Salicylaldehydo chelates of bis(cyclopentadienyl) zirconium(IV)

A new series of organometallic ionic chelates of the type [Cp ₂Zr(sal)]⁺ [ROCS₂/RRNCS₂]^–, where Hsal = salicylaldehyde;R =Me, Et, i-Pr ori-Bu andR =R =Me, Et, i-Pr;R =Me,R = benzyl orR =Et,R =m-tolyl, have been synthesized in aqueous medium by the reaction of [Cp ₂Zr(sal)]⁺Cl^– andROCS ₂ ^– K⁺/RRNCS ₂ ^– Na⁺. These compounds have been characterized by chemical analyses, electrical conductance, electronic, IR and¹H-NMR spectral studies. These studies indicate that the complexes are 1:1 electrolytes and the salicylaldehyde ligand is chelating in all these complexes. Therefore, a tetrahedral coordination about the zirconium atom is proposed.

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Salicylaldehydo-Chelate von Bis(cyclopentadienyl)-zirkonium(IV)

Zusammenfassung Eine neue Gruppe von organometallischen ionischen Chelaten vom Typ [Cp ₂Zr(sal)]⁺ [ROCS₂/RRNCS₂]^– (mit Hsal = Salicyladehyd;R =Me, Et, i-Pr oderi-Bu undR =R =Me, Et, i-Pr;R =Me,R = Benzyl oderR =Et,R =m-Tolyl) wurde in wäßrigem Medium mittels der Reaktion von [Cp ₂Zr(sal)]⁺Cl^– mitROCS ₂ ^– K⁺/RRNCS ₂ ^– Na⁺ hergestellt. Die erhaltenen Verbindungen wurden mittels chemischer Analyse, elektrischer Leitfähigkeit und der IR- sowie¹H-NMR-Spektren charakterisiert. Diese Untersuchungen zeigen, daß die Komplexe 1:1-Elektrolyte sind, wobei der Salicylaldehyd-Ligand in allen Fällen an der Chelatbildung beteiligt ist. Es wird daher für das Zirkoniumatom eine tetrahedrale Koordination vorgeschlagen.

     

Cationic β-diketonato molybdenum nitrosyl complexes: redox and structural properties

Summary -Diketones react with [Mo(NO){HB(dmpz)₃}I₂] [HB (dmpz)₃ = tris (3,5-dimethylpyrazolyl)borate] giving the cationic complexes [Mo(NO) {HB(dmpz)₃}{OC(R)CRC-(R)O}]⁺ (R = R = Me, R = H, Me or n-Bu; R = R = Ph, R = H; R = Me, R = n-Bu, R = H), isolated as triiodide salts. Electrochemical studies show that these complexes exhibit three electrode processes: two associated with oxidation of I _inf3 ^sup– and one with reduction of the metal-containing cation. Reduction of the cation where R = R = R = Me with cobaltocene afforded the neutral paramagnetic [Mo(NO) {HB(dmpz)₃} {OC(Me)CMeC(Me)O}], which was characterized by i.r. and e.p.r. spectroscopy. In contrast, 3-chloropentane-2, 4-dione reacts efficiently with [Mo(NO){HB(dmpz)₃}I₂] giving the known chloro-analogue, [Mo(NO)-{HB(dmpz)₃}Cl₂], and no -diketonate complex was detected. The X-ray crystal structure determination of [Mo(NO){HB(dmpz)₃} {OC(Me)CMeC(Me)O}]I₃ confirms that the cation is six-coordinate and shows that the 559-01 (diketonate) bonds are slightly longer than in comparable compounds, implying that the -diketonate ligand is not such a strong -donor as alkoxide groups.     

Ethene polymerization with mixed-ring metallocene catalysts,Cp′Cp″MCl2, M = Ti and Zr

Mixed-ring metallocenes CpCpMCl₂ (Cp and Cp = cyclopentadienyl and its substituted derivatives; M = Ti and Zr) have been prepared by reacting CpMCl₃ with the Cp anion salt, in which the Cp–M bond is stronger than the Cp–M bond. Ethene has been polymerized with these complexes in the presence of methyl aluminoxane (MAO) as co-catalyst. The catalytic properties of titanocenes were influenced mainly by the steric effects of cyclopentadienyl ring substituents. Both steric and electronic effects of substituents influenced the catalytic properties of zirconocenes.     

Organometallic complexes containing thiosemicarbazone and related ligands. Part II(1). η3-allyl dicarbonyl complexes of molybdenum(II) with attached thiosemicarbazone ligands

Summary The -allylmolybdenum(II) complexes [MoX(CO)₂-(NCMe)₂(³-C₃H₄R)] (X=Cl, Br and I; R=H and 2-Me) react either in dichloromethane or acetonitrile with thiosemicarbazones to give the new complexes [MoX-(CO)₂(RRCNNHCSNH₂)(³-C₃H₄R)] (R=H or Me; R'=Me, Et, Pr or Ph)via displacement of acetonitrile ligands.     

Pseudohalogenverbindungen, 13. Mitt.

Zusammenfassung Der Halogenaustausch zwischen festem AgCl und einer Reihe von flüssigen Organosulfenylchloriden des Typs RRRCSCl (R, R, R=F, Cl, CF₃, CF₃S) wurde mit Hilfe von radioaktivem³⁶Cl untersucht. Die Ergebnisse deuten darauf hin, daß stark elektronegative Substituenten R, R und R eine Polarisierung der S–Cl-Bindung in den Sulfenylchloriden induzieren und dadurch die heterolytische Reaktivität dieser Bindung erhöhen.

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Heterogeneous³⁶ Cl exchange between halogenated organosulphenyl chlorides and silver chloride

The halogen exchange between solid AgCl and a number of liquid organosulphenyl chlorides of the type RRRCSCl (R, R, R=F, Cl, CF₃, CF₃S) has been studied using³⁶Cl as a tracer. On the basis of the results it is suggested that highly electronegative substituents R, R and R, by polarizing the S–Cl bonds in the sulphenyl chlorides, favour the heterolytic reactivity of these bonds.

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Mit 3 Abbildungen

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12. Mitt. vgl.A. Haas undH. Reinke, Chem. Ber.102, 2718 (1969).     

Ethane hydrogenolysis on silica-supported tantalum hydride. Quantum-chemical study

The structures of the (H₄Si₂O₅)O₂Ta(R, RR"R, RR) clusters (R, R", R = H, Me, Et, Pr; R = CH₂), which model the basic structural units of the catalytic cycle of ethane hydrogenolysis on silica-supported tantalum hydride, were studied by the density functional theory (B3LYP) and the perturbation theory (MP2). The possible structure of active sites was proposed based on comparison of experimental results with calculated data. Ethane hydrogenolysis and metathesis proceed by a mechanism involving the formation of ethylene -complexes and carbenium derivatives of tantalum as intermediates.     

Kinetics and mechanism of nucleophilic substitution of dichloro{1-methyl-2-(arylazo)imidazole}palladium(II) by pyridine bases

The reaction of dichloro{1-methyl-2-(arylazo)imidazole}palladium(II), Pd(RaaiMe)Cl₂ where RaaiMe = p-R–C₆H₄N=N–C₃H₂N₂-1-Me; R = H(1), Me(2), Cl(3), with pyridine bases [RPY: R = H (a), 4-Me (b), 4-Cl (c), 2-Me (d), 2,6-Me₂ (e), 2,4,6-Me₃ (f)] has been studied spectrophotometrically in MeCN at 451 nm. The products (4) have been isolated and characterised as trans-Pd(RPy)₂Cl₂. The kinetics of the nucleophilic substitution has been examined under pseudo-first-order conditions at 298 K. A single phase reaction step has been observed for bases such as Hpy (a), 4-MePy (b) and 4-ClPy (c) and follows the rate law: rate = (a + k[RPy]²[Pd(RaaiMe)Cl₂]). The bases 2-MePy (d), 2,6-Me₂Py (e) and 2,4,6-Me₃Py (f) exhibits a bi-phasic reaction and follows the rate laws: rate–1 = (a + k[RPy][Pd(RaaiMe)Cl₂]) and rate–2 = (a + k[RPy][Pd(RaaiMe)-Cl₂]), where k is the third-order rate constant; k is the second-order first phase rate constant, k is the second-order second phase rate constant and a/a/a correspond to the solvent dependent constant of the respective reaction path. The rate data supports a nucleophilic association path. External addition of Cl^– (LiCl) suppresses the rate, which follows the order: k/k/k (3) > k/k,k (1) > k/k,k (2). The k values are linearly related to the Hammett constants. The 2-substituted pyridines (d–f) remarkably reduce the rate and show a bi-phasic reaction behaviour as compared with 4-Rpy (a–c). This is attributed to the steric effect that destabilises the transition state. The rate decreases with increasing steric crowding at the ortho-position and follows the order: (d) > (f) > (e). The 4-substituted pyridines control the rate via an inductive effect and follow the order: (b) > (a) > (c).     

Reactions of α-halo-α, β-unsaturated aldehydes with secondary amines

Reactions of 2-halo-2-alkenals R(R)C=CX-CHO with secondary amines R₂NH occur asipso-substitution of the halogen atom, along with fragmentation and condensation, yielding 1,2-diaminoethenes R₂NCH=CHNR₂, carbonyl compounds RC(O)R, 1,3-bis(amino)-2-haloolefins R(R)C(NR₂)CX=CHNR₂, and formamides R₂NCHO. The ratio between the competing reactions depends on the structure of the starting compounds and the experimental conditions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp, 135–138, January, I996.     

Symmetrische,gemischt substituierte Trisilylamine (RR′R″Si)3N

Zusammenfassung Gemischt substituierte Disilylamine (RRRSi)₂NH lassen sich von NaNH₂ zu reaktionsfähigen Natrium-bis-(silyl)-amiden metallieren, aus denen nach Umsetzung mit Organohalogensilanen und anschließender Alkoholyse der verbleibenden Si-Cl-Gruppen gemischt substituierte Trisilylamine (RRRSi)₃N mit R=(me), R, R=O(me); R,R=(me), R=O(et); R=(vi), R, R=O(me); R=(me), R=(vi), R=O(ⁱpr) dargestellt werden konnten.33. Mitt.:U. Wannagat, J. Pump undH. Bürger, Mh. Chem.94, 1013 (1963).Auszüge aus den DissertationenH. Bürger, TH Aachen 1962,P. Geymayer, TH Graz 1963, und der DiplomarbeitG. Torper, TH Graz 1962; vgl. auchU. Wannagat undH. Bürger, Angew. Chem.75, 95 (1963).     

Isocyanide complexes of rhodium,part 31,2. Tetrakisisocyanide species four- and five-coordinate mixed isocyanide-tertiary phosphine complexes,and some oxidative-additions

Summary The complexes [Rh(CNR)₄][PF₆] (R = Et, C₆H₁₁,-NH₂C₆H₄ or I-C₁₀H₇),trans-[Rh(CNR)₂(PRR ₂ ^" )₂][PF₆] (R = R = Ph, R = Et, C₆H₁₁, -NH₂C₆H₄ or 1-C₁₀H₇; R= Me, R = Ph or R= Ph, R= Me, R= 1-C₁₀H₇) and [Rh(CNR)₃(PPh₃)₂][PF₆] (R = Me, Et or C₆H₁₁) have been prepared by treatment of [Rh(CO)₂Cl]₂ or Rh(CO)(PPh₃)₂Cl with RNC, or of [Rh(CNC₁₀H₇)₄][PF₆] with PRR₂ (R, R = Me, Ph). Addition of -ClC₆H₄NC to [Rh(CNEt)₂(PPh₃)₂][PF₆] gives [Rh(CNEt)₂(CNC₆H₄Cl-)(PPh₃)₂][PF₆]. Reactions of [Rh(CNR)₄][PF₆] and [Rh(CNR)₂(PPh₃)₂][PF₆] (R = Me, Et, C₆H₁₁ or 1-C₁₀H₇) with halogens, MeI, McCOCl, CF₃I, HgCl₂ and SO₂, are discussed briefly. The i.r. and¹H n.m.r. spectra show that the products aretrans-[ Rh(CNR)₄XY][PF₆] andtrans-[Rh(CNR)₂(PPh₃)2XY][PF₆].     

Ruthenium(ii) complexes with tetra-15-crown-5-phthalocyanine: synthesis and spectroscopic investigation

The ruthenium complexes with tetra-15-crown-5-phthalocyanine and various axial ligands were synthesized and characterized by spectroscopy. A method for the synthesis of bisaxially coordinated ruthenium(ii) tetra-15-crown-5-phthalocyaninates with the N-donor ligands (R₄Pc)Ru(L₂) (R₄Pc^2– = [4,5,4",5",4,5,4,5-tetrakis(1,4,7,10,13-pentaoxotridecamethylene)phthalocyaninate-ion], L is trimethylamine (Me₃N), pyridine (py), isoquinoline (iqnl), triethylamine (Et₃N), pyrazine (pyz)) was developed. The preparation technique involves selective decarbonylation of (R₄Pc)Ru(CO)(MeOH) on treatment with Me₃NO in excess N-donor solvent.     

Synthesis,crystal structure and reaction of differentially ring-substituted titanocene dichlorides

Summary A new class of differentially ring-substituted titanocene dichlorides of the type CpCpTiCl₂ has been prepared by reacting CpM (M=Li, K; Cp=RC₅H₄) with CpTiCl₃ (Cp=MeOCH₂CH₂C₅H₄). The crystal structure of Cp(PhCEt₂C₅H₄)TiCl₂, the first example, has been determined by x-ray diffraction and refined to a final R factor of 0.0532 for 2304 reflections. The crystal belongs to the monoclinic space group C _2h ⁵ –P2₁/c with unit cell parameters:a 10.205(6),b 13.003(5),c 17.591(9) Å, 101.91(4)°, V=2284 ų, Z=4 and Dc=1.32 g/cm^–3. Replacement of one neomenthyl in bis(neomenthyl-cyclopentadienyl)titanium dichloride by one MeOCH₂CH₂ — raises the e.e. value from 5.8% to 11.2% in the catalytic asymmetric hydrogenation of 2-phenyl-1-butene.     

Dynamics of the formation and decay of C2(a 3II u,v″=0) radical in a pulse discharge in methane

The plasma of a pulse discharge (0.05 J/cm³) in methane at low pressure (200 Pa) is studied. The dynamics of formation and decay of C₂(a³II_u, v=0) is monitored using a stroboscopic laser absorption method. It was found that substantial amounts of C₂, 10¹⁵ cm^–3, arise with a 1-µs delay after the current pulse.Notation _v absorption coefficient - wave number, cm^–1 - e electron charge - c velocity of light - h Planck's constant - m _e mass of electron - N _v concentration of molecules in the vibrational level v - f oscillator strength - l plasma column length - q _vv Franck-Condon factor - S _JJ Hönl-London factor - Q _rot rotational partition function - F(J) rotational term, cm^–1 - I _sig signal beam intensity - I _ref reference beam intensity - higher state index - lower state index - decay constant     

Microcalorimetric Evaluation of Precipitation in Cu–2Be–0.2Mg

Beryllium precipitation from the Cu-rich matrix in a Cu–2 mass% Be–0.2 mass% Mg alloy homogenized and quenched from 1073 K was studied by differential scanning calorimetry (DSC). The DSC traces showed two main exothermic effects, A and B, each comprising two subeffects: A₁ and A₂ , and B₁ and B₂ respectively. Effects A₁ and A₂ correspond to the precipitation of GP zones and subsequent overlapping and independent precipitation of the phase. Only at very low heating rates can be inherited from GP zones. Effects B₁ and B₂ correspond to heat evolved during transitions to the states with and phases, respectively. Heat effect A can be quantitatively described in terms of solid solubilities before and after precipitation, and of the precipitation heats of the phases involved. The heat content of the combined GP zone/ phase precipitation effect was proportional to the number of beryllium atoms precipitated, yielding an average value of 21 kJ mol^–1 beryllium for beryllium precipitation. It was shown that the phase arises from the combined transition from states with GP zones and phases, whereas arises from the transition of states with and phases. The apparent activation energies associated with GP zones and , and phases are 1.16±0.08, 1.18±0.07, 1.37±0.08 and 1.74±0.09 eV, respectively. These values are discussed in terms of the mobility of dissolved atoms related to the concentrations of excess vacancies and solute-vacancy complexes, and the direction of plate-like precipitate growth (either normal or perpendicular to the plate). It is inferred that the main roles of magnesium are to decrease the amount and rate of GP formation, to enhance the volume fraction of and to suppress the discontinuous precipitation of .This revised version was published online in November 2005 with corrections to the Cover Date.     

Some compounds of iron(III) with tertiary and secondary nitrogen bases

Summary The iron(III) compound, FeCl(OH)(MeCO₂) · MeCO₂ H · 0.5 H₂O, combines with tertiary nitrogen bases, pyridine, quinoline and-picoline, to form FeCl(OH)(MeCO₂) · (Base) 0.5 H₂O and with-picoline to give FeCl(OH)(MeCO₂) (-picoline). The secondary nitrogen bases (BH), such as, piperidine, pyrrolidine and diethylamine, on the other hand, react with the elimination of base hydrochloride to form Fe(B)(OH)(MeCO₂) · 0.5 H₂O compounds, containing covalently bonded bases. Pyrrole and indole (BH) combine with the partial elimination of chlorine to give Fe₃Cl₂(B)(OH)₃(MeCO₂)₃ · 3(BH). Phthalimide (BH), however, forms a simple addition compound Fe₂Cl₂(OH)₂(MeCO₂)₂ · (BH). The i.r. spectra, room temperature magnetic susceptibilities, thermal decompositions wherever possible and molar conductance have been studied.     

Kinetics and mechanism of the hydrolysis of sodium carboxymethylcellulose (Na-CMC) by a cellulase complex

TheSomogyi-Nelson colorimetric method is applied in a new manner more suitable for evaluating the kinetics of the enzyme hydrolysis of sodium carboxymethylcellulose (Na-CMC) catalyzed by the cellulase complex. By means of selective inhibition of a chosen enzyme from the cellulase complex it became possible to trace the effect of the other enzymes included in its composition.

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Kinetik und Mechanismus der Hydrolyse von Natriumcarboxymethylcellulose (Na-CMC) durch einen Cellulase-Komplex

Zusammenfassung Die kolorimetrische Methode nachSomogyi undNelson wird nach einem neuen Verfahren zur Verfolgung der Kinetik der hydrolytischen Spaltung von Natriumcarboxymethylcellulose (Na-CMC), katalysiert durch den Cellulase-Komplex, angewandt. Durch selektive Inhibierung eines bestimmten Enzyms des Cellulase-Komplexes kann man die Wirkung der anderen zu seiner gesamten Zusammensetzung gehörenden Enzyme verfolgen.

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Symbols Used E enzyme (E—cellulase;E—exo-cellobiohydrolase;E—-glucosidase) - [E] _w weight concentration of enzymeE - S substrate (Na-CMC—sodium carboxymethylcellulose) - [S]₀ weight concentration of substrateS - I inhibitor (I—lactose;I—calcium chloride;I—condurrite-B-epoxide) - P product (P—oligosaccharides;P—cellobiose;P—D-glucose) - P end product (K , K , K ) - DP degree of polymerization - DS degree of substitution - ES enzyme-substrate complex (E S, E S, E S) - EP enzyme-product complex (E P, E P) - EI enzyme-inhibitor complex (E I, E I, E I) - M _s molecular mass of substrateS - K _s substrate constant (K _s , K _s , K _s ) - K _I inhibitor constant (K _I , K _I , K _I ) - K _m Michaelis-Menten constant - k ₊₁,k ₊₂ (k ₊₂ ,k ₊₂ ,k ₊₂ ) forward rate constants - k _–1 reverse rate constant - ₀ initial rate of reaction - V maximal reaction rate - A change in absorbance - molar absorption coefficient - wavelength Herrn Prof. Dr.Hans Tuppy zum 60. Geburtstag herzlichst gewidmet.     

Synthesis and chemistry of dimetallacyclic compounds: Utility ofM(CO)4(η2-alkyne) (M=Ru,Os) building blocks

Low temperature photolysis ofM(CO)₅ (M=Ru, Os) provides efficient synthesis for a variety ofM(CO)₄(²-alkyne) derivatives. The molecules show surprising reactivity toward other 18-electron transition metal carbonyl compounds (M(CO)₅ and CpM(CO)₂,M=Co, Rh, Ir) to give homo- and heterodimetallacyclic complexes. The general features of the condensation reactions are described, the structures of the compounds discussed, and a few illustrative examples of the transformation of the bridging organic units given.     

A π-acceptor series for phosphines from51V N.M.R. data on [η5-CpV(CO)3L] complexes

Summary Qualitative molecular orbital considerations of the complexes [⁵-CPV(CO)₃ L] (L = substituted phosphane, SbPh₃, AsPh₃, CN^–) suggest that s' V chemical shift parameters () obtained for these compounds should correlate with the -acceptor abilities of L. Based on observed r-values, the ligands are arranged in sequence of their -acceptor ability, which lies in the order P(OR)₃ > CN^– > PR'₃3 SbPh₃ PPhF₂ > P(i-Bu)₃ P(NR ₂ )₃ > PPh₃ > AsPh₃ Nuclear spin-spin coupling constants J (⁵¹V-³¹ P), line widths H and i.r. data in the (CO) region are also presented.P(OR)₃ = P(OEt)₃, 4-Ethyl-l-phospha-2,6,7-trioxabicyclo[2.2.2]-octane; R = Me, n-Pr; R = Me, Et.     

Mixed-ligand and binuclear complexes of oxovanadium(IV)

Summary Mixed ligand complexes of the type [VOLA]ClO₄ where L=5-bromosalicylaldehyde (L) or 5-nitrosalicylaldehyde (L) and A=2, 2-dipyridyl (A) or 1, 10-phenanthroline (A) have been prepared. Treatment of the mononuclear complexes, [VOLA]ClO₄, withp-phenylenediamine (ppd) orm-phenylenediamine (mpd) yielded homobinuclear [VOLA-NC₆H₄N-LAVO](ClO₄)₂, complexes, which were characterised by elemental analyses, spectra, magnetic susceptibility and molar conductance measurements.     

Preparation and electrochemical study of manganese(II) macrocycles containing terpyridine

The macrocycle, L, prepared by template condensation of bis-6,6-(-methylhydrazino)-4-phenyl-2,2:6,2-terpyridine with glyoxal, forms a stable crystalline Mn^II complex, [Mn(L)(H₂O)₂][PF₆]₂, which has been used as a starting material for electrochemical studies on a series of seven coordinate Mn^II complexes [Mn(L)X₂]²⁺ (X = pyridine, 4-cyanopyridine, 4-aminopyridine, 4-dimethylaminopyridine, pyrazine, imidazole 1-methylimidazole, 2-dimethylimidazole or Ph₃P). Cyclic voltammetry of the complexes in MeCN shows a reversible one electron reduction wave in the range –1.32 to –1.42 V versus the Ag/AgBF₄ reference electrode.