composition as well as reaction conditions. Activation of the dichloropalladium(II) complexes with MAO yields highly active catalysts for the polymerization of bicyclo[2.2.1]hept-2-ene (norbornene) whereas only low conversions (

Synthesis and X-ray Structures of New Mononuclear and Dinuclear Diimine Complexes of Late Transition Metals

Synthesis of new palladium(II) (1), nickel(II) (2a and 2b), and cobalt(II) (3) complexes bearing the unsymmetrical, bidentate nitrogen ligand 2,6-bis(1-methylethyl)-N-(2-pyridinylmethylene)phenylamine (L) is described. The solid-state structures of 1, 2a, and 2b have been determined by single-crystal X-ray diffraction. The PdII compound exists in the monomeric form whereas the nickel complexes were observed as centrosymmetric dimers with slightly distorted square-pyramidal coordination sphere around each nickel center.

SINGLY ANTI-ANTI CARBOXYLATE-BRIDGED ZIG-ZAG CHAIN COMPLEXES FROM A CARBOXYLATE-CONTAINING TRIDENTATE SCHIFF BASE LIGAND AND M(HFAC)2 M = MNII, NIII, AND CUII : SYNTHESIS, CRYSTAL STRUCTURE, AND MAGNETIC PROPERTIES

The reaction of M(hfac)2 with the tridentate Schiff base H2L (where H2L stands for the 1:1 condensation product of 2-imidazolecarboxaldehyde with β-alanine) leads to the complexes [M(HL)(hfac)]n [M = MnII, NiII, and CuII; hfac = hexafluoroacetylacetonate anion] (1–3). The structures of the complexes 1 and 3 have been solved by X-ray crystallographic methods. The structures are very similar and consist of infinite zig-zag chains, running parallel to the b axis, in which the metal ions are bridged sequentially by anti-anti carboxylate groups with intrachain metal–metal distances of 6.134 A for 1 and 6.239 A for 3. Each monodeprotonated HL ligand acts as a tridentate one to a metal(II) ion and as a monodentate one to a neighbouring metal(II) centre. Metal atoms exhibit distorted octahedral coordination spheres comprised of two oxygen atoms from the hexafluoroacetylacetonate ligand, three donor atoms from the HL ligand and the oxygen atom belonging to the carboxylate group of an adjacent molecule. The complexes 1–3 have been confirmed to be isomorphous and isostructural on the basis of X-ray powder diffraction and IR spectra. The magnetic properties of the three compounds were studied by susceptibility measurements as a function of the temperature and successfully analyzed in terms of the isotropic spin Hamiltonian for one-dimensional infinite chain systems to give the coupling parameters J = –0.91 cm−1, g = 2.03 (1); J = –13.2 cm−1, g = 2.24 (2); and J = 0.40 cm−1, g = 2.11 (3). The magnetic behaviour for all three complexes can be satisfactorily explained in terms of the conformation of the bridge and the interaction between the d orbitals of the metal centre and the bridge.

Iron and Cobalt Complexes of a Series of Tridentate P, N, P Ligands — Synthesis, Characterization, and Application in Ethene Polymerization Reactions

A series of tridentate P, N, P ligands comprising a central pyridine unit and two pendent diarylphosphane moieties (2, 6-bis(CH2PAr2)pyridine; Ar = phenyl (1), 2-methylphenyl (2), 2, 4, 6-trimethylphenyl (3)) as well as the corresponding iron (1-FeCl2, 2-FeCl2, 3-FeCl2) and cobalt (1-CoCl2, 2-CoCl2, 3-CoCl2) complexes were synthesized and characterized. An X-ray structure analysis of 2-CoCl2 and 3-CoCl2 exhibited a trigonal-bipyramidal coordination geometry at the metal center, the two chlorine atoms and the nitrogen occupying the equatorial and the phosphane units the apical positions. IR analysis indicated, that in all complexes the pyridine unit is coordinated to the metal center. The cobalt compounds were applied as catalyst precursors for the polymerization of ethene after activation with MAO. Eisen- und Cobaltkomplexe mit dreizahnigen P, N, P-Liganden — Synthese, Charakterisierung und Verwendung als Katalysatoren fur die Ethenpolymerisation Eine Reihe von dreizahnigen P, N, P-Liganden, bestehend aus einer 2, 6-diarylphosphansubstituierten Pyridineinheit (2, 6-bis(CH2PAr2)pyridin; Ar = phenyl (1), 2-methylphenyl (2), 2, 4, 6-trimethylphenyl (3)), wurde zu den entsprechenden Eisen(1-FeCl2, 2-FeCl2, 3-FeCl2) und Cobaltkomplexen (1-CoCl2, 2-CoCl2, 3-CoCl2) umgesetzt. Strukturanalysen an 2-CoCl2 und 3-CoCl2 zeigten in beiden Fallen eine trigonal-bipyramidale Koordinationsanordnung am Cobalt(II). Die Cobalt-Verbindungen wurden nach Aktivierung mit MAO als Katalysatoren fur die Polymerisation von Ethen eingesetzt.

Synthesis, crystal structure and initial biological evaluation of the new enantiomerically pure chiral palladium(II) complex trans-bis[endo-(1R)-1,7,7-trimethylbicyclo[2.2.1]-heptan-2-amino]palladium(II)dichloride.

The palladium(II) complex trans-bis[(R)-(+)-bornylamino]palladium(II) dichloride was synthesised and characterised. The solid state structure of the complex was determined by X-ray structure analysis. The compound crystallises in the monoclinic space group P2(1) with a=12.383(2), b=23.689(5), c=12.769(3) A, beta=93.25(3) degrees, and V=3739.6(13) A(3). The complex was tested for its cytotoxicity against L(929), K(562) and HeLa cell lines using the MTT assay technique. It is also tested for its anticomplementary activity using a test that detects complement proteins inhibition. These activities were compared with those of the reference standards, cisplatin, carboplatin and oxaliplatin. The significance of these results is given and discussed.

Synthesis of new chiral diimine palladium(II) and nickel(II) complexes bearing oxazoline- and myrtanyl-based nitrogen ligands. Crystal structure of the C2-symmetric complex [{(1R,2S)-inda-box}PdCl2]

Abstract A synthesis of new chiral dihalo palladium(II)-(5, 7) and nickel(II) (6, 8) complexes bearing the ligands N,N′-bis{(−)-(cis)-myrtanyl}butylene-2,3-diimine (BMDI, 3) and the conformationally constrained bisoxazoline ligand ((1R,2S)-inda-box, 4) is described. Reaction of [(TMEDA)Pd(CH3)Cl] (TMEDA: N,N,N′,N′-tetramethylethylenediamine) with 4 followed by chloride abstraction with NaB(Arf)4 in the presence of CH3CN afforded the solvent stabilized, monoalkyl complex [(4)Pd(NCCH3)(CH3)]B(Arf)4 (9) (Arf: 3,5-bis(trifluoromethyl)benzene). The solid state structure of the dichloro palladium(II) complex [{(1R,2S)-inda-box}PdCl2] (7) was determined by X-ray structure analysis.

Palladium(II) complexes bearing ethylene-bridged S∩As and S∩P donor ligands: synthesis, crystal structure and reactivity towards the polymerization of norbornene

Abstract Palladium(II) complexes of the general type [Pd(L∩L)Cl2] (4–6) and their corresponding dicationic complexes [Pd(L∩L)(NCCH3)2](BF4)2 (7–9) (L∩L=[(1-(thiomethyl)-2-(diphenylarsino)ethane] (S∩As, 1) (4, 7) [1-(thiomethyl)-2-(diphenylphosphino)ethane] (S∩P, 2) (5, 8) and [1,2-bis(diphenylphosphino)ethane] (P∩P, 3) (6, 9) have been synthesized and utilized as catalysts for the polymerization reaction of bicyclo[2.2.1]hept-2-ene (norbornene). The dichloride complexes can be activated with methylaluminoxane (MAO), while the corresponding dicationic compounds were used as single component catalysts for the polymerization reactions. Catalytic performance of the new type of catalyst can be altered by modifying the donor atoms in the bidentate ligand. The activity of the Pd(II) complexes towards the polymerization reaction increases with increasing the trans-influence of the donor atoms (P∩P>S∩P>S∩As). The influence of donor atoms on the length of the PdCl bonds was elucidated by X-ray structure analysis carried out on the palladium(II) complex [Pd(S∩As)Cl2] (4).

Chiral palladium(II) and platinum(II) complexes of diaminocyclohexane: X-ray structures of (1R,2R)-(−)-1,2-diaminocyclohexane dihydrochloride and its corresponding oxalato platinum(II) complex

Abstract The nucleophilic substitution reaction of the enantiomerically pure ligand, (1R,2R)-(−)-1,2-diaminocyclohexane [DACH] (1) with cis-bis(benzonitrile)palladium(II) dichloride [(PhCN)2PdCl2] leads to the formation of the complex [(DACH)PdCl2] (2) in a high yield. The reaction of the corresponding platinum(II) complex [(PhCN)2PtCl2] with DACH, under the same reaction conditions, surprisingly, took a different course, in which nucleophilic addition to the benzonitrile ligand occurred forming an enantiomerically pure amidine complex [(PhCNHNH(C6H10)NH2)Pt(NCPh)Cl]Cl (3), where the nitrogen ligand form a seven-membered chelate around the central atom. The aqua and oxalato derivatives of complex 2, [(DACH)Pd(H2O)2](NO3)2 (4) and [(DACH)Pd(C2O4)] (5) have also been prepared and characterized. The platinum analogue complex to 5, [(DACH)Pt(C2O4)] (6), was prepared starting from the enantiomerically pure isomer (1) and the platinum salt K2PtX4 (X=Cl, I). According to X-ray structural analysis carried out on the complex, the product does not consist of just the desired isomer, but a mixture of both the trans-l (trans-(−)-1R,2R) and trans-d (trans-(+)-1S,2S) isomers. No retention of optical isomerism was observed. The single crystal structural analysis was also carried out on the ligand N,N′-(1R,2R)-(−)-diaminocyclohexane dihydrochloride (DACH·2HCl)] (1a). The result indicates, however, that only the R,R-isomer exists in the free ligand.

Group 4 metal alkoxide complexes as catalysts for olefin polymerization

The complexation of 3-tert-butyl-2-hydroxy-5-methylbenzaldehyde I with titanium or zirconium tetrachloride yielded two classes of complexes containing either one or two didentate alkoxide ligands. The structures of three monomeric, six-co-ordinate complexes, cis-dichlorobis(3-tert-butyl-5-methyl-2-oxobenzoyl)titanium(IV)1, cis-dichlorobis(3-tert-butyl-5-methyl-2-oxobenzoyl)zirconium(IV)2 and mer-trichloro(3-tert-butyl-5-methyl-2-oxobenzoyl)(tetrahydrofuran)zirconium(IV)3 were characterized by single-crystal X-ray diffraction. Compounds I and 3 crystallize in the monoclinic space group P21 with Z= 2, compound 1 in Cc with Z= 4 and compound 2 in orthorhombic space group Pbca with Z= 8. In the presence of methylaluminooxane complexes 1–3 give homogeneous catalysts, which for the polymerization of ethylene produced high molecular weight polyethylene with a broad molecular weight distribution.

Oxygen-Containing, Asymmetric “Dual-Side” Zirconocenes: Investigations on a Reversible Chain Transfer to Aluminum

A series of new oxygen-substituted, asymmetric zirconocene dichlorides (rac-{1-[5,6-(ethylenedioxy)-2-methyl-1-η5-indenyl]-2-(9-η5-fluorenyl)ethane}zirconium dichloride (3a), rac{1-[5,6-(ethylenedioxy)-2-methyl-1-η5-indenyl]-2-(9-η5-fluorenyl)ethane}dimethylzirconium (3b) and rac-{[5,6-ethylenedioxy)-2-methyl-1-η5-indenyl](9-η5-fluorenyl)dimethylsilane}zirconium dichloride (3c)} have been prepared and their polymerization behavior was investigated in dependence of monomer concentration, temperature and catalyst activation. The presence of oxygen substituents on the indenyl ring results in a strong increase of polymerization activities and also of polymer molecular weights with decreasing Al/Zr ratio. Significantly higher molecular masses and activities were found for the dimethyl complex 3b after activation with [(C6H5)3C+][(C6F5)4B−] deriving from the absence of chain transfer to aluminum and higher concentration of active catalyst species. The mechanism of stereoerror formation of the oxygen-containing C1-symmetric catalyst was investigated by deuterium labeling studies on propene monomers. The results are discussed on the basis of a reversible chain transfer to aluminum.