Hans-Ulrich Hund

ansa-Metallocene derivatives: XVI. Chiral titanocene and zirconocene derivatives with symmetrically substituted, tetramethylethanediyl-bridged ligand frameworks. Crystal structures of representative examples

Syntheses of disubstituted, tetramethylethanediyl-bridged titanocene derivatives (CH3)4C2(1-C5H3-3-R)2TiCl2, with R  t-butyl, trimethylsilyl, isopropyl, α,α-dimethylbenzyl and 1-phenylcyclohexyl, by reductive coupling of the appropriately substituted 6,6-dimethylpentafulvenes with Mg/CCl4 and reaction of the resulting di-Grignard compounds with TiCl3·3THF are described along with those of several zirconium analogues. The reaction sequence in each case gives, together with the desired racemate, comparable amounts of the corresponding meso-configurated complex. The NMR data for the racemic and meso diastereomers of these compounds and crystal structures of one meso and several racemic representatives are reported.

Koordination und Chemie von Acetylenen an dicarbonylbis(tirmethlphosphit)eisen-fragmenten

Abstract The μ-dinitrogenbis[dicarbonylbis(trimethylphosphite)iron] complex ( 1 ) reacts with acetylenes R 1 CR 2 (R 1 , R 2 = H, Ph) to yield the acetylene substitution products, (OC) 2 [P(OMe) 3 ] 2 Fe(R 1 CCR 2 ) (R 1 , R 2 = Ph 2a ; R 1 = H, R 2 = Ph, 2b ; R 1 = R 2 = H, 2c ) under elimination of N 2 . 2b and 2c undergo reversible insertion into the acetylenic CH bond to yield the acetylide hydrido species (R 2 = Ph, 3b ; R 2 = H, 3c ). The reaction of 1 with methyl propiolate leads to a carbonyl-2,3,6-tris(methylcarbonyl) hexa-1,3,5-triene-diyl-bis(trimethylphosphite)iron compound ( 5 , which has been characterized by an X-ray diffraction study.

Trimerisierung von Propiolsäuremethylester an Dicarbonylbis(phosphordonor)eisen-Komplexen

Abstract The dinitrogen complex (CO) 2 L 2 FeNNFeL 2 (CO) 2 (L  P(OMe) 3 ( 1a ), P(OMe) 3 ( 1a ), P(O i Pr) 3 ( 1b ), PEt 3 ( 1c )) reacts with methyl propiolate under elimination of N 2 to yield the corresponding acetylene substitution products [(CO) 2 L 2 Fe(η 2 -HCCCOOMe)] ( 2 ) and the prototropic vinylidine complexes [(CO) 2 L 2 FeCC(H)COOMe)] ( 3 ). In a subsequent reaction 2,3 inserts two equivalents of methyl propiolate and results in the formation of carbonyl-2,4,6-tris(methoxycarbonyl)hexa-1,3,5-triene-1,5-diyl-bis(phosphorus-donor)iron compounds ( 4,5a ) and a carbonyl-1,3,6-tris(methoxycarbonyl)fulvenebis(triisopropylphosphite)iron complex ( 6 ). The complexes 5a,6 were determined by X-ray diffraction analyses.

Reaktionen von Propiolaldehyd-derivaten mit dicarbonylbis(trimethylphosphit)eisen-fragmenten

Abstract The reaction of a μ-dinitrogenbis(dicarbonylbis(trimethylphosphite)(iron) complex ( 1 ) with halogenopropinal acetals yields acetylidodicarbonylhalogenobis(trimethylphosphite)iron compounds, (OC) 2 [P(OMe) 3 ] 2 Fe(X)CCCH(OR) 2 , X = Cl, 6 ; X = Br, 7 ; X == I, 8 ; R = Me, a ; R = Et, b ; (OR) 2 O(CH 2 ) 3 O, c ). 1 and propinal acetals react with formation of a dicarbonylbis(trimethylphosphite)carbaldehydevinylidene)iron complex ( 9 ). a {(OC) 2 [P(OMe 2 ] 2 FeCCHC(H)O(CH 2 ) 3 O} 2 species ( 10 ) is generated in low yield when 1 is treated with 2-(1-chloroethinyl)-1,3-dioxane ( 3 ). 8a, 9 and 10 were characterized by X-ray analyses.

η2-Coordination in pentacoordinate iron complexes

Abstract The reactions of the dinitrogen complexes μ-N 2 [Fe(CO) 2 L 2 ] 2 (L = P(OMe) 3 , 1a ; P(O-i-Pr) 3 , 1b ; PEt 3 , 1c ) with diphenylketene diphenyl- p -tolylketene imine and propionitrile give the η 2 -C,O ketene compounds Fe(CO) 2 L 2 Ph 2 C 2 O (L = P(OMe) 3 , 2a ; P(O-i-Pr) 3 , 2b ; PEt 3 , 2c ) a ketene imine system Fe(CO) 2 [P(OMe) 3 ] 2 Ph 2 C 2 N-p-tolyl ( 3 ) and the propionitrile substitution derivatives Fe(CO) 2 L 2 EtCN (L = P(OMe) 3 , 4 ; PEt 3 , 5 ), respectively. The structures of 2c, 3 and 5a have been determined by X-ray diffraction.

ansa-Metallocene derivatives XVIII. Chiral titanocene derivatives accessible from substituted dihydropentalene and azulene precursors☆

The product of an Mg/CCl4-induced reductive coupling of guaiazulene reacts with TiCl3·3THF to yield, after oxidation with HCl/O2, R,S-8,8′-biguaiazulenide titanium dichloride, which contains a CC bond between its two guaiazulenide ligand moieties. A similar reaction sequence starting from 3-phenyl-1,2-dihydropentalene gives unbridged R,S-bis(4-exo-phenyl-4H-5,6-dihydropentalenide)titanium dichloride.

1,2-Halogenverschiebung in cymantrenacetylen-komplexen

Abstract The photochemical CO substitution in CpMn(CO) 3 by 1-halogenopropinal acetals, XCCCH(OR) 2 , yields the complexes CpMn(CO) 2 -η 2 -(XCCCH(OR) 2 ) (X = Cl ( 5 ); X = Br ( 6 ); X = I ( 7 ); R = Me ( a ; R = Et ( b ; (OR) 2 O(CH 2 ) 3 O( c )). The compounds 7 rearrange to give the corresponding iodovinylidene derivatives CpMn(CO) 2 CC(I)CH(OR) 2 ( 8 ). 8a has been characterized by an X-ray diffraction study.

Reaktionen von Propiolaldehydacetalen mit Dicarbonylcyclopentadienylmangan-Fragmenten

Abstract Reactions of a dicarbonylcyclopentadienylethermanganese complex ( 1 ) with propiolic aldehyde acetals ( 2 ) yield the mononuclear dicarbonylcyclopentadienyl-η 2 -(propiolic aldehyde acetal)manganese compounds CpMn(CO) 2 HCCCH(OR) 2 (R  Me, 3a ; R  Et, 3b ; (OR) 2 O(CH 2 ) 3 O, 3c ). In addition dinuclear bis(dicarbonylcyclopentadienyl)dialkoxymethylvinylidene complexes [CpMn(CO) 2 ] 2 CC(H)CH(OR) 2 (R  Me, 5a ; R  Et, 5b and (OR) 2 O(CH 2 ) 3 O, 5c ) and a bis(dicarbonylcyclopentadienylmanganese)-2-carbaldehydevinylidene species ( 5d ) have been isolated. These dinuclear compounds were also obtained via dicarbonylcyclopentadienyl(dialkoxymethylvinylidene)manganese derivatives CpMn(CO) 2 CC(H)CH-(OR) 2 (R  Me, 4a ; R  Et, 4b ; (OR) 2 O(CH 2 ) 3 O, 4c ), which were synthesized by an independent route. 3c , 5c and 5d were characterized by X-ray analyses diffraction studies.

New heterodimetallic cyclopentadienyl carbonyl complexes: crystal structure of (C5Me4Et)(μ-CO)3Ru(C5Me5)

Abstract A series of heterodimetallic complexes of general formula (C5R5)M(μ-CO)3RuC5Me5 (M  Cr, Mo, W; R  Me, Et) has been prepared in good yields by the reaction of [C5R5M(CO)3]− with [C5Me5Ru(CH3CN)3]+. (C5Me4Et)W(μ-CO)3Ru(C5Me5) was characterized by a crystal structure determination. The WRu bond length of 2.41 A is consistent with the formulation of a metal-metal triple bond, while the unsymmetrical bonding mode of the three bridging carbonyl groups reflects the inherent non-equivalence of the two different C5R5M-units. Using [CpRu(CH3CN)3]+ or [CpRu(CO)2(CH3CN)]+ as the cationic precursor leads to the formation of dimetallic species (C5R5)M(CO)5RuC5H5 with both bridging and terminal carbonyl groups.