Improved syntheses of Ru(CO)2 (O3SCF3)2 (bidentate) complexes and their conversion into new [Ru(CO)2 (bidentate)2]2+ complexes

Reaction of the complexes Ru(CO)₂Cl₂L [L = 2,2′-bipyridyl (bpy) or 1,10-phenanthroline (phen)] with trifluoromethanesulphonic acid under carefully controlled conditions yields Ru[cis-(CO)₂] [cis-(O₃SCF₃)₂] (bidentate complexes. From reactions of the trifluoromethanesulphonates with the appropriate bidentate ligands, the new complexes [cis-Ru(CO)₂-L(L′)]²⁺ (L as above; L′ = 4,4′-dimethyl-2,2′-bipyridyl or 4,4′-diisopropyl-2,2′-bipyridyl) as well as the known [_cis-Ru(CO)₂L₂]²⁺ and [cis-Ru(CO)₂bpy(phen)]²⁺ have been prepared.     

Thermal and Some other Properties of 2,4′-Bipyridyl Complexes with Various Salts of Lead(II)

New complexes of lead(II) with 2,4′-bipyridyl (L), with the general formulae PbL₂X₂ (where X ^?1=Cl, Br, I, NCS) and PbL₃X₂ (where (X]^?1=NO₃, ClO₄), have been prepared. Analysis of the IR spectra indicates that the 2,4′-bipyridyl is bonded to the Pb(II) ion through the least hindering N(4′). The thermal decompositions of the complexes were studied under non-isothermal conditions in air. The intermediates of decomposition at different temperatures were characterized by thermal analysis (TG and DTG), chemical analysis and X-ray diffraction. Upon heating, the complexes undergo full or partial deamination. The complexes PbL₂Cl₂ and PbL₂Br₂ decompose to volatile lead(II) halide. PbO is the final product of decomposition for the other complexes.     

Structural effects on the antitumour activity of a series of di(4-substituted phenyl)tin dichloride complexes with nitrogen-donor ligands

Investigation of the antitumour activity of a series of diorganotin dichloride complexes (4-ZC₆H₄)₂SnCl₂·L₂, where Z = OMe, Me, F, Cl, and CF₃ and L₂ = 2,2′-bipyridyl (bipy), 1,10-phenanthroline (phen) and 2-aminomethylpyridine (amp) is reported. A number of these complexex are shown to exhibit reproducible activity in vivo towards P388 lymphocytic leukaemia in mice. ¹H NMR data are reported for an extended series of (4-ZC₆H₄)₄Sn and the parent dichlorides (4-ZC₆H₄)₂SnCl₂ of the above-mentioned complexes. A correlation is reported between Hammett substituent constants and ¹H chemical shift data. Attempts are made to relate the antitumour activity of the complexes to various structural factors. The dependence of antitumour activity on the electronic effect of group Z and the nature of the ligand L₂ is demonstrated.     

Übergangsmetallcarbin-komplexe: LXXXV. Strukturuntersuchungen der reaktionsprodukte von trans-Br(CO)2L2LCNEt2 (L2 = 2,2′-bipyridyl, 1,10-phenanthrolin) mit den organylanionen [(CO)5MEPh2]− (M = Cr,Mo, W; E = P,As, Sb)

The reaction of trans-Br(CO)₂L₂WCNEt₂ (L₂ = 2,2′-bipyridyl (2,2′-bipy), 1,10-phenanthroline (ophen)) with organyl anions of Main Group V elements coordinated to a pentacarbonylmetal fragment of the general formula [(CO)₅MEPh₂]⁻ (M = Cr, Mo, W; E = P, As, Sb) leads, by substitution of the bromine ligand, to new neutral diethylaminocarbyne complexes of the type (CO)₅MEPh₂(CO)₂L₂-WCNEt₂ (M = Cr, Mo, W; E = P, As, Sb; L₂ = 2,2′-bipy, ophen) which contain a heavier element of Main Group V in a bridging position between two transition metals. Spectroscopic investigations at low temperatures show that the bridged complexes exist as a mixture of cis and trans isomers, with the thermodynamic equilibrium favouring the cis complexes. Temperature dependent NMR spectra indicate a dynamic process in which the chelating ligand L₂ (L₂ = 2,2′-bipy, ophen) switches between two cis and two cis / trans positions, relative to the carbyne ligand, and causes a rapid interconversion of the two stereoisomers at room temperature.     

Synthesis of organopalladium(IV) complexes by halogen exchange,and the structure of the azidopalladium(II) complex formed on reductive elimination of ethane from Pd(N)3Me2(CH2Ph)(bpy)

A new route to organopalladium(IV) complexes is described, involving replacement of bromine in the 2,2′-bipyridyl complex PdBrMe₂(CH₂Ph)(by), by other halogen or pseudohalogen groups. ¹H NMR studies of the decomposition of PDXMe₂(CH₂Ph)(bpy) in warm (CD₃)₂CO indicate that a selectivity in reductive elimination of alkanes occurs. to give ethane (X = Br, N₃, NCS), or a mixture of ethane and ethylbenzene in ca. 9/1 ratio (X = F. Cl, I). The reductive elimination product azido(2,2′-bipyridyl)benzylpalladium(II) has been characterized by X-ray crystallography.     

SYNTHESIS AND CHARACTERIZATION OF DINUCLEAR,BRIDGED COMPLEXES OF THE TYPE LxM(NCSe)2M′(SCN)2L′2

Abstract

L _x M(NCSe)₂ M′(SCN)₂(PPh₃)₂ [M=Co(II), Ni(II); M′=Hg(II), Cd(II), Zn(II); L=pyridine (py), 2,2′-bipyridyl (bipy); x=4, 2] have been synthesized. Elemental analysis, magnetic moment, electronic and infrared spectral and thermogravimetric studies indicate that these complexes are dinuclear. The total softness of M and M′ in the complexed state have also been calculated to derive certain conclusions.     

Three-coordinate mercury in (2,2′-bipyridyl)methylmercury(II) nitrate and related complexes

Methylmercury(II) forms complexes [MeHgL]⁺ [NO₃]^? (L = bidentate ligand) having three-coordinate mercury; an X-ray crystal structure analysis shows that the complex with 2,2′-bipyridyl has a planar CHgN₂ group with unsymmetrically chelated 2,2′-bipyridyl.     

Crystal solvates of zinc(II) bis(dipyrrinates) with triethylamine: composition,stability and spectral-luminescent properties

Crystal solvates of 2,2′-, 2,3′- and 3,3′-bis(dipyrrinato)zinc^(II) with triethylamine (TEA) were obtained by slow crystallization. Composition, structural organization, stability, and spectral-luminescent properties of the crystal solvates were studied by FTIR, Powder X-ray Diffraction, thermal, mass spectral, absorption and fluorescence analyses. The thermal dissociation processes of crystal solvates in an argon atmosphere have been investigated. It is shown that zinc^(II) helicates with decamethylsubstituted 2,2′-, 2,3′-, and 3,3′-bis(dipyrrin)s with TEA form stable supramolecular complexes of the composition [Zn₂L₂(TEA)₄] and [Zn₂L₂TEA]. Spectroscopic studies showed that the quantum yield (φ) of [Zn₂L₂(TEA)_n] crystal solvates in cyclohexane is noticeably (3–4.5 times) lower than φ of [Zn₂L₂] complexes. Quantum chemical study indicated the most likely mechanism for the coordination of solvent molecules on the coordinating centers of [Zn₂L₂]. Thermal and energy stability of [Zn₂L₂(TEA)_n] solvates reduced when replacing the 2,2′- on 2,3′-, and 3,3′-isomer. The obtained results are of interest for the development of [Zn₂L₂] fluorescent sensors of the electron donor molecules.     

A 199Hg NMR spectroscopic study of two and three-coordinate methylmercury(II) complexes, [MeHgL]NO3

¹⁹⁹Hg NMR spectra are reported for the complexes [MeHgL]NO₃ containing either two- (e.g. L = pyridine) or three-coordinate mercury (e.g. L = 2,2′-bipyridyl). For unidentate and bidentate ligands of similar basicity chelation with bidentate ligands to give three-coordinate mercury results in upfield shifts of ¹⁹⁹Hg resonances from that of the linear complexes. For complexes of unidentate ligands shifts correlate with changes in base strength of the ligands, and methyl substitution in the 2 position of pyridine appears to result in an upfield shift of ca. 30 ppm. Effects of substitution in the 2 position are very strong in complexes of unidentate 2-benzylpyridine and 3,3′-dimethyl-2,2′-bipyridyl. Comparison of the ¹⁹⁹Hg shifts with J(¹H-¹⁹⁹Hg) shows the coupling constant to be insensitive to substitution in the 2 position in linear complexes and is a function only of the ligand base strength.     

Electro-oxidation and electro-reduction of some iron (II), cobalt(II) and nickel(II) polypyridyl complexes in acetonitrile

Cyclic voltammetry and controlled potential coulometry studies of 2,2′-bipyridyl, 4,4′-dimethyl-2,2′-bipyridyl and 2,2′, 2″-terpyridyl complexes of Fe(II), Co(II) and Ni(II) in acetonitrile are described. E_1/2 values for M(III)/M(II) and M(II)/M)I) couples are compared and crystal field effects discussed. A series of M(I) and M(III) polypyridyl complexes have been prepared by controlled potential electrolysis; these include a number of 3+ and 1+ oxidation state complexes of nickel which have not previously been isolated — [Ni(bipy)₃]-(ClO₄)₃, [Ni(dimbipy)₃](ClO₄)₃, [Ni(terpy)₂](ClO₄)₃ and [Ni(bipy)₂]ClO₄.     

Four novel lanthanide complexes with 4‐ethylbenzoic acid and 5,5′‐dimethy‐2,2′‐bipyridine: Structures,luminescent, thermal properties and bacteriostatic activities

Four new lanthanide complexes [Ln(4‐EBA)₃(5,5′‐DM‐2,2′‐bipy)]₂·2C₂H₅OH (Ln = Ho ( 1 ), Tb ( 2 ), Er ( 3 )); [Ln(4‐EBA)₃(4‐EBAH)(5,5′‐DM‐2,2′‐bipy)]₂ (Ln = Eu( 4 ); 4‐EBA =4‐ethylbenzoate; 5,5′‐DM‐2,2′‐bipy =5,5′‐dimethy‐2,2′‐bipyridine; 4‐EBAH = 4‐ethylbenzoic acid) have been synthesized and characterized by elemental analysis and IR spectra. The single crystal results reveal that complexes 1 – 3 are isostructural. It is worth noting that the mole ratios of the carboxylate ligands and neutral ligands is 4:1 in complex 4 , which is different from the former and has been rarely reported. Nevertheless, all complexes are connected to form 1D chain by π ···π wake staking interactions. Additionally, the complexes 2 (Tb(III)) and 4 (Eu(III)) exhibit characteristic luminescent properties, indicating that ligands can be used as sensitizing chromophore in these systems. The thermal decomposition mechanism of the complexes has been investigated by TG/DSC–FTIR technology. Stacked plots of the FTIR spectra of the evolved gases show complexes broken down into H₂O, CO₂, and other gaseous molecules as well as the gaseous organic fragments. The studies on bacteriostatic activities of complexes show that four complexes have good bacteriostatic activities against Candida albicans but no bacteriostatic activity on Escherichia coli , and Staphylococcus aureus . Additionally, the complexes 1 to 3 have better bacteriostatic activities on Candida albicans than complex 4 .     

Koordinationsverbindungen von Bortrialkylen. II. Zur Komplexbildung zwischen Bortriallylen und tertiären Aminen

Coordination Compounds of Boron Trialkyls. II. On the Complex Formation between Boron Triallyls and Tertiary Amines It is reported on complexes of triallyl, trimethallyl, and tricrotyl boron with N,N-,N′,N′-tetraethylethylene diamine, pyridine, and 2,2′-bipyridyl. Whilst only 1:1 complexes exist with pyridine, 1:1 and 2:1 complexes are formed with tetraethylethylene diamine. Bipyridyl reacts with triallyl boron with formation of the boronium salt [(all)₂B(dipy)][B(all)₄].     

The influence of the nature of the ligand,L, on the electrochemical behaviour of dinitrosyl molybdenum complexes,Mo(NO)2L2Cl2, in aprotic media

Electrochemical investigations of the reduction of dicationic, monocationic and neutral dinitrosyl molybdenum complexes in nitromethane and acetonitrile are reported. All the compounds with the general formulae: [Mo(NO)₂L₂L′₂]²⁺, [Mo(NO)₂L₂L′Cl]⁺ and Mo(NO)₂L₂Cl₂ (L = CH₃CN, CH₂CHCN, C₆H₅CN, C₅H₅N, P(C₆H₅)₃, L₂ = 2,2′-bipyridine, L′ = CH₃CN and L′₂ = 2,2′-bipyridine) are reducible by one electron to yield 19-electron complexes. The dicationic complexes undergo a reversible one-electron transfer. For the mono- and dichlorocomplexes, the one-electron transfer induces the facile exchange of the chloroligand in the 19-electron complexes except for L₂ = 2,2′-bipyridine. However, the exchange of the chloroligand is followed by the fast anation by Cl^? of the remaining 18-electron chlorocomplexes to afford [Mo(NO)₂Cl₃L]^? and [Mo(NO)₂Cl₄]^2? which are reducible at higher negative potentials than dichloro- and monochlorocomplexes. The multiple electrochemical step system is not catalytic, but of the electroactivation type.     

Structure and stability of molecular and ionic complexes of AlCl3 with pyrazine and 4,4′-bipyridyl

Structural and thermodynamic characteristics of molecular and ionic complexes of aluminum trichloride with pyrazine (pyz) and 4,4′-bipyridyl (bipy) are calculated at the RI-BP86/def2-SVP level. It is found that for molecular 2AlCl₃·3L and 4AlCl₃·3L complexes an energy difference between isomers does not exceed 4 kJ/mol, and the rotation barrier of the AlCl₃ moiety relative to the N-Al-N bond does not exceed 24 kJ/mol. A comparison of the stability of molecular and ionic complexes of aluminum in the gas phase shows that the maximum energy difference is ～60 kJ/mol. For L = pyz the molecular complex is more stable whereas for L = bipy it is the ionic one.     

Synthesis, Characterization, Spectroscopic and Electrochemical Properties of New Mono- and Binuclear Copper（Ⅰ） Complexes with Substituted 2,2′-Bipyridine

The mono- and binuclear Cu(Ⅰ) complexes with substituted 2,2′-bipyridine and iodide ligands, [CuL2]BF4(L=4-methoxycarbonyl-6-(4-methylphenyl)-2,2′-bipyridine (a), 6-(4-hydroxymethylphenyl)-2,2′-bipyridine (b) and 6-(4-methoxylphenyl)-2,2′-bipyridine (c)) and [Cu2(μ-I)2L2] were prepared, and the crystal structures of the complexes were obtained from signal-crystal X-ray diffractional analysis. The spectroscopic properties of the complexes in dichloromethane are dominated by low energy MLCT bands from 360 to 650 nrn. The electrochemical studies of mononuclear complexes reveal that the complexes have stable copper(Ⅰ) state.     

Molecular complexes of aryltellurium(IV) chlorides

The synthesis and spectroscopic study of molecular complexes of type [RTeCl₃ · L] and [RTeCl₃ · 2L], where R = phenyl, 4-phenoxyphenyl and L = pyridine, pyridine-N-oxide, tri-n-octylphosphine oxide, 1,10-phenanthroline and 2,2′-bipyridyl are reported. These compounds were characterised by their IR spectra, elemental analysis and conductivity data. The conductivities in acetonitrile shows the non-electrolytic behaviour of these hygroscopic compounds which are monomeric in boiling benzene.     

The effect of 2,2′-bipyridyl on the stability of Cu(II) complexes with carboxylic acids

The stability constants β₂, and β₂ of simple Cu(II) complexes with methoxyacetic, phenylacetic, and cyclohexylacetic acid were determined spectrophotometrically and compared with the stability of composite complexes containing 2,2′-bipyridyl as the first ligand and the above mentioned acid as the second ligand. In each case the stability of the composite complex Cu(bip)L⁺ was found to exceed that of the simple complex CuL⁺ and the differences in the values of log β are comprised within 0.15–0.17.     

New complexes of Mn(II), Co(II), Ni(II) AND Cu(II) with 2,2’- OR 2,4’-bipyridine and formates (Synthesis, thermal and other properties)

New mixed-ligand complexes with empirical formulae: Mn(2-bpy)_1.5L₂·2H₂O, M(2-bpy)₂L₂·3H₂O (M(II)=Co, Cu), Ni(2-bpy)₃L₂·4H₂O and M(2,4’-bpy)₂L₂·2H₂O (where 2-bpy=2,2’-bipyridine, 2,4’-bpy=2,4’-bipyridine; L=HCOO^– ) have been obtained in pure solid-state. The complexes were characterized by chemical and elemental analysis, IR and VIS spectroscopy, conductivity (in methanol and dimethylsulfoxide). The way of metal-ligand coordination discussed. The formate and 2,4’-bpy act as monodentate ligands and 2-bpy as chelate ligand. The new complexes with ligand isomerism were identified. During heating the complexes lose water molecules in one or two steps. Thermal decomposition after dehydration is multistage and yields corresponding metal oxides as final products. A coupled TG-MS system was used to analysis principal volatile thermal decomposition (or fragmentation) products of Ni(2,4’-bpy)₂(HCOO)₂·2H₂O under dynamic air or argon atmosphere.     

3,3′-Dicarbomethoxy-2,2′-bipyridyl complexes of palladium(II), platinum(II) and rhodium(III)

3,3′-Dicarbomethoxy-2,2′-bipyridyl(DCMB)reacts with K₂MCl₄(M = Pd,Pt) to give M(DCMB)Cl₂ and with RhCl₃ to give the cis-[Rh(DCMB)₂Cl₂]⁺ ion. Attempts to prepare the tris (DCMB) complex with Rh(III) and analogous Co(III) complexes were unsuccessful.     

Synthesis and thermal behaviour of 4,4′-bipyridyl and 2,4′bipyridyl complexes of Co(II), Ni(II) and Cu(II) thiocyanates

The synthesis and characterization of CoL₂(NCS)₂·2H₂O, NiL₂(NCS)₂·2H₂O, CuL(NCS)₂· 3H₂O (L=4,4′-bipyridyl, 4-bipy) CoX₃(NCS)₂·H₂O, NiX₃(NCS)₂ and CuX₂(NCS)₂ (X=2,4′- bipyridyl, 2,4′-bipy) are reported. The IR spectra and other physical properties of these compounds are discussed. The thermal properties of the complexes in the solid state were studied under non-isothermal conditions in air atmosphere. The intermediates of dehydration and decomposition at different temperatures were characterized by X-ray diffraction.