Zur reaktion von metall-koordiniertem kohlenmonoxid mit yliden: XI. Einige neuartige η1-vinyl-komplexe des eisens durch deprotonierung kationischer carbenkomplexe mit trimethyl(methylen)phosphoran

Novel η¹-vinyl complexes of the type Cp(CO)(L)FeC(OMe)C(R)R′ (R = R′ = H, Me; R = H, R′ = Me; L = Me₃P, Ph₃P) are obtainied via methylation of the acyl complexes Cp(CO)(L)FeC(O)R (R = Me, Et, i-Pr) with MeOSO₂F and subsequent deprotonation of the resulting carbene complexes [Cp(CO)(L)FeC(OMe)R]SO₃F with the phosphorus ylide Me₃PCH₂. The same procedure can be applied for the synthesis of the pentamethylcyclopentadienyl derivative C₅Me₅(CO)(Me₃P)FeC(OMe)CH₂, while treatment of the hydroxy or siloxy carbene complexes [Cp(CO)(L)FeC(OR)Me]X (R = H, Me₃Si; X = SO₃CF₃) with Me₃CH₂ results in the transfer of the oxygen bound electrophile to the ylidic carbon. Some remarkable spectroscopic properties of the new complexes are reported.     

Chemistry of mixed transition-metal complexes : VII. Iron- and nickel-substituted cyclobutadiene complexes of cobalt

The preparation of π-cyclopentadienyl(substituted cyclobutadiene)cobalt complexes by the reaction of π-C₅H₅Co(PPh₃)(RCCR′) (R, R′ = Ph, CO₂CH₃ with ethynyl complexes R″CCM (R″ = Ph for M = π-C₅H₅Fe(CO)(L);R″ = Ph, Co₂CH₃ for M = π-C₅H₅Ni(PPh₃)) is described.     

Cyclic voltammetry of iron dimine complexes in acetonitrile

The electrochemical behavior of iron diimine complexes, (H₃C?N=C(R)?C(R′)=N?CH₃)₃Fe(II) (R, R′=H,H;H, CH₃; CH₃, CH₃), and (C₅H₄N?C(R₁)=N(R₂))₃Fe(II) (R₁, R₂=H, CH₃; CH₃, CH₃) on a platinum working electrode in acetonitrile is described, and compared to that of the parent aromatic complex, tris-(2,2′-bipyridine)Fe(II). One-electron reversible oxidations were found for all the compounds studied. The electrochemical reductions show 2–3 reduction waves in the potential range studied. Only for the complexes of mixed diimine ligands or 2,2′-bipyridine, a pre-adsorption wave is also observed. It is possible to stabilize low valence states with all ligands studied. A formal iron(I) state is described for the first time for all aliphatic diimine complexes, thus showing that the acceptor properties of the diimine complexes do not depend on the presence of the aromatic rings, but on the iron-diimine chromophore.     

Chiral poly(pyrazolyl)borate ligands and complexes: III. Chiral poly(pyrazolyl)borate isonitrile complexes of molybdenum and tungsten

The syntheses of enantiomeric and diastereoisomeric Bpz₄M★(CO)(NO)(CNR) complexes (M = Mo, W; R = CH₂CH₃, CH₂Ph, C★H(CH₃)(C₆H₅)) are reported. When R = CH₂CH₃ or CH₂C₆H₅ the presence of the diastereotopic methylene hydrogens does not allow the detection of the neighbouring chiral center, because they are magnetically equivalent. The diastereoisomeric complexes show different ¹H NMR signals, but cannot be resolved by liquid chromatography or by crystallization.     

Synthesis of new mixed ligand complexes of copper(II) dithiocarbamates

New mixed ligand complexes of copper(II) dithiocarbamates of the general formula, [CuCl(R₂dtc)L] or [CuCi(R′ dtc)L] (RCH₃ or C₂H₅, R′ = (CH₂)₅, dtc =-NCSS^? and L = Pyridine, 3-picoline or 4-picoline), have been prepared by the reaction of bis(dithiocarbamato)di-μ-chloro-dicopper(II) complexes with pyridine or picolines. The complexes are found to be non-electrolytes in nitrobenzene. Magnetic susceptibilities, i.r. and electronic spectra of the complexes are reported. A psuedo-tetrahedral structure is suggested for these complexes.     

Synthesis reactivity and electrochemical properties of substituted cyclopentadienyl cobalt (III) complexes

Cyclopentadienyl cobalt complexes (η⁵‐C₅H₄R) CoLI₂ [L = CO,R=‐COOCH₂CH=CH₂ (3); L=PPh₃, R=‐COOCH₂‐CH=CH₂ (6); L=P(p‐C₆H₄O₃)₃, R = ‐COOC(CH₃) = CH₂ (7), ‐COOCH₂C₆H₅ (8), ‐COOCH₂CH = CH₂ (9)] were prepared and characterized by elemental analyses, ¹H NMR, ER and UV‐vis spectra. The reaction of complexes (η⁵‐C₅H₄R)CoLI₂ [L= CO, R= ‐COOC(CH₃) = CH₂ (1), ‐COOCH₂C₆H₅(2); L=PPh₃, R=‐COOC (CH₃) = CH₂ (4), ‐COOCH₂C₆H₅ (5)] with Na‐Hg resulted in the formation of their corresponding substituted cobaltocene (η⁵‐C₅H₄R)₂ Co[R=‐COOC(CH₃) = CH₂ (10), ‐COOCH₂C₆H₅ (11)]. The electrochemical properties of these complexes 1–11 were studied by cyclic voltammetry. It was found that as the ligand (L) of the cobalt (III) complexes changing from CO to PPh₃ and P(p‐tolyl)₃, their oxidation potentials increased gradually. The cyclic voltammetry of α,α′‐substituted cobaltocene showed reversible oxidation of one electron process.     

Dirhodium(II) dicarboxylato complexes containing carbonyl and C-bonded methoxycarbonyl ligands

Oxidation of rhodium(I) carbonyl chloride, [Rh(CO)₂Cl]₂, with copper(II) acetate or isobutyrate in methanol solutions yields binuclear double carboxylato bridged rhodium(II) complexes with RhRh bonds, [Rh(μ-OOCRκO)(COOMeκC)(CO)(MeOH)]₂, where R=CH₃ or i-C₃H₇. According to X-ray data, surrounding of each rhodium atom in these complexes is close to octahedral and consists of another rhodium atom, two oxygens of carboxylato ligands, terminal carbonyl group, C-bonded methoxycarbonyl ligand, and axial CH₃OH. Methoxycarbonyl ligand is shown to originate from CO group of the parent [Rh(CO)₂Cl]₂ and OCH₃ group of solvent. N- and P-donor ligands L (p-CH₃C₆H₄NH₂, P(OPh)₃, PPh₃, PCy₃) readily replace the axial MeOH yielding [Rh(μ-OOCRκO)(COOMeκC)(CO)(L)]₂. The X-ray data for the complex with R=i-C₃H₇, L=PPh₃ showed the same molecular outline as with L=MeOH. Electronic effects of axial ligands L on the spectral parameters of terminal carbonyl group are essentially the same as in the known series of rhodium(I) complexes (an increase of δ¹³C and a decrease of ν(CO) with strengthening of σ-donor and weakening of π-acceptor ability of L).     

Reactions of alkylcobalt complexes containing a tetradentate nitrogen-donating ligand

The reactions of RCo(BDM1,3pn)(H₂O) with light, heat, acids, electrophiles and nucleophiles were studied. (HBDM1,3pn is a mononegative, tetradentate dioxime-diimine ligand formed by condensing 2,3-butanedionemonoxime with 1,3-propanediamine in a 2/1 molar ratio; R = CH₃, C₂H₅, n-C₃H₇, n-C₄H₉, and C₆H₃CH_2-) Pyrolysis and photolysis of the alkyl complexes result in a cobalt(II) complex (anaerobic conditions) along with alkenes and alkanes. The major organic products from solid state pyrolysis at 200°C or photolysis in water are CH₄ (R = CH₃), C₂H₄ (R = C₂H₅), C₃H₆ (R = n-C₃H₇), C₄H₈ (R = n-C₄H₉) and (C₆H₅CH₂)₂ (R = C₆H₅CH₂). No alkyl—cobalt bond cleavage occurs with acids or bases in most cases. Two exceptions are the reactions with 3 M HNO₃ at 25°C and with 1 M NaOH at 52°C. Electrophiles like I₂ cleave the alkyl—cobalt bond forming RI and Co^III (BDM1,3pn)I₂. Nucleophilic reagents (N^-) displace the H₂O trans to the alkyl group to form RCo(BDM1,3pn)(N), but do not dealkylate the alkyl complex under the reaction conditions studied.     

Organometallic and organobimetallic complexes of platinum(II) containing 2,2′-bipyrimidyl: syntheses and spectroscopic characteristics

Preparations are described of several monometallic complexes (bipym)PtR₂ [bipym = 2,2′-bipyrimidyl; R = Me, CF₃, Ph, 1-adamantylmethyl (adme); R₂ = (CH₂)₄] and bimetallic analogues R₂Pt(μ-bipym)PtR′₂ [R = R′ = CH₃, C₆H₅, adme; R = CH₃, R′ = Ph, adme, CF₃]. IR, ¹H NMR and UV/visible spectroscopic characteristics of the two modes of bipyrimidyl coordination are discussed.     

Alkyl- und Arylkomplexe des Iridiums und Rhodiums. XIX. Reaktion von Carbonsäuren mit ausgewählten Organoverbindungen von Ir(I) und Rh(I): Bildung von Arylhydrido-, Carboxylatohydrido- und Carboxylato-Derivaten

Alkyl and Aryl Complexes of Iridium and Rhodium. XIX. Reaction of Carboxylic Acids with Selected Organo Compounds of Ir(I) and Rh(I): Formation of Arylhydrido, Carboxylatohydrido, and Carboxylato Derivatives cis-Arylhydridoiridium(III) complexes IrH(Ar)(O₂CR)(CO)(PPh₃)₂ (R = Me: Ar = C₆H₅, 4-MeC₆H₄; R = Et: Ar = 4-MeC₆H₄, 2,4-Me₂C₆H₃) could be prepared by oxidative addition of carboxylic acids to aryliridium(I) compounds Ir(Ar)(CO)(PPh₃)₂. Reaction of aliphatic carboxylic acids with alkyliridium(I) derivatives Ir(Alk)(CO)(PPh₃)₂ and Ir(Alk)[PhP(CH₂CH₂CH₂PPh₂)₂] (Alk = CH₂CMe₃, CH₂SiMe₃) lead to dicarboxylatoiridium(III) hydrides IrH(O₂CR)₂(CO)(PPh₃)₂ (R = Me, Et, i-Pr) and IrH(O₂CR)₂[PhP(CH₂CH₂CH₂PPh₂)₂] (R = Me, Et). Ir(4-MeC₆H₄CO₂)(CO)(PPh₃)₂ was obtained from Ir(CH₂SiMe₃)(CO)(PPh₃)₂ and 4-MeC₆H₄CO₂H. Interaction of organorhodium complexes Rh(R′)(CO)(PPh₃)₂ (R′ = CH₂SiMe₃, 4-MeC₆H₄) and Rh(R′)[PhP(CH₂CH₂CH₂PPh₂)₂] (R′ = CH₂CMe₃, 4-MeC₆H₄) with aliphatic and aromatic carboxylic acids yielded carboxylatorhodium(I) compounds Rh(O₂CR)(CO)(PPh₃)₂ (R = Me, t-Bu, 4-MeC₆H₄) and Rh(O₂CR)[PhP(CH₂CH₂CH₂PPh₂)₂] (R = Me, 4-MeC₆H₄).     

Carbamoyl and alkoxycarbonyl complexes of palladium(II) and platinum(II)

Carbamoyl and alkoxycarbonyl complexes of palladium(II) and platinum(II) of the type M(pnp)(CONHR)Cl (pnp = 2,6-bis(diphenylphosphinomethyl)pyridine; M Pd, R  C₆H₅, p-CH₃C₆H₄, p-CH₃OC₆H₄, C₆H₁₁, t-Bu; M  Pt, R  C₆H₅), Pd(pnp)[CON(Pr)₂]Cl (Pr = propyl), M(pnp)(COOR)Cl (M  Pd, R  C₆H₅, CH₃; M  Pt, R  CH₃), Pd(pnp)(COOCH₃)₂ result from reaction of M(pnp)Cl₂ with carbon monoxide and amines or alkoxides at room temperature and atmospheric pressure.The carbamoyl complexes react with bases to give urethane or diphenylurea depending upon the experimental conditions.     

Studies on novel unsymmetrical azomethines—III : Copper(II) complexes of unsymmetrical tetradentate azomethines

Copper(II) complexes of unsymmetrical bifunctional tetradentate azomethines having the general formulae, (OC₁₀H₆CH:NXN:C(R)C₆H₄O)Cu, (OC₁₀H₆CH:NXN:C(CH₃)CHC(CH₃)OCu, (OC₆H₄CH:NXN:C(CH₃)C₆H₄O)Cu, (OC₆H₄C(R);NXN:C(CH₃)CHC(CH₃)O)Cu (where R = H or CH₃, X = (CH₂)₃, (CH₂)₄, (CH₂)₆ or -oC₆H₄) have been synthesized by the reactions of preformed mixed imine complexes of the type, CuLL′ (where L and L′ are two different imines such as 2-hydroxy-1-naphthaldimine, salicylaldimine, o-hydroxyacetophenonimine or acetylacetonimine) with diamines such as 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane or o-phenylenediamine. These complexes have been characterized by elemental analyses, TLC, conductance, magnetic measurements, IR and electronic spectra.     

Cyclobutadieneiron nitrosyl complexes

The air stable yellow-orange complexes of cyclobutadieneiron dicarbonyl nitrosyl hexafluorophosphate, [R₄C₄Fe(CO)₂NO]⁺PF^-₆; R = H, CH₃, Ph, were prepared by the reaction of R₄C₄Fe(CO)₃ and nitrosonium hexafluorophosphate. These complexes undergo facile monocarbonyl substitution reactions with various Lewis bases (L) to afford products of the type [R₄C₄Fe(CO)(NO)L]⁺PF^-₆, R = H, L = Ph₃P, Ph₃As, Ph₃Sb or R = Ph; L = Ph₃P, Ph₃As; a dicarbonyl substitution product of the type [R₄C₄Fe(NO)L₂]⁺PF^-₆, R = Ph; L = (PhO)₃P, was also isolated and characterized.     

Methyl- and phenyl-bis(tertiary phosphine) N-bonded carboxamido complexes of platinum(II)

Methyl- or phenylN-carboxamido-complexes of platinum(II) Pt(NHCOR')RL₂ (L = PEt₃, R = Me, R′ = Me, CH = CH₂; L = PEt₃, R = Ph, R′ = Me; L = PMe₂Ph, R = Ph, R′ = Me, Ph; L = PMePh₂, R = Ph, R′ =₃, R = Ph, R′ = Me) have been prepared by the reaction of KOH with cationic nitrile complexes [PtR(NCR′)L₂]BF₄. Thermally unstable hydrido-N-carboxamido-complexes could be detected spectroscopically. IR and NMR (¹H, ³¹P) spectra of some of the complexes indicate the existence of a solvent- and temperature-dependent equilibrium between syn-and anti-isomers arising from restricted rotation about the NC bond of the carboxamido-group. The anti-isomer is favoured by nonpolar solvents and by increasing bulk of L. In the complex [PtH(NCCH CH₂)(PEt₃)₂]BF₄, IR and NMR spectra show acrlonitrile to be bound through nitrogen, not through the olefinic CC bond.     

Effects of wavelength and substituents on iron(III) photoreduction in trans-[Fe(R-sal-R‵-en)(CH3OH)(NCS)] complexes

Photoredox reactions in irradiated methanolic solutions of trans-[Fe(R′-sal-R₂-en) (CH₃OH)(NCS)] complexes, where R′-sal-R₂-en^2? are tetradentate open-chain N,N′-1,1-R₂-ethylenebis(R′-salicylideneiminato) ligands (R?=?H or CH₃; R′?=?H, 5-Cl, 5-Br, 3,5-Br₂, 3-OCH₃, 4-OCH₃), have been explored and a mechanism suggested. The complexes are redox-stable in the dark in methanol. Continuous irradiation of solutions in the region of intraligand (IL) or ligand-to-metal charge transfer (LMCT) transitions leads to photoreduction of Fe(III) to Fe(II) and formation of formaldehyde (CH₂O). Formation of polystyrene-containing bonded NCS, when irradiating the complexes in the presence of styrene used as a radical scavenger, indicates that the primary photoreduction of Fe(III) to Fe(II) is accompanied by oxidation of NCS^? to the ^?NCS radical. R′-sal-R₂-en ligands have little effect on the photoinduced redox processes. The quantum yield of Fe(II) formation, Φ_Fe(II), as a quantitative parameter of photoredox efficiency, decreases significantly with increasing wavelength of incident radiation, and is slightly influenced by the peripheral groups, R, of R′-sal-R₂-en.     

The isocyanide-induced formation of dicyclopentadienyltantalummonoalkyl species from hydride olefin complexes

Reaction of endo Cp₂Ta(H)L (L = C₃H₆, C₄H₈ (1-butene)) with aryl- and alkyl-isocyanides R′NC (R′ = 2,6-(CH₃₂C₆H₃, cyclo-C₆H₁₁, CH₃ and t-C₄H₉) gives the thermally stable isocynaide adducts of Cp₂TaR (R = C₃H₇, C₄H₉). The extraordinarily strong metalisocyanide interaction leads to a non-linear “carbene-like” structure for these complexes and gives rise to the possibility of reactions at the nitrogen lone-pair electrons. The tantalocene isocyanide complexes react with Lewis acids, such as AlEt₃ to give 1/1 adducts Cp₂Tar · R′NC : AlEt₃.     

Verbindungen des Germainums und Zinns. 17. Alkylarylstannylen-Komplexe des Chroms und Molybdäns ohne Donorstabilisierung

Compounds of Germanium and Tin. 17 [1]. Alkylarylstannylene Complexes of Chromium and Molybdenum without Donor Stabilization Reaction of the complexes [(OC)₅M(THF)], M = Cr, Mo, with the alkylarylstannylene RR′Sn: R = 2,4,6-tBu₃C₆H₂, R′ = CH₂C(CH₃)₂-3,5-tBu₂C₆H₂, provides the donor-free stannylene complexes [(OC)₅Cr?SnRR′] ( 6 ) and [(OC)₅Mo?SnRR′] ( 8 ), respectively. The X-ray structure analyses of the isotypic compounds 6 and 8 reveal the three coordinate tin atoms in strictly planar environments and acute CSnC angles of 91.2° ( 6 ) and 91.3° ( 8 ).     

High-spin complexes of iron(III) with ethylene glycol and 3(2′-hydroxyphenyl)-5-(4′-substituted phenyl) pyrazolines

Complexes of iron(III) with ethylene glycol and 3(2′-hydroxyphenyl)-5-(4′-substituted phenyl) pyrazolines, [Fe(OCH₂CH₂O)(C₁₅H₁₂N₂OX)] _m ? nH₂O and [Fe(C₁₅H₁₂N₂OX)₂(OCH₂CH₂OH)] (where OCH₂CH₂O and OCH₂CH₂OH = ethylene glycol moiety; C₁₅H₁₂N₂OX = 3(2′-hydroxyphenyl)-5-(4-X-phenyl)pyrazoline; X = H, CH₃, OCH₃, or Cl; m = 2–3 and n = 2–3) have been synthesized and characterized by elemental analysis (C, H, N, Cl, and Fe), molecular weight measurement, magnetic moment data, thermogravimetric analysis, molar conductance, spectral (UV-Vis, IR, and FAB mass), scanning electron microscopy, and X-ray diffraction studies. Bonding of ethylene glycol and pyrazolines in these complexes and the particle size of iron(III) complexes are discussed. Antibacterial and antifungal potential of free pyrazoline and some iron(III) complexes are also discussed.     

Zur reaktion von metall-koordiniertem kohlenmonoxid mit yliden: XII. Eisenkomplexe mit η1-koordinierter vinylgruppe: spontane zweif achmethylierung des β-kohlenstoffs mit methyliodid oder methylfluorsulfonsäureerster

The reaction of vinyl complexes Cp(CO)(R₃P)FeC(OMe)CH₂ (R  Me, R  Ph) with the methylating reagents MeX (X  OSO₂F, I) in the molar ratio 1/1 affords a mixture of the carbene complexes [Cp(CO)(R₃P)FeC(OMe)R]X (R  Me, Et, i-Pr). Their formation is explained via a series of acid/base equilibria established between vinyl and carbene complexes.     

Optisch aktive übergangsmetall-komplexe LXIV. Neue optisch aktive Cp(CO)Fe-acyl-komplexe mit

The novel complexes CpFe(CO)(COR)P(C₆H₅)₂NR'R^* with Cp = C₅H₅,C₉H₇ (indenyl); R = CH₃, C₂H₅, CH(CH₃)₂, CH₂C₆H₅;R` = H, CH<sub>3</sub>, C<sub>2</sub>H<sub>5</sub>, CH<sub>2</sub>C<sub>6</sub>H<sub>5</sub> and R<sup>*</sup> = (S)-CH(CH<sub>3</sub>)(C<sub>6</sub>H<sub>5</sub>), have been synthesized by reaction of CpFe(CO)<sub>2</sub>R wiht P(C<sub>6</sub>H<sub>5</sub>)<sub>2</sub>NR`R^* and characterized analytically as well as spectroscopically. The pairs of diastereoisomers RS/SS have been separated by preparative liquid chromatography and fractional crystallization, respectively. The optically pure complexes (+)₄₃₆- und ()₄₃₆-CpFe(CO)(COR)P(C₆H₅)₂NR`R^* are configurationally stable at room temperature. At higher temperatures they equilibrate with CpFe(CO)₂R and epimerize with respect to the Fe configuration.