Preparation and characterization of bis(methylcyclopentadienyl)titanium(IV) dithizonate complexes

Summary Dichlorobis(methylcyclopentadienyl)titanium(IV) reacts with 1,5-diarylthiocarbazones (aryl=phenyl,p-tolyl,o-chlorophenyl orp-chlorophenyl) in 11 and 12 molar ratios in tetrahydrofuran in the presence of triethylamine, to yield [(MeCp)₂Ti(HDz)Cl], [(MeCp)₂Ti(Dz)] and [(MeCp)₂-Ti(HDz)₂] (MeCp=methylcyclopentadienyl; HDz^– and Dz^2– are the mono- and di-anions of a 1,5-diarylthiocarbazone, H₂Dz).S-Methyl-1,5-diphenylthiocarbazone and [(MeCp)₂TiCl₂] react to give [(MeCp)₂Ti(MeDz)Cl] and [(MeCp)₂Ti(MeDz)₂] (MeDz^– represents the mono-anion ofS-methyl-1,5-diphenylthiocarbazone, HMeDz) in an excess of triethylamine. These new derivatives have been characterised on the basis of elemental analyses, magnetic moment, electrical conductance, i.r.,¹H n.m.r. and electronic spectral studies.     

Monocyclopentadienyl titanium(IV) alkyl xanthate complexes

Titanium(IV) alkyl xanthates of the types CpTi(S₂COR)Cl₂, CpTi(S₂COR)₂Cl and CpTi(S₂COR)₃, where R = CH₃, C₂H₅, C₃H₇, C₄H₉ and C₅H₁₁, have been prepared by the reaction of monocyclopentadienyl titanium(IV) trichloride with potassium alkyl xanthates in anhydrous dichloromethane. Conductance and infrared studies suggest that these complexes are non-electrolytes in which all of the xanthate ligands are bidentate. Proton nmr spectra of these complexes indicate that there is rapid rotation of the cyclopentadienyl ring about the metal-ring axis and for the CpTi(S₂COR)₃ complexes non-equivalence of the alkylxanthate ligands was observed.     

Monocyclopentadienyl titanium(IV) dithiocarbamate complexes

Preparation of titanium(IV) complexes of the type CpTi(dtc)Cl₂, CpTi(dtc)₂Cl and CpTi(dtc)₃ has been carried out by reacting CpTiCl₃ and respective sodium dithiocarbamate viz. N-(ethyl, m-tolyl), N-cyclopentyl and N-cycloheptyl dithiocarbamates in the desired metal to ligand ratio in refluxing dichlomethane. Studies of the physical properties reveal monomeric and nonelectrolytic nature of these complexes, where dithiocarbamate behaves as bidentate ligand. Therefore, 5, 6 and 7 coordinate structure can be assigned to CpTi(dtc)Cl₂, CpTi(dtc)₂Cl and CpTi(dtc)₃, respectively.     

Metal complexes of hybrid oxygen-arsenic ligands Part II: Complexes ofo-dialkyl/arylarsinobenzoic acids with cobalt(II) and nickel(II)

Summary Reactions of hybrid oxygen-arsenic ligandso-R₂As-C₆H₄CO₂H (R=Et, C₆H₁₁ andp-tolyl) (2 mols) with M(OAc)₂ · 4H₂O (M=Co or Ni) (1 mol) yield Co(o-R₂As-C₆H₄CO₂)₂ (R=Et orp-tolyl) and Ni(o-R₂AsC₆H₄CO₂)₂ · nH₂O (R=Et, n=0.5; R=C₆H₁₁, n=2) complexes. The electronic spectra and magnetic susceptibilities at different temperatures are compatible with tetrahedral and octahedral stereochemistries for cobalt(II) and nickel(II) complexes respectively. The ligand field parameters (10 Dq and B) have also been calculated and interpreted in terms of metal-ligand bond types.     

Metal complexes of hybrid oxygen — arsenic ligands. Part I. Complexes ofo-dialkyl/arylarsinobenzoic acids with chromium(III)

Summary Reactions of hybrid oxygen-arsenic ligands:o-R₂As-C₆H₄CO₂H (R = Me, Et, C₆H₁₁, Ph andp-tolyl) with CrO₃ and of their sodium salts withtrans-[CrCl₂(H₂O)₄]Cl·2H₂O in a 31 molar ratio yield three types of oxo/hydroxo bridged complexes:a. CrO(o-R₂AsC₆H₄CO₂)nH₂O (R=Me, n=1.5 or 2.5; R=Et, n=1 or 1.5; R=C₆H₁₁, n=1 or 3; R=p-tolyl, n=4),b. Cr(o-Ph₂AsC₆H₄CO₂)₂(OH)2.5 H₂O andc. Cr(o-R₂AsC₆H₄CO₂)(OH)₂nH₂O (R=Ph, n=1; R=p-tolyl, n=0.5). Their i.r. data favour symmetrical chelation of the carboxylate ion, with the metal ion leaving the arsenic(III) uncoordinated. Suitable dimeric, trimeric and tetrameric structures have been assigned for (i) Typea (R=C₆H₁₁, n=1), (ii) Typea (R=p-tolyl, n=4) and (iii) typea. (R= Et, n=1), Typeb. and Typec. (R=p-tolyl, n=0.5) complexes respectively on the basis of solution spectra and experimental molecular weights and _eff values. Calculated ligand field parameters (10 Dq and B) for all the complexes indicate covalent interaction between the metal ion and the ligands.     

Studies on intermolecular interactions of metal chelate complexes. V. copper(ii) dithiophosphate complexes: an example of an inner self-redox reaction

Summary Studies of copper dithiophosphate (dtp) complexes by various physical methods, in the solid and the molten state as well as in solution, are reported. In the solid state all the complexes of dithiophosphate (RO)₂PS ₂ ^– [R = C_nH_2n+1 (n=1–4), Ph, orcyclo-C₆H₁₁] are diamagnetic but in the molten state and in solution they are paramagnetic. Interconversions were found to be reversible, and the effect was ascribed to an inner self-redox reaction. Only the bulkyo-tolyl derivative is paramagnetic in the solid and molten states and in solution. It is proposed that the self-redox reaction involves association between two molecules of Cu^II(dtp)2 during crystallization, followed by formation of [Cu^I(dtp)]₂, and (RO)₂P(S)S-S(S)P(OR)₂, and then [Cu^I(dtp)]₄. The molecular structures of complexes with R = isopropyl ando-tolyl confirm these inferences.Part IV of this series: N. D. Yordanov, V. Iliev, and D. Shopov,Inorg. Chim. Acta, 60, 21 (1982).     

Tridentate chelate π-bonded complexes of rhodium(I), iridium(I), and iridium(III) and chelate σ-bonded complexes of nickel(II), palladium(II), and platinum(II) formed by intramolecular hydrogen abstraction reactions

2,2′-Bis(o-diphenylphosphino)bibenzyl, o-Ph₂PC₆H₄CH₂CH₂C₆H₄PPh₂-o (bdpbz), is dehydrogenated by various rhodium complexes to give the planar rhodium(I) complex

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, from which the ligand, 2,2′-bis(o-diphenylphosphino)-trans-stilbene (bdpps) can be displaced by treatment with sodium cyanide. The stilbene forms stable chelate olefin complexes with planar rhodium(I) and iridium(I) and with octahedral iridium(III). On reaction with halide complexes of nickel(II), palladium(II) or platinum(II), the stilbene ligands

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(R = Ph or o-CH₃C₆H₄) lose a vinyl proton in the form of hydrogen chloride to give chelate, planar σ-vinyls of general formula =CHC₆H₄PR₂-o) (M = Ni, Pd, Pt; X = Cl, Br, I) of high thermal stability; analogous methyl derivatives =CHC₆H₄PR₂-o) are obtained from Pt(CH₃)₂(COD) (COD = 1,5-cyclooctadiene) and the stilbene ligands. The bibenzyl also forms chelate σ-benzyls HCH₂C₆H₄PPh₂-o) (M = Pd, Pt; X = Cl, Br, I). The ¹H NMR spectra of the o-tolyl methyl groups in the compounds =CHC₆H₄PR₂-o) (M = Ni, Pd, Pt; R = o-CH₃C₆H₄) vary with temperature, probably as a consequence of interconversion of enantiomers arising from restricted rotation about the M---P and M---C bonds. Possible mechanisms for the dehydrogenation reactions are briefly discussed.     

Copper(I) and copper(II) complexes of diamino-dithioether ligands

Summary Copper(II) salts were reacted with two diamino-dithioether ligands, i.e. 1,3-di(o-aminophenylthio)propane (abbreviated H₂L¹) and 1,2-di(o-aminophenylthio)xylene (abbreviated H₂L²). Mixtures of copper(I) and copper(II) complexes were obtained with Cl^– and ClO ₄ ^– counterions. The major products were the copper(I) complexes, which were obtained pure after recrystallisation from MeCN-MeOH. The ligands lose two protons from the amine functions to form copper(I) complexes of general formula [CuL]X, where X = ClO ₄ ^– or Cl^–. The complexes were oxidised to [CuL]X₂ with H₂O₂ in DMF. Cu(NO₃)₂ on the other hand gave [CuH₂LNO₃]NO₃.     

Studies on the synthesis,spectra and structure of isomerized products of isopentadiene(dicarbonyl)-[ethoxy(aryl)carbene]iron complexes and the crystal structure of tetracarbonyl[ethoxy-(pentachlorophenyl)carbene]iron

Reaction of π-isopentadienetricarbonyliron (1) with aryl lithium ArLi (Ar?phenyl, p-tolyl, p-methoxyphenyl, p-trifluoromethylphenyl) in ether at low temperature, and subsequent alkylation of the acylmetallate formed with triethyloxonium tetrafluoroborate[(C₂H₅)₃OBF₄] in aqueous solution at 0°C, gave orange-red crystalline complexes (2-5), the isomerized products of isopentadiene (dicarbonyl) [ethoxy(aryl)carbene] iron with composition of C₅H₈ (CO)₂FeC(OC₂H₅)Ar When LiC₆Cl₅ was used as nucleophilic reagent in the reaction, on alkylation of the afforded acylmetallate intermediate under some reaction conditions, complex (CO)₄FeC(OC₂H₅)C₆Cl₅ (6) was obtained. The molecular structure of complexes 2 and 6 were determined by means of single crystal X-ray diffraction measurements. IR, ¹H NMR and mass spectra of these complexes were investigated.     

Ring-opening polymerization of 1-(p-substituted phenyl)-2-vinylcyclopropanes by Ziegler–Natta catalysts

1-(p-Substituted phenyl)-2-vinylcyclopropanes such as 1-phenyl-2-vinylcyclopropane (I_a), 1-(p-chlorophenyl)-2-vinylcyclopropane (I_b), 1-(p-anisyl)-2-vinylcyclopropane (I_c), and 1-(p-tolyl)-2-vinylcyclopropane (I_d) were prepared and polymerized radically, cationically and with Ziegler–Natta catalysts. I_a and I_b polymerized exclusively in 1,5-fashion with radical initiators. However, I_c and I_d polymerized in 1,5-fashion only with Ziegler–Natta catalysts. All polymers were soluble in ordinary organic solvent and solution-cast films were clear and flexible, showing T_g values in the range of 39–71°C. Spectral data indicated that the double bonds of the polymer chains were in trans form in all cases. The difference between the polymerizabilities of different monomers are interpreted in terms of electronic properties of substituents.     

Synthesis,physico-chemical characterization and bioevaluation of Ni(II), Pd(II), and Pt(II) complexes with 1-(o-tolyl)biguanide: Antimicrobial and antitumor studies

New complexes of type [M(tbg)₂]Cl₂ [tbg = 1-(o-tolyl)biguanide; M = Ni(II), Pd(II), and Pt(II)] were synthesized and characterized to develop new biologically active compounds. The features of the complexes were assigned from microanalytical and thermal data. The NMR, FT-IR, and UV-Vis spectra were established by comparison with HtbgCl. All complexes exhibit a square-planar geometry resulting from the chelating behavior of tbg. The HtbgCl and [Ni(tbg)₂]Cl₂ complexes were fully characterized by single-crystal X-ray diffraction. The HtbgCl species crystallize in the monoclinic C2/c spatial group, while the Ni(II) complex adopts an orthorhombic Pna2₁ spatial group. The structure is stabilized by a complex hydrogen bonds network. The in vitro antimicrobial assays revealed improved antimicrobial activity for complexes in comparison with the ligand against both planktonic and biofilm embedded microbial cells. The most efficient compound, showing the largest spectrum of antimicrobial activity, including Gram-positive and Gram-negative bacteria, as well as fungal strains, in both planktonic and biofilm growth states was the Pd(II) complex, followed by the Pt(II) complex. The Pt(II) compound exhibited the most significant antiproliferative activity on the human cervical cancer SiHa cell line, inducing a cell cycle arrest in the G2/M phase.     

Thermal Decomposition of Trialkyl/Arylphosphine Gold(I) Cyanide Complexes

Combined TG/DTA techniques have been used to study the thermal decomposition of R₃PAuCN (where Ris ethyl, cyclohexyl, o-tolyl, m-tolyl, p-tolyl, allyl, cyanoethyl,1-naphthyl and phenyl) complexes. It was observed that all of these complexes underwant decomposition cum redox reactions in the range of 200–600oC with evolution of both transligands, which are phosphine and cyanide, leaving metallic gold as a residue. The thermal decomposition of o-Tol₃PAuCN has revealed that this is a stepwise process. In the first step decomposition takes place with evolution of phosphine and generation of AuCN, which in second step undergoes a redox reaction to produce metallic gold. The DTA curves have also confirmed these results. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and spectral studies ofo-hydroxyacetophenone (N-benzoyl)glycyl hydrazone and some of its lanthanide(III) complexes

Summary o-Hydroxyacetophenone (N-benzoyl)glycyl hydrazone (o-HABzGH) has been characterized by i.r.,¹H n.m.r.,¹³C n.m.r. and mass spectral studies, and its complexes of the types [Ln(o-HABzGH)Cl₂(H₂O)₂]Cl and [Ln(o-HABzGH–2H)OH(H₂O)₃], where Ln=La, Pr, Nd, Sm and Eu, have been synthesized. The structures of the complexes have been studied by conductance, magnetic, electronic, i.r.,¹H n.m.r. and¹³C n.m.r. spectral techniques. The hypersensitive bands of the electronic spectra suggest coordination numbers six and seven around Nd^III in its adduct and neutral complexes respectively. I.r. and n.m.r. spectral data suggest a neutral bidentate behaviour for the ligand in the adducts and a dinegative tridentate nature in the neutral complexes.     

Preparation,characterization and Mössbauer spectra of the iron(III) complexes of some dihydroxamic acids and amino monohydroxamic acids

Summary Fe^III complexes have been prepared from the dihydroxamic acids (CH₂)_n[CON(R)OH]₂ (n=2, 3, 4, 6, 8; R=H, Ph,o-tolyl,p-tolyl) (H₂L) and the amino monohydroxamic acids H₂NCH(R)CONHOH (R=H, Me) (HL) and XC₆H₄CONHOH (X=o-NH₂,p-NH₂) (HL). Based on elemental analyses, molecular weight data, and electronic and i.r. spectra, the complexes have been formulated as Fe₂(LH)₂L₂, Fe₂L₂O and Fe₂L₃ for the dihydroxamic acids, and Fe(OH)₄L₂(H₂O)₂ and FeL₃ for the amino monohydroxamic acids. The⁵⁷Fe Mossbauer spectra are discussed.The author is née Bose     

Pentafulvenkomplexe des Titans — Synthese,Struktur und Fluktuierendes Verhalten von Cp′Ti{η6‐C5H4=C(p‐Tol)2}Cl (Cp′ = Cp*, Cp)

Complexes of Titanium — Synthesis, Structure, and Fluxional Behaviour of CpTi{η⁶‐C₅H₄=C(p‐Tol)₂}Cl (Cp′ = Cp*, Cp) The reaction of Cp′TiCl₃ (C′ = Cp* or Cp) with magnesium and 6, 6‐di‐para‐tolylpentafulvene generates good yields of pentafulvene complexes Cp*Ti{η⁶‐C₅H₄=C(p‐Tol)₂}Cl ( 4 ) and CpTi{η⁶‐C₅H₄=C(p‐Tol)₂}Cl ( 5 ), respectively. The crystal and molecular structure of 4 have been determined from X‐ray data and exhibits compared to known η⁶‐pentafulvene complexes an unusual large Ti—C(p‐Tol)₂ (Fv)‐distance (2.535(5)Å) evoked by the bulky substituents at the exocyclic carbon. Dynamic ¹H‐NMR and spin saturation transfer experiments point out a rotation of the fulvene ligand around the Ti—Ct2 axis (Ct2 = centroid of the fulvene ring carbon atoms) with an activation barrier ΔG^≠_C = 60.6 ± 0.5 kJ mol⁻¹ (T_C = 314 ± 2 K). For 5 this barrier is significantly larger. Analogous dynamic behaviour is well known for diene complexes, but to our knowledge, it is here first‐time described for a pentafulvene complex.     

Reactions of Ru(Cp) complexes with P(o-tolyl)3

Reaction of [Ru(Cp^∗)(CH₃CN)₃](PF₆) with P(o-tolyl)₃ affords [Ru(Cp^∗){(η⁶-o-tolyl)P(o-tolyl)₂}](PF₆) (4) in which the P-atom is not coordinated to the metal. The solid-state structure of 4 has been determined. A related reaction with P(p-tolyl)₃ reveals a small quantity [Ru(Cp^∗){(η⁶-p-tolyl)P(o-tolyl)₂}](PF₆), in solution, but mostly the expected bis-phosphine complex. Reaction of the Ru(IV) dication, [Ru(Cp^∗)(η³-PhCHCHCH₂)(DMF)₂](PF₆)₂, with P(o-tolyl)₃ gives a mixture of the phosphonium salt, C₆H₅CHCHCH₂P(o-tolyl)₃ (9) and the dication [Ru(Cp^∗) (η⁶-C₆H₅CHCHCH₂P(o-tolyl)₃)](PF₆)₂ (10). Salt 9 forms via attack of the P-atom on the allyl ligand. The latter product results from complexation of 9 via the phenyl group of the former allyl ligand. It would seem that the sterically demanding P(o-tolyl)₃ ligand is not readily compatible with the Ru(Cp^∗) fragment, in either the +2 or +4 oxidation state. Detailed NMR studies are reported.     

Complex compounds of 1,5-disubstituted 2,4-dithiobiurets with copper(II) chloride

1,5-diphenyl, 1,5-di-p-tolyl, 1-phenyl 5-0-tolyl, 1-phenyl 5-p-tolyl and 1-methyl 5-p-tolyl 2,4-dithiobiurets react with anhydrous copper(II) chloride in alcohol to form golden yellow complexes of general formula [CuL₂]· Cl₂, where L is a molecule of the ligand. The structures of these complexes have been studied by infrared spectroscopy, conductance and magnetic susceptibility measurements. The unusual magnetic moment (1.11–1.34 B.M.) values of these complexes are indicative of the metal–metal bonding. The structure of these complexes are proposed to have square planer configurations.     

The reactions of diborane with aryl-organotin compounds

A number of tetraaryltin compounds, Ar₄Sn (where Ar = phenyl, o- and p-tolyl, and p-chlorophenyl) and triphenyltin compounds, Ph₃SnX (where X = Cl, H, OH, OCOCH₃, and OCOCF₃) have been treated with diborane in tetrahydrofuran. Transmetallation occurs in which one or more aryl groups are transferred to boron. The organoboron intermediates give phenols upon oxidation and boronic and borinic acids upon hydrolysis. Pyridine complexes of organoboranes have also been isolated.     

Carbon–13 NMR studies of tautomerism in some 2-substituted imidazoles and benzimidazoles

The ¹³C NMR spectra of several 2-substituted imidazoles and benzimidazoles have been measured. The substituent was CH₃, COOH and CONHR, where R = H, n-Bu, p-tolyl or m-chlorophenyl. Carbons 4 and 5 in the imidazoles and the carbon pairs 8/9, 4/7 and 5/6 become equivalent by proton transfer from N-1 to N-3, possibly through intermolecular association. The rate of this proton exchange increases with concentration and temperature. It decreases with extension of the 2-substituent (rate CH₃?CONH-phenyl > CONH-p-tolyl ? CONH-m-chlorophenyl ? CONH-n-butyl) due to steric hindrance at the site of the (benz)imidazole nitrogen.     

Copper(II) complexes of entwined 2,9-di(o-substituted phenyl)-1,10-phenanthroline type ligands and intramolecular quenching in copper(I) complexes

Cu¹¹ complexes of 1,10-phenanthroline, disubstituted at the 2 and 9 positions or monosubstituted at the 2 position by phenyl moieties possessingortho substituents, were prepared and investigated by spectroscopic and electrochemical methods. The electronic spectral d-d band position varies from 14 500 to 13 200 cm⁻¹. E.s.r. g_‖ values are between 2.256 to 2.283 and A_‖ between 164 to 117×10⁻⁴ cm⁻¹. Thebis[2,9-di(o-substituted phenyl)-1,10-phenanthroline]Cu¹¹ complexes undergo reversible one-electron electrochemical reduction (Cu¹¹/Cu¹) in the +0.536 to +0.825 V potential range versus s.c.e., whereas thebis[2-mono(o-substituted phenyl)-1,10-phenanthroline]Cu¹¹ complexes undergo reduction in the +0.360 to +0.405 V range; the redox couple is found to be quasireversible. Emission studies on copper(I) complexes show that onlybis[2,9-di(o-tolyl)-1,10-phen]Copper(I) complex exhibits emission properties. Emission behaviour of other structurally similar compounds is explored. TMC 2555