Heteroleptic platinum(II) and palladium(II) complexes with thiacrown and diimine ligands

We wish to report the synthesis, crystal structures, spectroscopic and electrochemical properties of several new Pt(II) heteroleptic complexes containing the thiacrown, 9S3 (1,4,7-trithiacyclononane) with a series of substituted phenanthroline ligands and related diimine systems. These five ligands are 5,6-dimethyl-1,10-phenanthroline(5,6-Me₂-phen), 4,7-dimethyl-1,10-phenanthroline(4,7-Me₂-phen), 4,7-diphenyl-1,10-phenanthroline(4,7-Ph₂-phen), 2,2′-bipyrimidine(bpm), and pyrazino[2,3-f]quinoxaline or 1,4,5,8-tetraazaphenanthrene(tap). All complexes have the general formula [Pt(9S3)(N₂)](PF₆)₂ (N₂ = diimine ligand) and form similar structures in which the Pt(II) center is surrounded by a cis arrangement of the two N donors from the diimine chelate and two sulfur atoms from the 9S3 ligand. The third 9S3 sulfur in each structure forms a longer interaction with the platinum resulting in an elongated square pyramidal structure, and this distance is sensitive to the identity of the diimine ligand. In addition, we report the synthesis, structural, electrochemical, and spectroscopic properties of related Pd(II) 9S3 complex with tap. The ¹⁹⁵Pt NMR chemical shifts for the six Pt(II) complexes show a value near −3290 ppm, consistent with a cis-PtS₂N₂ coordination sphere although more electron-withdrawing ligands such as tap show resonances shifted by almost 100 ppm downfield. The physicochemical properties of the complexes generally follow the electron-donating or withdrawing properties of the phenanthroline substituents.     

1H n.m.r. studies of palladium(II) complexes of 2,9-dimethyl-1,10-phenanthroline and 8-hydroxyquinoline

Summary The structures in solution of a series of palladium(II) complexes have been determined by¹H n.m.r. and i.r. spectroscopy. Dicyanobis-(8-hydroxyquinoline)palladium(II) has acis-square-planar configuration, the unidentate 8-hydroxyquinoline molecules bonding to Pd through the nitrogen atoms. Dicyanobis-(2,9-dimethyl-1,10-phenanthroline)-palladium(II) has acis-square planar arrangement about Pd with respect to the nitrogen atoms of the two heterocyclic ligands. The cyanide groups bond to the two apical positions apparently giving rise to a six-coordinate PdlI atom. Dihalo-2,9-dimethyl-1,10-phenanthrolinepalladium(II) (X = Cl, Br, I) exhibits the usualcis-square-planar arrangement of Pd^II, whereas the halobis-(2,9-dimethyl-1,10-phenanthroline) - palladium(II) ion (X = Cl, Br) has a trigonal bipyramidal structure with the halogen atom in the trigonal plane.     

Synthesis,characterization, DNA binding studies and in vitro cytotoxicity of platinum(II)-dihalogenido complexes containing bidentate chelating N-donor ligands

Platinum(II) complexes, [Pt(L_x)X₂] (1–6), where X = Br or I and L_x = 2,2′-bipyridine or 1,10-phenanthroline derivatives (5,5′-dimethyl-2,2′-bipyridine (5-Mebpy), 4,4′-dimethyl-2,2′-bipyridine (4-Mebpy), and 5-amino-1,10-phenanthroline (5-NH₂phen)) were prepared. The complexes were characterized by the elemental analysis, mass spectrometry, infrared, and multinuclear (¹H, ¹³C and ¹⁹⁵Pt) 1-D and 2-D NMR spectroscopies, and by single-crystal X-ray analysis of [Pt(4-Mebpy)I₂] (4). All the platinum(II) complexes (1–6) were evaluated for in vitro cytotoxicity against human cancer cell lines A2780 and A2780R, and against non-malignant MRC5 cell line. All the complexes were nontoxic up to the 50 μM concentration, although they were found to readily bind to calf-thymus DNA (CT-DNA), as determined by spectrophotometric titration (K_b ≈ 10⁷ M^?1) and ethidium bromide displacement assay.     

Polystyrene anchored rhodium (I) bidentate ligand complexes as catalysts for hydrogenation

Polystyrene supported Rh(I) AA′ (AA′ = anthranilic acid, 2,2′-bipyridine or 1,10-phenanthroline) complexes catalyse the hydrogenation of monoolefins (terminal, cyclic and internal) and dienes. Ethyl sorbate undergoes saturation via the monoene intermediate. Thiscis olefin reacts faster than thetrans isomer. The rate law for the reaction is: Rate α [catalyst] [substrate] [H₂].     

Darstellung und katalytische Eigenschaften von Rhodium(I)-Komplexsalzen des Typs [Rh(COD)o-Py(CH2)2P(Ph)(CH2)3ZR)]PF6 (Z = O,NH)

Preparation and Catalytic Properties of Rhodium(I) Complex Salts of the Type [Rh(COD)(o-Py(CH₂)₂ P(Ph)(CH₂)₃ZR)]PF₆ (Z = O, NH) . In dichloromethane solutions were reacted [Rh(COD)Cl]₂ (COD = cis,cis-1.5-cyclooctadiene) with each of the four new ligands of the type o-Py(CH₂)₂P(Ph)(CH₂)₃ZR in the presence of the halogen scavenger TIPF₆ at 0°C to complex salts [Rh(COD) (o-Py(CH₂)₂P(Ph)(CH₂)₃ZR]PF₆ (ZR = OC₂H₅, I ; OPh, II ; NHPh, III ; NHcyclo? C₆H₁₁, IV ). The Rh¹ complex cation in the obtained compounds I – IV coordinates besides the bedentate COD group the ligand donor atoms P und pyridinic N and the remaining donor atom Z is uncoodinated in an assumed square planar ligand geometry at the Rh central atom. In 1.4 dioxane solutions the complex catalysts I – IV polymerize at 25°C the substrate phenylacetylene (PA) to polyphenylacetylene (PPA): values of TON [h^?1] between 352 ( I ) and 876 ( IV ), and average molecular weights M_w (GPC measurements) between 238 000 ( I ) and 199 900 ( IV ). These given values exhibit a dependency on the ZR group in complexes I – IV . The microstructure of isolated PPA is cis-transoidal. It is formed stereospezific and, based on MNDO calculations, is thermodynamically favoured. For the purpose of comparison, from both the newly synthesized compounds of the type [Rh(COD)DBN- (or DBU)Cl] (DBN = 1.5-Diazabi-cyclo[4.3.0.]non-5-en, DBU = 1.8-Diazabicycl0[5.4.0]- undec-7-en) was obtained a larger value of TON with 1292 (or 1327) [h^?], but a lower value of M, with 166200 (or 131200). These catalysts including I –IV polymerize PA to PPA at a lower reaction temperature with improved selectivity and larger values of M_w as hitherto known catalyst systems.     

Carbonylrhodium(I) complexes with heterocyclic nitrogen compounds

Crystalline complexes of rhodium(I) of the type [Rh(CO)₂(NN)] [RhX₂-(CO)₂] (NN  2,2'-bipyridyl, 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, 4,7-dipheynl-1,10-phenanthroline; X = Cl, Br) have been prepared. An ionic chain-like structure involving metal-metal interactions has been established by measurement of the reflectance spectra, absorption electronic spectra and electrical conductivities. The IR spectra have been examined over the 50–4000 cm^-1 range.     

Bimetallic bis(diphenylphosphino)acetylene bridged copper(I) complexes with 1,10-phenanthroline derivatives: synthesis,crystal structure,and spectroscopic characterization

A new series of bimetallic bis(diphenylphosphino)acetylene-bridged copper(I) 1,10-phenanthroline complexes, [Cu₂(dppa)₂(L)₂](BF₄)₂; L?=?1,10-phenanthroline (1); 4-methyl-1,10-phenanthroline (2); 4,7-dimethyl-1,10-phenanthroline (3); and 2,9-dimethyl-1,10-phenanthroline (4), have been prepared and characterized by spectroscopic methods. The X-ray structures of 1 and 4 were determined. The structures consist of centrosymmetric bimetallic 10-membered chair-like dimetallacycles. In 1, intermolecular C–H?π interactions result in bending of the phenanthroline ligand and sterically induced lengthening of one Cu–P bond. In 1–4, the ³¹P NMR downfield coordination shift, relative to the free ligand, correlates with the basic strength of the 1,10-phenanthroline ligands.     

Catalytic polymerization of phenylacetylene by cationic rhodium and iridium complexes of ferrocene-based ligands

Some new Rh(I) and Ir(I) complexes of the types [(COD)M(LL)]ClO₄ and [(COD)MCl]₂ [COD = cyclooctadiene; M = Rh, Ir; LL = 1,1′-bis(diphenylphosphino)ferrocene (DPPF), 1-diphenylphosphino-2-(N,N-dimethylamino)methylferrocene (FcNP), 1,6-diferrocenyl-2,5-diazahexane (FcNN)] were prepared, and their catalytic activities toward polymerization of phenyl acetylene were examined. The rhodium complexes proved to be very effective catalysts to yield highly stereoregular polyphenylacetylene (cis-transoidal-PPA) in high yields under mild conditions. The number-average molecular weight (M _n) of the PPA obtained is in the range of 19,000–33,000 and the weight-average molecular weight (M _ω) is in the range of 47,000–95,000. Comparative studies revealed that of various catalysts employed, the cationic mononuclear [Rh(FcNN)(COD)]ClO₄ complex exhibited the best results to give exclusively the cis-transoidal-PPA (cis content ∼100%) with the highest molecular weight (M _n = 33,340) in the highest chemical yield (94%). Other reaction parameters such as the softness of the ligand, the solvent, the relative amount of catalyst, and the reaction temperature were also investigated to find that all these factors played crucial roles. The iridium systems worked better for the trimerization rather than polymerization to yield 1,3,5-triphenybenzene as major product. © 1996 John Wiley & Sons, Inc.     

Rhodium(I) carbonyl complexes with heterocyclic and nonheterocyclic nitrogen-donor ligands

Summary Complexes of the [Rh(N-N)(CO)₂][RhCl₂(CO)₂], [Rh(N-N)(CO)₂]BF₄ and Rh(N-N)(CO)₂Cl types where (N-N) = 2,9-dimethyl-1,10-phenanthroline (Me₂Phen), 4,7-diphenyl-1,10-phenanthroline (Ph₂Phen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (Me₂2Ph₂Phen) or 2,2-biquinoline (biq), have been prepared and investigated. Benzidine (benz) ando-tolidine (tol) also form complexes of the first type. The complexes of the first two types behave as 11 electrolytes. While Ph₂Phen forms the four coordinate monocarbonyl Rh(Ph₂Phen)(CO)Cl complex, benzo(f)-quinoline (Q) yields the Rh(CO)₂ (Q)Cl compound. Triphenyl-phosphine and triphenylarsine react with the above complexes to form the well knowntrans-Rh(CO)ClL₂ where L = PPh₃ or AsPh₃. The i.r. and u.v.-visible spectra of the compounds are discussed.     

Effect of the ancillary ligands on the binding of ruthenium(II) complexes [Ru(dmp)2(MCMIP)]2+ and [Ru(dmb)2(MCMIP)]2+ with DNA

Two polypyridine ruthenium(II) complexes, [Ru(dmp)₂(MCMIP)]²⁺ (1) (MCMIP = 2-(6-methyl-3-chromonyl)imidazo[4,5-f][1,10]-phenanthroline, dmp = 2,9-dimethyl-1,10-phenanthroline) and [Ru(dmb)₂(MCMIP)]²⁺ (2) (dmb = 4,4′-dimethyl-2,2′-bipyridine), have been synthesized and characterized by elemental analysis, ES-MS and ¹H NMR. The DNA-binding behaviors of these complexes were investigated by electronic absorption titration, fluorescence spectroscopy, viscosity measurements and thermal denaturation. The results show that 1 and 2 effectively bind to CT-DNA; the DNA-binding affinities are closely related to the ancillary ligand.     

Effect of heterocyclic diimine ligands with donor and acceptor substituents on the spectroscopic and electrochemical properties of Au(III) complexes

The composition, structure, and properties of a series of Au(III) complexes with heterocyclic diimine ligands [Au(N^N)Cl₂]⁺, where (N^N) = 2,2′-bipyridine (Bipy), 4,4′-dimethyl-2,2′-bipyridine (DmBipy), 2,2′-biquinoline (Bqx), 1,10-phenanthroline (Phen), 2,9-dimethyl-1,10-phenanthroline (DmPhen), and 4,7-diphenyl-1,10-phenanthroline (DphPhen), were characterized by ¹H NMR, electronic absorption, and emission spectroscopy and also by cyclic voltammetry. The influence of donor and acceptor substituents on the spectroscopic and electrochemical properties of the Au(III) complexes was revealed.     

Synthesis and characterization of manganese(II), nickel(II), copper(II) and zinc(II) Schiff-base complexes derived from 1,10-phenanthroline-2,9-dicarboxaldehyde and 2-mercaptoethylamine

The synthesis of a new Schiff base containing 1,10-phenanthroline-2,9-dicarboxaldehyde and 2-mercaptoethylamine is described. The reaction of 1,10-phenanthroline-2,9-dicarboxaldehyde with 2-mercaptoethylamine leads to 2,9-bis(2-ethanthiazolinyl)-1,10-phenanthroline (I) which undergoes rearrangement when reacted with manganese, nickel, copper or zinc ions to produce complexes of the tautomeric Schiff base 2,9-bis[2-(2-mercaptoethyl)-2-azaethene]-1,10-phenanthroline (L). The [M(L)Cl₂] complexes [where M = Mn(II), Ni(II), Cu(II) and Zn(II) ions] were characterized by physical and spectroscopic measurements which indicated that the ligand is a tetradentate N₄ chelating agent.     

Metal and Substituent Influence on the Cytostatic Activity of Cationic Bis-cyclometallated Iridium and Rhodium Complexes with Substituted 1,10-Phenanthrolines as Ancillary Ligands

Synthesis and characterization of the new cyclometalated complex salts [Rh(ptpy)₂(5.6-dimethyl-1,10-phenanthroline)]PF₆ ( 1a ) [Rh(ptpy)₂(2.9-dimethyl-4.7-diphenyl-1,10- phenanthroline)]PF₆ ( 2a ), [Rh(ptpy)₂(5-amino-1,10-phenanthroline)] PF₆ ( 3a ), and [M(ptpy)₂ (pyrazino-[2.3-f]-1,10-phenanthroline)]PF₆ (M = Rh, 4a ; M = Ir, 4b ), (ptpy = 2-(p-tolyl)pyridinato) are described. The molecular structures of compounds 1b and 4a in the solid state were determined by single-crystal X-ray diffraction. All these compounds and their already known Iridium counterparts 1b – 3b display significant cytotoxicity against human cancer cell lines MCF-7 (human breast adenocarcinoma) and HT-29 (colon adenocarcinoma) with IC₅₀ values in the low micromolar range.     

Synthesis and magnetic properties of chloroanilato-bridged manganese(II) binuclear complexes

Five chloroanilato-bridged manganese(II) binuclear complexes, [Mn₂(CA)L₄](ClO₄)₂, where L = 4,4′-dimethyl-2,2′-bipyridine (Me₂-bpy), 5-methyl-1,10-phenanthroline (Me-phen), 5-chloro-1,10-phenanthroline (Cl-phen), 5-nitro-1,10-phenanthroline (NO₂-phen) and 2,9-dimethyl-1,10-phenanthroline (Me₂-phen), and CA represents the dianion of chloroanilic acid, have been synthesized and characterized by elemental analyses, molar conductivity and room temperature magnetic moment measurements, and by spectroscopy. It is proposed that these complexes have CA-bridged structures and consist of two manganese(II) ions in a distorted-octahedral environment. The complexes [Mn₂(CA)(Me₂-bpy)₄](ClO₄)₂ (1) and [Mn₂(CA)(Me-phen)₄](ClO₄)₂ (2) were characterized by variable temperature magnetic susceptibility measurements (4–300 K) and the observed data were successfully simulated by an equation based on the spin Hamiltonian operator, Ĥ = −2JŜ ₁ Ŝ ₂, giving the exchange integral J = −1.98 cm⁻¹ for (1) and J = −2.41 cm⁻¹ for (2). This result indicates that there is a weak antiferromagnetic spin-exchange interaction between the two Mn^II ions within each molecule. This revised version was published online in June 2006 with corrections to the Cover Date.     

The coordination chemistry of simple phospholes. Complexes of rhenium,ruthenium, cobalt,rhodium and iridium chlorides and of some chlorocarbonyls of ruthenium and rhodium

The reactions of 1-phenylphosphole (PP), 3-methyl-1-phenylphosphole (mPP), 3,4-dimethyl-1-phenylphosphole (dPP) and, in certain instances, 1-n-butyl-3,4-dimethylphosphole (dBP) with some transition metal chlorides and some metal-Cl-CO systems are reported. These reactions show that simple phospholes in general unexpectedly behave much like ordinary tertiary phosphines and that, unlike the reactions with Ni(II), Pd(II) and Pt(II), the complexes formed are conventional in most respects. However, a few unusual reactions were observed. For example, mPP partially reduces Ru(III) to give a mixed-valent Ru(III)-Ru(II) complex while PP reduces Ir(III) to Ir(I). From infrared spectroscopic studies of the square-planar Rh(I) complexes L₂Rh(CO) Cl (L = phosphole), it appears that donor character decreases with decreasing substitution on the phosphole ring carbon atoms. Phosphorus-phenyl cleavage has been observed in reactions of 1-phenylphosphole with Rh-CO systems. The results are briefly discussed in relation to the behaviour of other phospholes in similar reactions and in the context of the electronic structure of phospholes.     

Transition-Metal Complexes with Nano-Sized Phosphine and Pyridine Ligands-Catalysis,Fluxional Behavior and Molecular Recognition

Nano-sized phosphine and pyridine ligands having tetraphenylphenyl-, m-terphenyl-, poly(benzylether) moieties were synthesized. These ligands showed a remarkable effect on homogeneous transition metal catalyzed reactions. Pd(II) complexes with tetraphenylphenyl substituted pyridine ligands show high catalytic activities for oxidation of ketones suppressing Pd black formation and maintains the catalytic activity for a long time. Rh(I) complex catalysts with m-terphenyl substituted phosphine ligands showed remarkable rate acceleration in the hydrosilylation of ketones. In addition, several phosphinocalixarene ligands were synthesized and their coordination studies with Pd(II), Pt(II), Ru(II), Ir(I), and Rh(I) metals were documented. Ir(I) and Rh(I) cationic complexes with a 1,3,5-triphosphinocalix[6]arene ligand showed dynamic behavior with size-selective molecular recognition.     

Solvent effects on the redox properties of tris-(1,10-phenanthroline)iron(II/III) complexes

The redox properties of the system Fe(tmphen)₃(II/III) (tmphen=3,4,7,8-tetramethyl-1,10-phenanthroline) have been studied in the solvents nitromethane, acetonitrile, propanediol-1,2-carbonate, dimethylformamide, dimethylacetamide, dimethylsulfoxide and of the systems Fe(phen)₃(II/III) (phen=1,10-phenanthroline) and Fe(niphen)₃(II/III) (niphen=5-nitro-1,10-phenanthroline) in the solvents nitromethane, acetonitrile, propanediol-1,2-carbonate and acetone. The redox potentials of Fe(tmphen)₃(II/III) are nearly independent of the solvent suggesting that the system might be used as a reference redox couple similar to the systems ferrocene/ferricinium or bisbiphenylchromium(0/I). In contrast the redox potentials of Fe(niphen)₃(II/III) show a significant decrease with increasing donor number of the solvent which can be explained by nucleophilic attack of solvent molecules at the iron. It is shown that such a mechanism is consistent with the known solvent and salt effects on the kinetics of dissociation of ferroin and ferriin type complexes.     

Preparations and properties of vanadium(III) complexes of bidentate and terdentate nitrogen-donor ligands

Summary Vanadium(III) chloride reacts with 1,10-phenanthroline and 2,2-bipyridyl, and with substituted derivatives of each ligand (B), in ethanol or in acetonitrile as solvent (L), to yield two different series of complexes. These are (a) the neutral species VCl₃BL, where B = 1,10-phenanthroline, 5-chloro-1,10-phenanthroline, 5-methyl-1,10-phenanthroline, 4,7-dimethyl-1,10-phenanthroline, 2,2-bipyridyl, 4,4-dimethyl-2,2-bipyridyl, L = ethanol. The complexes in which B = 1,10-phenanthroline or 2,2-bipyridyl were also obtained with L = acetonitrile, (b) [VCl₂B₂]⁺[VCl₄B]^– where B is the same series of ligands listed above. Vanadium(III) chloride yields VCl₃ (terpy) with 2,2,2 -terpyridyl. All the complexes have been characterised by elemental analyses, conductance measurements, electronic- and i.r. spectral measurements, and by their temperature-range (297–77 K) magnetic moments; ring substituents have little influence on any chemical or physical properties of these complexes.     

Synthesis, structure and luminescence property of the ternary and quaternary europium complexes with furoic acid

A ternany europium complex with furoic acid (α-FURA) and 1,10-phenanthroline(phen), [Eu(α-FURA)₃phen]H₂O(I) and a quaternary europium furoate complex with 1,10-phenanthroline and nitrate, Eu(α-FURA)₂NO₃phen(II) were synthesized and characterized by X-ray diffraction. The two europium ions in each of the complexes (I) and (II) are held together by four carboxylato groups with the two modes, namely bidentate bridging and tridentate bridging, and each europium ion is further bonded to two nitrogen atoms from 1,10-phenanthroline and one chelated bidentate furoate group for the complex (I) and one chelated nitrato group for the complex (II), making a coordination number of 9. Luminescence spectra observed at 77 K show that the europium ion site in the crystals of the complexes (I) and (II) has low symmetry and lifetimes of the solid complexes (I) and (II) are 1.13 and 1.20 ms, respectively.     

Rhodium and iridium complexes of N-heterocyclic carbenes: Structural investigations and their catalytic properties in the borylation reaction

Bridged and unbridged N-heterocyclic carbene (NHC) ligands are metalated with [Ir/Rh(COD)₂Cl]₂ to give rhodium(I/III) and iridium(I) mono- and biscarbene substituted complexes. All complexes were characterized by spectroscopy, in addition [Ir(COD)(NHC)₂][Cl,I] [COD = 1,5-cyclooctadiene, NHC =  1,3-dimethyl- or 1,3-dicyclohexylimidazolin-2-ylidene] (1, 4), and the biscarbene chelate complexes 12 [(η⁴-1,5-cyclooctadiene)(1,1′-di-n-butyl-3,3′-ethylene-diimidazolin-2,2′-diylidene)iridium(I) bromide] and 14 [(η⁴-1,5-cyclooctadiene)(1,1′-dimethyl-3,3′-o-xylylene-diimidazolin-2,2′-diylidene)iridium(I) bromide] were characterized by single crystal X-ray analysis. The relative σ-donor/π-acceptor qualities of various NHC ligands were examined and classified in monosubstituted NHC-Rh and NHC-Ir dicarbonyl complexes by means of IR spectroscopy. For the first time, bis(carbene) substituted iridium complexes were used as catalysts in the synthesis of arylboronic acids starting from pinacolborane and arene derivatives.