Reactivity of main-group—transition-metal bonds : VI. the kinetics of iodination of tetracarbonyl(trimethylstannyl)cobalt and pentacarbonyl(trimethylstannyl)rhenium

The kinetics of the iodine cleavage of the SnCo bond in [Me₃SnCo(CO)₄ ] and of the SnRe bond in [Me₃SnRe(CO)₅] have been measured. The order of rates of cleavage of the SnM bond in the compounds [Me₃SnM(CO)_x(cp)_y] (M = Mn, Re, x = 5, y = 0;M = Co, x = 4, y = 0; M = Cr, Mo, W, x = 3, y = 1; M = Fe, x = 2, y = 1; cp = η-cyclopentadienyl) indicates that the main factors determining reactivity towards iodine are the size of the metal atom (M) and the shielding of it by the other ligands.     

Bis(diphenylphosphano)alkan- und 1-(Diphenylphosphano)-2-(2-pyridino)ethan-N-Arylsulfinylamin-Nickel(0)-Komplexe

Bis(diphenylphosphano)alkane- and 1-Diphenylphosphano-2-(2-pyridino)ethane-N-arylsulfinylamine Nickel(0) Complexes Synthesis and properties of the bis(diphenylphosphano)alkane-N-phenyl-sulfinylamine-nickel(0) complexes [Ni{Ph₂P(CH₂)_nPPh₂}(PhNSO)] (n = 2 dppe, n = 3 dppp, n = 4 dppb) as well as of the 1-(diphenylphosphano)-2-(2-pyridino)ethane nickel(0) complexes [Ni(dpppe)₂], [Ni(dpppe)(p-TolNSO)] and [Ni(dpppe)(PPh₃)₂] are described. These compounds have been characterized by i. r. and ³¹P n.m.r. spectroscopy. The N-arylsulfinylamine ligands are η²-(N, S)-side on coordinated.     

Triphenylphosphan-Nickel(0)-Komplexe mit Isocyanid-Liganden — [(RNC)nNi(PPh3)4–n] (n = 1–3)

Triphenylphosphane Nickel(0) Complexes with Isocyanide Ligands — [(RNC)_nNi(PPh₃)_4–n] (n = 1–3) Synthesis and properties of the isocyanide triphenylphosphane nickel(0) complexes [(RNC)Ni(PPh₃)₃], [(RNC)₂Ni(PPh₃)₂] and [(RNC)₃Ni(PPh₃)] (R = ^tBu, Cy, PhCH₂, p-TosCH₂) are described. I.r. and ³¹P n.m.r. spectra were recorded and the X-ray crystal structure of [(PhCH₂NC)₂Ni(PPh₃)₂] was determined.     

Tb2–xNdxZn17–yNiy (x = 0.5, y = 4.83): a new intermetallic with a maximum disordered structure and its hydrogen storage properties

The ternary Tb_2–xNd_xZn_17–yNi_y (x = 0.5, y = 4.83) disordered phase belongs to the structural family based on the rhombohedral Th₂Zn₁₇ structure type. The structure is maximally disordered since all the sites are occupied by statistical mixtures of atoms. The Tb/Nd mixture of atoms occupies the 6c site (site symmetry 3m). The statistical mixtures Ni/Zn consisting of more Ni atoms are located in the 6c and 9d (symmetry .2/m) sites. In the following 18f (site symmetry .2) and 18h (site symmetry .m) sites are located Zn/Ni statistical mixtures which consist of more Zn atoms. Zn/Ni atoms form three-dimensional networks with hexagonal channels that fill statistical mixtures of Tb/Nd and Ni/Zn. The Tb_2–xNd_xZn_17–yNi_y compound belongs to the family of intermetallic phases capable of absorbing hydrogen. In the structure, there are three types of voids, namely, 9e (site symmetry .2/m), 3b (site symmetry m) and 36i (site symmetry 1), in which hydrogen can be inserted, and the maximum total absorption capacity can reach 1.21 wt% H₂. Electrochemical hydrogenation shows that the phase absorbs 1.03% of H₂, which indicates partial filling of the voids with H atoms.     

Structural studies of Rh4(CO)12 derivatives in solution and in the solid state

The crystal structures of Rh₄(CO)₁₀(PPh₃)₂ and Rh₄(CO)₉P(OPh)₃₃ are reported. ³¹P-¹H NMR studies on Rh₄(CO)₁₂-_x {P(OPh)₃}_x(X  1, 2 and 3) show that each derivative exists as only one isomer in solution whereas the analogous triphenylphosphine derivatives can exist as different isomers. A quantitative redistribution of triphenylphosphites occurs on mixing Rh_4-(CO)₁₂-_xL_x with Rh₄(CO)₁₂-_yL_y (L  P(OPh)₃; x  0, 1, 2, y  x + 2; x  0, y  x + 4) to give Rh₄(CO)₁₂-_zL_z[z $\text{1}\text{2}$(x + y)]; a related rapid intermolecular randomisation of carbonyls occurs on mixing Rh₄(¹²CO)₁₂ with Rh₄(¹³CO)₁₂.     

Nitrido-Sodalithe. II. Synthese,Struktur und Eigenschaften von M(6+(y/2)–x)H2x[P12N24]Zy mit M = Fe,Co, Ni,Mn; Z = Cl,Br, I; 0 ≤ x ≤ 4; y ≤ 2

Nitrido-Sodalites. II. Synthesis, Crystal Structure, and Properties of M_{(6+(y/2)–x)}H_2x[P₁₂N₂₄]Z_y with M = Fe, Co, Ni, Mn; Z = Cl, Br, I; 0 ≤ x ≤ 4; y ≤ 2 The nitrido sodalites M_{(6+(y/2)–x)}H_2x[P₁₂N₂₄]Z_y with M = Fe, Co, Ni, Mn; Z = Cl, Br, I; 0 ≤ x ≤ 4; y ≤ 2 are obtained by the reaction of HPN₂ or [PN(NH₂)₂]₃ with the metal halogenide MZ₂ (T = 700°C). The compounds are isotypic to Zn_(7–x)H_2x[P₁₂N₂₄]Cl₂. An increase of the ionic radii of the cations or anions results in an expansion of the lattice which is caused by an increase of the P? N? P angle. The influence of the cation is more dominant than that of the anion. By reacting [PN(NH₂)₂]₃ with metal halogenide (MZ₂) hydrogen free, X-ray amorphous products are obtained. The formation of the chloride-containing P? N-sodalite in this reaction begins at temperatures below 450°C.     

Organometallchemie binuclearer 1-Azadien-nickel(0)-Komplexe Bimetallverbindungen mit Ni?Fe-Bindung durch Addition von Pentacarbonyleisen(0) und Nickelalactone durch Ringöffnung cyclischer Anhydride

Organometallic Chemistry of Binuclear 1-Azadiene-Nickel(0) Complexes: Bimetallic Compounds with a Ni? Fe Bond by Addition of Pentacarbonyl-iron(0) and Nickelalactons by Ring Opening Reaction of Cyclic Anhydrides The binuclear nickel(0) complexes 1–3 , which contain as well bridging 1-azadienes ligands as five or six-membered (N∩N)-chelate rings react at ?30°C with Fe(CO)₅ to form the bimetallic compounds 4–6 , containing a Ni? Fe bond and two carbonyl groups as bridging ligands. The coordination of the [(bpy)Ni(0)] fragment to the olefin part of the 1-azadiene chain in 6 leads to the formation of the trinuclear complex 7 , which can storage CO₂ at the peripheral position. Succinic acid anhydride or glutaric acid anhydrid undergo a ring opening reaction by reacting with 3 yield nickelalactones upon elimination of CO.     

Ni-based catalysts obtained from perovskites oxides for ethanol steam reforming

Perovskites as host structures of cations were used in order to generate in situ active and stable catalysts for ethanol steam reforming. For this purpose, La_1-xMg_xAl_1-yNi_yO₃ (x = 0.1; y= 0, 0.1, 0.2, 0.3) perovskites were synthetized by the citrate method. Ni segregation is evident for a substitution level higher than 0.2. The segregation of Ni as NiO generated species interacts with different metal-support after the reduction step. The y= 0.1 catalyst presents the highest H₂ yield value about 85% during reaction time, with low mean values of CH₄ and CO selectivities of 3.4% and 11%, respectively and a low carbon formation. The better performance of y= 0.1 catalyst could be attributed to the minor proportion of segregated phases, thus a controlled expulsion of Ni is successfully reached.     

Fluoraustauschreaktionen an Metalltrifluorphosphan-Komplexen. X [1]. Zum Reaktionsverhalten von Tetrakis(trifluorphosphan)-nickel(0) mit Metallorganylen [2]

Ni(PF₃)₄ ( 1 ) tauscht mit Lithiumorganylen und Grignard-Reagentien Fluor gegen Organyl-Gruppen aus, wobei die Komplexe ( 10–32 ) Ni(PF₃)_4?n(PF₂R)_n (n = 1, 2 und 3), Ni(PF₃)₃(PFR₂), Ni(PF₃)₂(PF₂R)(PFR₂) und Ni(PF₃)₃(PR₃) (R = organ. Rest) gebildet werden. Für den Reaktionsablauf wird ein Vierzentren-Synchron-Mechanismus vorgeschlagen. Fluorine Exchange in Trifluorophosphane Metal Complexes. X. Reactions of Tetrakis(trifluorophosphane)nickel(0) with Metal Organyls The fluorine atoms in Ni(PF₃)₄ ( 1 ) can be partially substituted by organyl groups yielding the complexes ( 10–32 ) Ni(PF₃)_4?n(PF₂R)_n (n = 1, 2 and 3), Ni(PF₃)₃(PFR₂), Ni(PF₃)₂(PF₂R)(PFR₂) and Ni(PF₃)₃(PR₃) (R = organyl group). The mechanism of these peripheric reactions is discussed by assuming a four centered type intermediate.     

Formation of mixed Fe-Mo oxo clusters in the gas phase

Reactions of oxygen-containing molybdenum clusters Mo_xO_y (x = 1–3, y = 1–9) with iron carbonyl ions Fe(CO) _n ⁺ (n = 1–3) were studied by the ion cyclotron resonance technique. The reactions were found to yield mixed Fe-Mo oxo clusters Mo_xO_yFe⁺ (x = 2, 3; y = 5, 6, 8, 9).     

Perfluormethyl-Element-Liganden. XVIII. Darstellung und spektroskopische Untersuchung von M(CO)5L und M(CO)4L2-Komplexen [L = MenP(CF3)3−n; n = 0–3; M = Cr,Mo, W]

Perfluoromethyl-Element-Ligands. XVIII. Preparation and Spectroscopic Investigation of M(CO)₅L and M(CO)₄L₂ Complexes [L = Me_nP(CF₃)_3?n; n = 0–3; M = Cr, Mo, W] M(CO)₅L and cis-M(CO)₄L₂ complexes, respectively [M = Cr, Mo, W; L = Me_nP(CF₃)_3?n; n = 0–3] are prepared reacting M(CO)₅ · THF or M(CO)₄norbor with L at room temperature. The cis-compounds isomerize above 50°C yielding the trans-complexes; the rate of isomerization increases with increasing number of CF₃ groups. Thermal reaction of M(CO)₆ (M = Cr, Mo, W) with P(CF₃)₃ yields M(CO)₅P(CF₃)₃ and trans-M(CO)₄[P(CF₃)₃]₂. Introduction of three P(CF₃)₃ ligands by reaction with M(CO)₃(cycloheptatriene) (M = Cr, Mo) proves unsuccessful; besides little M(CO)₅P(CF₃)₃ trans-M(CO)₄[P(CF₃)₃]₂ is formed. The new compounds are characterized by analytical and spectroscopic (n.m.r., i.r., MS) methods.     

Spectroscopic studies of manganese(II) and zinc(II) complexes of 1-phenyl-3-methyl-4-acylpyrazolone-5

Mn(II) and Zn(II) complexes of a series of 4-acyl derivatives of 1-phenyl-3-methylpyrazolone-5 have been synthesized. Characterization was by elemental analyses, UV, IR and ¹H NMR analyses. The chelates were found to conform to a general molecular formula ML₂·xCH₃CH₂OH·yH₂O where M = Mn, Zn; L is the acylpyrazolone-5 anion; x = 0, 1 or 2; and y = 0, 1 or 2. Spectral analyses showed that the adducts associated with the complexes have no effect on the bathochromic shifts observed in the UV and IR spectral properties of the complexes. The stability of the C

O and COM bonds does not follow any regular pattern with respect to the carbon chain of the 4-acyl substituent. The Mn(II) complexes have μ_eff values within the range of 5.3–5.6 B.M.     

Thermal Behaviour of the N-donor Adducts of Metal Saccharinates. II. 1,10-phenanthroline saccharinato complexes of Co(II), Ni(II), Cu(II), Zn(II) and Pb(II)

Adducts of Co(II), Ni(II), Cu(II), Zn(II) and Pb(II) saccharinates with 1,10-phenathroline were synthesized and their thermoanalytical (TG, DTG and DTA) curves in the 20–1000°C temperature interval and static air atmosphere were recorded. The complexes are best represented as M(C₁₂H₈N₂)_x(C₇H₄NO₃S)₂⋅yH₂O (x=2, 2, 2, 2 and 1; y=1, 1, 2, 1 and 2 for M=Co, Ni, Cu, Zn and Pb, respectively). The decomposition of the compounds regularly started with dehydration, followed by loss of the phenanthroline ligand(s). The structures of the Cu and Pb complexes are notably different from other compounds. FTIR spectra of the title compounds in the region of the OH, CO and SO₂ stretching vibrations were also studied. The pronounced similarity of the spectra of Co, Ni and Zn adducts indicates possible isomorphism among them. This revised version was published online in July 2006 with corrections to the Cover Date.     

Komplexchemie P‐reicher Phosphane und Silylphosphane. XXV. Bildung und Struktur des [{cyclo‐P3(PtBu2)3}{Ni(CO)2}{Ni(CO)3}]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXV. Formation and Structure of [{ cyclo ‐P₃(P^tBu₂)₃}{Ni(CO)₂}{Ni(CO)₃}] ^tBu₂P–P=P(R)^tBu₂ (R = Br, Me) reacts with [Ni(CO)₄] yielding [{cyclo‐P₃(P^tBu₂)₃}{Ni(CO)₂}{Ni(CO)₃}]. The two cis‐^tBu₂P substituents of the cyclotriphosphane, which results from the trimerization of the phosphinophosphinidene ^tBu₂P–P, are coordinating to a Ni(CO)₂ unit forming a five‐membered P₄Ni chelate ring. The trans‐^tBu₂P group is linked to a Ni(CO)₃ unit. The compound crystallizes in the orthorhombic space group Pbca (No. 61) with a = 933.30(5), b = 2353.2(1) and c = 3474.7(3) pm.     

THE EPR SPECTRA OF TETRADENTATE SCHIFF BASE COMPLEXES OF COPPER (II) I. N,N'-Bis-(acetylacetone) ethylenediimine and N,N'-Bis-(1,1,1-trifluoroacetylacetone) ethylenediimine

Abstract

The EPR spectrum of N, N'-bis-(acetylacetone)ethylenediimino Cu(II), [Cu-en(acac)₂], and N, N'-bis-(1,1,1-trifluoroacetylacetone)ethylenediimino-Cu(II), [Cu-en(tfacac)₂], have been studied in doped single crystals of the corresponding Ni(II) chelate. The parameters in the usual doublet spin-Hamiltonian are found to be: Cu[en(acac)₂], g_z =2.183 ± 0.003, g_x =2.047 ± 0.004, g_y =2.048 ± 0.004, A_z =204.8 × 10^?4cm^?1, A_x =31.5 × 10^?4cm^?1, A_y =27.1 × 10^?4 cm^?1, A_zN= 12.8 × 10^?4 cm^?1 and A_xN =A_yN =14.3 × 10^?4 cm^?1: Cu[en(tfacac)₂], g_z =2.192 ± 0.002, g_x =2.048 ± 0.004, g_y =2.046 ± 0.004, A_z =200.8 × 10^?4 cm^?1, A_x =31.1 × 10^?4 cm^?1, A_y =28.3 × 10^?4 cm^?1, A_zN =12.8 × 10^?4 cm^?1 and A_xN =A_yN =14.6 × 10^?4 cm^?1. These parameters are related to coefficients in the molecular orbitals of the complex. It is found that the α-bonding is quite covalent and there is significant in-plane σ-bonding. From the nitrogen hyperfine structure it is determined that the hybridization on the nitrogen is sp².     

(Fluoroalkyl)phosphine complexes of nickel(0) and cobalt(I)

The synthesis of a series of (fluoroalkyl)phosphine complexes of nickel is reported. Treatment of (cod)₂Ni with dfepe (dfepe=(C₂F₅)₂PCH₂CH₂P(C₂F₅)₂) yields (dfepe)Ni(cod) (1), which has been structurally characterized. Treatment of 1 with CO or bipy results in the formation of (dfepe)Ni(CO)₂ (2) and (dfepe)Ni(bipy) (3), respectively. Addition of excess dfepe to 1 results in incomplete cod displacement to form (dfepe)₂Ni (4). The homoleptic complex 4 may be independently prepared in high yield by reduction of (acac)₂Ni with (ⁱBu)₃Al in the presence of butadiene and excess dfepe. Solvation of (dfepe)Ni(cod) in acetonitrile gives a new complex tentatively identified as (dfepe)Ni(MeCN)₂ (6), whereas dissolution of (dfepe)₂Ni in acetonitrile leads to a mixture of 6 and the partial displacement product (dfepe)(η¹-dfepe)Ni(MeCN) (5). In contrast to (R₃P)₄Ni(0) phosphine and phosphite complexes, which undergo protonation by strong anhydrous acids such as HCl, H₂SO₄ and CF₃CO₂H to give (R₃P)₄Ni(H)⁺ products, Treatment of (dfepe)₂Ni with neat CF₃CO₂H or excess HOTf in dichloromethane gave no spectroscopic evidence for (dfepe)₂Ni(H)⁺. Exposure for extended periods leads to dfepe loss and decomposition to Ni(II) products. The synthesis of the first cobalt complex of dfepe, (dfepe)Co(CO)₂H, is also reported.     

Fluoraustauschreaktionen an Metalltrifluorphosphin-Komplexen. IX. Zum Reaktionsverhalten von Tetrakis(trifluorphosphin)nickel(0) gegenüber Alkyl(trimethylsilyl)aminen und -amiden

Fluorine Exchange in Trifluorophosphine Metal Complexes. IX¹. (Reactions of Tetrakis(trifluorophosphine)nickel(0) with Alkyl(trimethylsilyl)amines and Amides²) Alkylaminodifluorophosphine complexes Ni(PF₃)_4-n(PF₂NHR)_n (n = 1, 2, 3) 8–11 and Me₃SiF are obtained, if alkyl(trimethylsilyl)amines NHR(SiMe₃) (R?CH₃ and n-C₄H₉) are reacted with Ni(PF₃)₄ ( 1 ). The mechanism of these peripheric reactions is discussed by assuming a four centered type intermediate. However reactions of 1 with the lithium amides LiNR(SiMe₃) (R = CH₃, C₂H₅, n-C₄H₉, and C₆H₅) yield LiF and the difluorotrimethylsilylaminophosphine complexes Ni(PF₃)_4-n[PF₂NR(SiMe₃)]_n (n = 1, 3, 4) 12–18 .     

Counterdisproportionation between cationic Ni(II) and phosphine Ni(0) complexes

The interaction of Ni(II) bis-tetrafluoroborate complexes [Ni(Dppe)₂](BF₄)₂ and [Ni(CH₃CN)₆](BF₄)₂ (where Dppe = 1,2-bis(diphenylphosphino)ethane)) with Ni(0) phosphine complexes Ni(Dppe)₂ and Ni(PPh₃)₄ in 1 : 1 mixture of toluene-acetonitrile was studied by the EPR method. The counter-disproportionation was shown to occur in a solution between the cationic Ni(II) complexes and the Ni(0) complexes to give Ni(I) complexes almost in quantitative amounts. The structures of the cationic Ni(I) complexes obtained were found to depend on both the solvent nature and the presence of a free phosphine in a solution.     

Reaktionen von Gemischtligand-Komplexen des Nickel(0) mit Kohlenstoffdichalcogeniden

Reactions of Mixed Ligand Complexes of Nickel(0) with Carbon Dichalcogenides Decisive for the occurrence of a reaction between mixed ligand complexes of nickel(0) and carbon dichalcogenides is the HOMO-energy of the complex and the LUMO-energy of the reagent, which are reflected in the corresponding polarographic half-wave potentials. Therefore, (dipy)-Ni(COD) is substituted by SeCS, CS₂ and SCO, whereas (PPh₃)₂Ni(C₂H₄) only reacts with CS₂, but not with SCO. Substitution by CO₂ needs substrates like Ni(PCy₃)₃ or Ni(PEt₃)₄ which have the lowest anodic waves. (PCy₃)₂Ni(C₂H₄) and (dipy)Ni(PPh₃)₂ effect C?S-bond breaking in SCO, and mixed carbonyls, such as (PCy₃)₂Ni(CO)₂ or (PPh₃)₂Ni(CO)₂, are formed. Futher products are dithiocarbonates or oligonuclear nickel sulfides which are stabilized by a phosphine. Another oligonuclear complex, (PPh₃)₂Ni₃(CS₂)₂, is formed by the reaction of CS₂ with surplus (PPh₃)₂Ni(C₂H₄). The function of CS₂ is that of a bridging ligand. The carbon dichalcogenides are side-on (η²) coordinated in compounds like (dipy)Ni(CS₂), (PPh₃)Ni(CS₂) and (dipy)Ni(SCO). It is always the highest electronegative heteroatom of the non symmetric ligands SeCS and SCO which does not interact with the central atom.     

Study of the chemical structure and the microbial effect of iron(III) metal ions with four consecutive generations of quinolones in a nanometric form for the purpose of increasing the efficacy of antibacterial and antifungal drugs

A new series of iron(III) complexes with different fourth generation of quinolone drugs of the type [Fe(L)_n(Cl)_x]?yH₂O (( 1 ) L: nalidixic acid, n = 3, x = 3, y = 3; ( 2 ) L: oxolonic acid, n = 3, x = 3, y = 0; ( 3 ) L: pipemidic acid, n = 3, x = 3, y = 2; ( 4 ) L: lomefloxacin, n = 3, x = 3, y = 0; ( 5 ) L: pefloxacin mesylate, n = 3, x = 3, y = 2; ( 6 ) L: levofloxacin, n = 3, x = 3, y = 6) were synthesized and identified using microanalysis, Fourier transform infrared spectroscopy, conductance data, effective magnetic moments and electronic UV–visible spectra. In these six complexes, the quinolone drug chelates act in a unidentate manner via nitrogen atom of pyridone/piperazyl moiety. Electronic spectroscopic data are in agreement with an octahedral geometrical structure. Thermal degradation analyses in nitrogen gas were used to investigate the number and location of water molecules. The thermal decomposition process is completed in 3?5 steps, the first step being responsible for loss of uncoordinated water molecules and the steady state of all complexes occurs at around 500 °C with oxide forms as residual products. The stabilities of iron(III) complexes 1 – 6 were studied in terms of activation energy E*, entropy ΔS*, enthalpy ΔH* and Gibbs free energy ΔG* that were estimated using Coats–Redfern and Horowitz–Metzger non‐isothermal methods. Molecular docking was used to predict the binding between some of the quinolone drugs and the receptor of prostate cancer 2q7k hormone.