Stanislaw K. Tyrlik

EPR Studies of solvent coordination in bis(dimethylglyoxime)cobaltII complexes as catalysts for hydrogenation of nitrobenzene

Abstract EPR spectra of diaquocobaloxime and dimorpholine cobaloxime in different solvents have been studied in frozen solutions. It has been observed that magnetic parameters for solvent complexed cobaloximes depend strongly on the nature of the solvent, whereas morpholine-complexed cobaloxime shows no substantial variation of magnetic parameters with the solvents. The rates of nitrobenzene hydrogenation catalyzed by cobaloximes show considerable variation with solvent. It has been concluded that three elementary processes important for catalysis: hydrogen and nitrobenzene activation as well as hydrogen transfer, take place in the region of the active complex remote from the z axis.

Reactions of commercial ruthenium chlorides with O-donor ligands. Reactions with water: u.v.-vis. investigation of soluble products; analysis, thermogravimetry and an i.r. study of precipitated solids

SummaryThe u.v.-vis. absorption spectra of the products of reaction of commercial ruthenium chlorides with water have been measured. Deconvolution analysis revealed that hexaaquo-, pentaaquohydroxy- and pentaaquo-chlororuthenium(III) ions are formed, in addition to four unknown compounds.Analysis of the concentration data suggests the formation of soluble oligomers of the primary products over several hours following dissolution. Storage of the solution for ca. 170 h furnishes insoluble materials, characterized by analysis, thermogravimetry and i.r. The bulk of these solids can be described as [Ru2n + 2O3n + 3] ·mH2O or [Ru2n + 2O(3n + 3) - a(OH)2a·mH2O. We suggest the existence of ruthenium hydrides in these precipitated solids.

EPR STUDY OF THE SYSTEM [DIAQUOCOBALOXIME + AMINE] AS A CATALYST FOR THE HYDROGENATION OF NITROBENZENE

Abstract Reaction of cobalt dimethylglyoxime dihydrate with amines gives rise to a catalyst for hydrogenation of nitrobenzene. Solutions of this catalyst in acetone are paramagnetic and EPR spectra of these solutions were measured. The presence of nitrobenzene considerably alters the EPR spectra. It was also observed that electron transfer from cobaloximes to TCNE is only possible in the presence of PhNO2. Changes of the EPR spectra during catalytic process were observed and interpreted.

Electron spin resonance studies of the reaction product between hydridodinitrogentris(triphenylphosphine)cobalt(I) and olefins. I.

Abstract During the reaction of hybridodinitrogentris(triphenylphosphine)cobalt(I) with styrenes a paramagnetic cobalt complex is formed. The ESR spectrum of this complex is believed to contains 15 hf lines. On the grounds of the chemical reactivity of the compound and computer analysis of its ESR spectrum it is shown to be a binuclear cobalt complex. The influence of different Lewis bases, protic substances and cobalt oxidation reagents on ESR spectra is reported.

Searching for transition metal coordination compounds, which complex carbohydrates in water solution; synthesis, X-ray crystal structure and u.v.-vis. spectra of oxo-bis[bis-acetonitriletrichlororuthenium]

Coordination of alcohols and carbohydrate oxygen to a transition metal centre can result in many processes: formation of stable complexes via alcohol functionality (1); oxidfition of an alcohol, provided a metal complex is an oxidant (2), and oxidative addition of a R C H 2 0 H bond (3) to the metal. One can envisage, that oxidative addition of a R C H z O H bond will also begin with oxygen coordination producing a transient species. Ruthenium(IV) can be regarded as an interesting centre, being electrophilic but still possessing oxidizable electrons. We planned to identify such a species by oxidation of commercial ruthenium(III) chloride. In this communication we report preliminary observations concerning coordination of carbohydrates and alcohol to the newly synthesized Ru2OC16[NCMe] 4 (1) complex. Commercial ruthenium chloride [Aldrich: 35.6% Ru; 45.5% C1; 23.5% H 2 0 (0.13 g) in MeCN (15 cm 3) (spectral purity)] was boiled under reflux in air for 75 rain. The warm solution was filtered and the filtrate cooled to room temperature and then refrigerated ( 5 ~ Brown-black crystals precipitated after ca. 24h (yield 32-36%). The identity of this material was established by an X-ray study. Crystals subjected to structure determination had the following analysis (Found: C, 20.9; H, 2.7; N, 12.9; Ru2OC16[NCMe]g(MeCN)2 , C12Hx8Nz6C16ORu2 calcd: C, 21.3; H, 2.65; N, 12.4%). Some crops of crystals differed in composition from the formula RuzOC16[NCMe]4(MeCN)2 probably because of variable amounts of acetonitrile of crystallization. The i.r. spectra were taken in KBr and in Nujol mull. I.r. Vmax(Cm x): (2974, 2914) vs, (2326, 2298) vs, (1406, 1366) m, (1029, 954) m, 486 s, 407 w. XH-n.m.r. (200 MHz, D20 ) 2.05 s, 2.21 s ten times weaker than 2.05. Figure 1 shows the molecular structure of (1). Crystal data for (I): C12H18N6C16ORuz.M = 653.15, monoclinic, space group C2/m, a = 14.688(4), b = 10.448(3), 3 c = 8.241(2) ~; fl = 96.84(1), v= 1255.67~, F(000)= 879, Z = 2, D c = 1.727523 gcm3 total number of reflections 1776, R(F)=0.0235 and Rw(F)=0.025, wavelength =0.71069/~. A crystal ca. 0.25 x 0.25 • was mounted on a glass fibre and transferred to a goniostat. The data collection was made at -173 ~ using the standard moving crystal, moving detector technique with fixed background counts at each extreme of the scan. Data were corrected for Lorentz and polarization terms and

Reactions of tetralin induced by metal salts and complexes: Part I. Selectivity in tetralin reactions catalyzed by modified AlCl3

Abstract Reaction of tetralin in the presence of AlCl 3 and its modifications has been reinvestigated and the products identified. 5- and 6-(1-phenylbutyl) tetralins are the primary products, which subsequently form partly hydrogenated tricyclic aromatic compounds and benzene. Further reactions produce ethylbenzene, n-butylbenzene, ethyltetralins and n-butyltetralins. A catalytic system containing AlCl 3 and hydrated salts (CH 3 COONa·3H 2 O and FeCl 3 ·2H 2 O) has been found to convert tetralin to 5- and 6-(1-phenylbutyl)tetralins with high selectivity.

Crystal structure oftrans-(benzyl-C)bis(dimethylglyoximato-N,N′)-(morpholine-N)cobalt(III)-monohydrate

SummaryThe title compound crystallizes in the monoclinic space group P21/n, with cell dimensions:a = 8.535(4) Å,b = 13.009(4) Å,c = 20.615(5) Å, β = 100.57(3)∘ and Z = 4. The central cobalt atom coordination is a slightly distorted octahedron, formed by five N-atoms (two glyoximes and morpholine) and one C-atom.The interaction between the complex Co-units is weak: the strongest nearest neighbour interaction is formed by a hydrogen bridge in which the water molecule of crystallization acts as the donor part.

EPR spectra of products of the reaction of di-η5-cyclopentadienyl(diethylalanedi-μ-chloro)titanium(III) with C1 compounds

Abstract The outcome of the reaction of di-η5-cyclopentadienyl(diethylalanedi-μ-chloro)titanium(III) (IA )with MeOH depends strongly on the molar ratio: with IA/CH3OH

E.s.r. spectra of radicals formed in the system formaldehyde–diaquacobaloxime–nitroso-compound; methylene or oxymethylene trapping

Diaquacobaloxime promotes formation of radicals from formaldehyde; products of trapping of these radicals by nitroso-compounds have unusually small methylene hyperfine coupling constants.

A chemical study of a black slurry formed from CoAcAc3 + iBu3Al in the presence of pr3 at the molar ratio Co:PR3 = 1:1 and remarks on its catalytic activity

Abstract The reactivity of the product of reaction (CoAcAc3 + iBu3Al + PPh3), symbolized as I, was studied for the molar ratio Co:P  1:1. The hydrogenating activity of I with respect to PhCh2Br, (CH3)2CO, HgPh2, PbPh4 and SnOct4 was higher than that of Zieglers mixtures (CoAcAc3 + iBu3Al) prepared without PPh3. In system I reduction of triphenylphosphine to benzene was observed. Lower aggregative properties and lower catalytic activity of system I by comparision with the system (CoAcAc3 + iBu3Al) was observed.