Laszlo Zsolnai

Catalysis of allylic substitutions by Pd complexes of oxazolines containing an additional P, S, or Se Center. X-ray crystal structures and solution structures of chiral π-allyl palladium complexes of phosphinoaryloxazolines

Allylic alkylations with Pd complexes of chiral oxazolines with an additional donor P, S, or Se center are reported. Crystal and solution structures of palladium π-allyl complexes of phosphinoaryloxazolines were determined by X-ray crystallography and cross relaxation experiments, respectively. From the results conclusions concerning the steric course of allylic substitutions are drawn.

ansa-metallocene derivatives : XII. Diastereomeric derivatisation and enantiomer separation of ethylenebis(tetrahydronindenyl)-titanium and -zirconium dichlorides

Abstract Derivatisation of racemic ethylene-bridged bis(4,5,6,7tetrahydro-1-indenyl)-titanium and -zirconium dichlorides with O-acetyl- r -mandelic acid affords diastereomers which can be separately crystallised. Crystal and molecular structures of these diastereomers reveal different chelate ring conformations in the crystalline state. The separated diastereomers have been converted, via their dimethyl derivatives, into the corresponding titanocene and zirconocene dichloride enantiomers, the optical purity of these enantiomers has been demonstrated by their reconversion into the acetyl- r -mandelate derivatives.

Nackte hauptgruppenelemente als trigonal planar gebundene μ3-brückenliganden

Abstract In (LnM)2X-Hal compounds which contain a trigonally planar coordinated bridging element (X = P, As, Sb) stabilized by two 16-electron LnM fragments the halogen may be substituted by monovalent organometallic groups. In the resulting molecules the bridging X atoms are coordinated to three metal atoms in a trigonal planar fashion. The syntheses and properties of 12 species of this type (I–IX) are described. The reaction of Na2W2(CO)10 with XCl4 (X = Ge, Sn) leads to [(Co)5W]3(μ3-X) compounds containing trigonally planar coordinated Ge (X) and Sn (XI), respectively. The trigonal planar coordination of the Main Group elements X is confirmed by eight X-ray analyses.

Gezielte synthesen von zweifach μ3-verbrückten dreikernigen eisenclustern Fe3(CO)9(μ3-S)(μ3-X) (X = PR, AsR, SO) aus [Fe3(CO)9(μ3-S-t-C4H9)]−

Abstract The cluster anion [Fe 3 (CO) 9 (μ 3 -S-t-C 4 H 9 )] − , which is easily obtained by deprotonation from the cluster compound Fe 3 (CO) 9 (μ 2 -H)(μ 3 -S-t-C 4 H 9 ), reacts with XCl 2 by elimination of t-C 4 H 9 Cl and Cl − to give the clusters Fe 3 (CO) 9 (μ 3 -S)(μ 3 -X) (X = PR: I, X = AsR: II, X = SO: III), in which one edge of the iron triangle is opened. The μ 3 -PR-bridged clusters I can also be obtained by reactions of SCl 2 with the anions [Fe 3 (CO) 9 (μ 3 -PR)] 2− , prepared from Fe 3 (CO) 9 (μ 2 -H) 2 (μ 3 -PR) by deprotonation. The geometry of I and II is exemplified by X-ray structure analyses. Experimental evidence for a reaction pathway, proposed for the high yield syntheses of I, is discussed.

Syntheses and characterisation of [Os3(CO)11(PRH2)], [(μ2-H)Os3(CO)10(μ2-PRH)] (R = C6H5, p-CH3OC6H4, C6H11) and [(μ2-H)2Os3(CO)9(μ3-PR)] (R = C6H5, C6H11). Interconversion of cluster-bound phosphine and phosphido ligands. Crystal and molecular structures of [(μ2-H)Os3(CO)10(μ2-P(C6H5)H)] and [(μ2-H)2Os3(CO)9(μ3-PC6H5)]

Abstract Monoorganophosphines react with Os3(CO)12 in presence of trimethylamine oxide to give the phosphine-substituted cluster [Os3(CO)11(PRH2)] and the phosphido-bridged hydrido cluster [(μ2-H)Os3(CO)10(μ2-PRH)] (R = C6H5, p-CH3OC6H4, C6H11). The thermolysis of [Os3(CO)11(PRH)2)] gave, under different conditions, [(μ2-H)Os3(CO)10(μ2-PRH)] and [(μ2-H)2Os3(CO)9(μ3-PR)], and the thermolysis of [(μ2-H)Os3(CO)10(μ2-PRH)] gave [(μ2-H)2Os3(CO)9(μ3-PR)] (R = C6H5, C6H11). All the compounds have been studied by IR, NMR (31P and 1H) and mass spectrometry. The structures of [(μ2-H)Os3(CO)10(μ2-P(C6H5)H)] and [(μ2-H)2Os3(CO)9(μ3-PC6H5)] have been determined by X-ray crystallography. The results obtained for the system Os3(CO)12/PRH2 demonstrate a stepwise transformation of a terminally bonded PRH2 ligand to a doubly bridging μ2-PRH unit and finally to a triply bridging μ3-PR group by successive hydrogen transfer and CO substitution processes.

Dihalogenphosphankomplexe als metallorganische synthesebausteine

Abstract The dichlorophosphanes (R)P(Cl) 2 react with Fe 2 (CO) 9 to give (CO) 4 FeP(R)(Cl) 2 (I) in high yields. When treated with Fe 2 (CO) 9 in 2.5 M excess, compounds I give the μ 2 -chloro-μ 2 -chlorophosphido-bridged dinuclear molecules II, Fe 2 (CO) 6 (μ 2 Cl)(μ 2 -PRCl). Further treatment of II with Fe 2 (Co) 9 results in the formation of the trinuclear clusters IV, Fe 3 (CO) 10 (μ 3 -PR). Zinc reduction of II leads to V, Fe 4 (CO) 11 (μ 4 -PR) 2 . All of these reactions lead to fairly high yields for a variety of substituents R. The product selectivity is effectively controlled by the stoichiometry. The syntheses and properties of the main products I, II, IV and V, as well as those of the dinuclear side-products [(CO) 2 (Cl)(RPCl 2 )Fe(μ 2 -PRCl)] 2 (III), [(CO) 3 Fe(μ 2 -PRCl)] 2 (VI), and the trinuclear species (CO) 9 Fe 3 (μ 3 -PR) 2 (VII), are discussed.

Chirale tripodliganden : Die Eintopfreaktion MeC(CH2PPh2)3→MeC(CH2P(Ph)(R))3; Zwischenstufen, diastereoselektive Kontrolle und Komplexchemie

Abstract The tripod ligand H 3 CC(CH 2 PPh 2 ) 3 , 1 , reacts with lithium metal to produce H 3 CC(CH 2 PPhLi) 3 , 2 , in good yields. Compound 2 crystallizes in the form of 2 · 4 THF·MeN(CH 2 CH 2 NMe 2 ) 2 . The crystal structure of this adduct shows bridging as well as terminal phosphorous-coordination of lithium. Compound 2 reacts with electrophiles RX to give H 3 CC(CH 2 P(Ph)(R)) 3 , 3 (R = H, Me, Et, i Pr, CH 2 Ph, 3a–3e ). The transformation 1 → 2 → 3 can be performed in a one-pot reaction. While the chiral compounds 3 may be characterized as such, their reaction with (CH 3 CN) 3 Mo(CO) 3 yields the easy-to-characterize coordination compounds H 3 CC(CH 2 P(Ph)(R)) 3 Mo(CO)3, 5 . NMR analysis of 3 and 5 shows that from the two diastereomeric forms of 3 (the enantiomeric pair SSR / RRS and the pair SSS / RRR ) only the SSR / RRS -diastereomer is formed with R = CH 2 Ph ( 3e , 5e ). In the other cases (R = H, Me, Et, i Pr) a statistical 3:1 mixture of the two diastereomers is formed. These findings are further corroborated by X-ray analyses of H 3 CC(CH 2 P(Ph)(Et)) 3 Mo(CO) 3 , 5c , and H 3 CC(CH 2 P (Ph)(CH 2 Ph)) 3 Mo(CO) 3 , 5e . The remarkable facts reported in this paper are the ease with which the chiral tripod ligands H 3 CC(CH 2 P(Ph)(R)) 3 , 3 , are prepared, and the evidence that their formation may well involve diastereoselective control.

μ3-P- und μ3-As-verbrückte cluster als liganden

Abstract The trihalophosphane complexes LnMPHal3 (LnM = Cp(CO)2Mn, (CO)5Cr, (CO)5W; Hal = Cl, Br), upon treatment with Co2(CO)8, mainly yield clusters of the type Co3(CO)9(μ4-P)MLn with the (μ3-P)Co3(CO)9) unit acting as ligand. The analogous arsenic compound Co3(CO)9(μ4-As)Cr(CO)5 is obtained from the arsinidine complex [(CO)5Cr]2AsCl with NaCo(CO)4. In addition to the syntheses and reactios of these clusters several reactions leading to clusters with μ4-P-, μ4-As-, μ4-PR- and μ2-PR2 groups by reductive dehalogenation of coordinated halophosphanes are reported. The different types of compounds are documented by six X-ray-structure analyses.

Diphosphor, phosphor-, arsen- und antimonatome als clusterbaugruppen

Abstract Reactions of Fe2(CO)9 with LnMPHal3 (LnM = 16-electron fragment: Cp(CO)2Mn, (CO)5Cr, (CO)5Mo, (CO)5W) yield clusters of the type F3(CO)9(μ4-P)2(MLn)2 (II). Compounds II contain the trigonal bipyramidal cluster framework Fe3(CO)9(μ3-P)2, the basis of which is a closed triangle formed by three Fe(CO)3 units; the apical positions of the trigonal bipyramid are occupied by phosphorus atoms. Each of the capping phosphorus atoms binds an additional MLn fragment. Compounds of type II are also obtained from Fe2(CO)6(μ3-P)2(MLn)2 (I) by formal addition of an Fe(CO)3 group. A further general synthetic approach to clusters Fe3(CO)9(μ4-X)2 (MLn)2 (X = P, As, Sb) is the reaction of halo-phosphinidene, arsinidene or stibinidene complexes, (LnM)2XHal (X = P, As, Sb) with Na2Fe(CO)4. Similar procedures are used for the construction of compounds III and IV. Complexes III contain phosphorus as a μ4-spiro centre; compounds IV contain metallacyclic phosphanes (CO)4 FeP(R)Fe (CO)4 as ligands. From (CO)5CrPBr3 and Fe2(CO)9 the cluster Fe2(CO)7(PP)[Cr(CO)5]2 (V) is obtained in which a diphosphorus unit is side-on and end-on coordinated as an eight-electron ligand. The identity of the new compounds is documented by analytic and spectroscopic data as well as by X-ray-structure analyses of seven compounds.

ansa-metallocene derivatives : VIII. Syntheses and crystal structures of ethylene-bridged titanocene and zirconocene derivatives with permethylated ring ligands

Abstract Ethylene-bridged titanocene and zirconocene derivatives with permethylated ring ligands, C 2 H 4 (C 5 (CH 3 ) 4 ) 2 TiCl 2 and C 2 H 4 (C 5 (CH 3 ) 4 ) 2 ZrCl 2 , have been synthesized and their crystal structures determined.