Jörn Müller

Übergangsmetall-carben-komplexe XXVII. Ringsubstituierte (Methoxyphenylcarben)-pentacarbonylchrom(o)-komplexe

Abstract The preparation of a series of ring-substituted (methoxyphenylcarbene)-pentacarbonylchromium(O) complexes (CO) 5 CrC(OCH 3 )R (R= p -(CH 3 ) 2 NC 6 H 4 , p -CH 3 OC 6 H 4 , p -CH 3 C 6 H 4 , p -FC 6 H 4 , p -ClC 6 H 4 , p -BrC 6 H 4 , p -CF 3 C 6 H 4 , m -(CH 3 ) 2 NC 6 H 4 , m -CH 3 OC 6 H 4 , m -CIC 6 H 4 , m -CF 3 C 6 H 4 , o -CH 3 OC 6 H 4 , o -CF 3 C 6 H 4 , 2,4,6-(CH 3 ) 3 C 6 H 2 ,2,6-(CH 3 O) 2 C 6 H 3 ) and also (methoxyphenylcarbene)-, (methoxy-1-naphthylcarbene)-, and (methoxybenzylcarbene)pentacarbonylchromium(0) is described. The IR, 1 H NMR, and electronic spectra of these new compounds are discussed. The ionization potentials of several compounds are given. The σ-donor/π-acceptor behavioral of the different carbene ligands C(OCH 3 )R is investigated by means of the ν(Cue5f8O) absorptions, the CO force constants and the ionization potentials of the compounds. The rotational energy of activation about the C carbene ue5f8OCH 3 bond in the complexes is determined by temperature dependent 1 H NMR spectra. The variations in the bonding, which is caused by a single substituent in different positions on the phenyl ring, are discussed and compared with the values of their Jaffe σ-constants.

Massenspektroskopisher zerfall von pentacarbonylchrom- und tetracarbonyleisen-komplexen mit heterocyclischen carbenliganden

Abstract The electron impact induced fragmentation of Cr(CO) 5 and of Fe(CO) 4 complexes with heterocyclic carbene ligands derived from pyrazoline, imidazoline, triazoline, tetrazoline, thiazoline, and thiazolidine is described. The rather complicated degradation of the metal-carbene fragments formed by successive decarbonylation of the parent ions principally is the same for the iron and the chromium complexes and essentially depends on the structures of the carbene ligands. In some cases parallels between mass spectroscopic and chemical behaviour are observed.

Synthese und eigenschaften von cyclooctatetraencyclopentadienylchrom(I)

Abstract Paramagnetic C 5 H 5 CrC 8 H 8 was synthesized by the reaction of C 5 H 5 CrC 2 ·THF with C 8 H 8 in the presence of i-C 3 H 7 MgBr. The π-bonded eight-membered. ring contains a free double bond. From NMR data it appears that the ligand undergoes quick rotation. C 5 H 5 CrC 8 H 8 is protonated by HPF 6 to form the C 5 H 5 CrC 8 H 9 + ion. The cation is capable of adding nucleophiles to give derivatives of C 5 H 5 CrC 8 H 10 .

Über die synthese von π-sandwich-komplexen des vanadins mittels der isopropyl-grignard-methode

Abstract By the interaction of C 5 H 5 VCl 3 with i-C 3 H 7 MgBr in the presence of cyclic olefins, L, π-sandwich complexes of vanadium can be prepared. In the case of L = 1,3-cyclohexadiene, results a non-separable mixture containing V(C 5 H 5 ) 2 , V(C 6 H 6 ) 2 , and the new compound C 5 H 5 VC 6 H 6 . The raection with L = 1,3,5-cyclooctatriene yields a mixture of C 5 H 5 VC 8 H 10 and C 5 H 5 VC 8 H 9 which can be converted by catalytic dehydrogenation into pure cyclopentadienylcyclooctatrienylvanadium (0). With L = cycloheptatriene, C 5 H 5 VC 7 H 7 is obtained.

DI-π-azulen-komplexe des chroms und eisens

Zusammenfassung Wasserfreies CrCl 3 ergibt im System Azulen/iso-C 3 H 7 MgBr/O(C 2 H 5 ) 2 bei UV-Bestrahlung und nachfolgender Methanolyse polar gebautes, diamagnetisches, dunkelgrunes, sublimierbares π-Azulenium-chrom(o)-π-azuleniat, CrC 20 H 18 . Der Metalleinbau zwischen kationischem Siebenring und anionischem Funfring folgt aus IR- und PMR-Spektren sowie der Hydrierung zu blauem CrC 20 H 24 . Demgegenuber reagiert FeCl 3 unter denselben Bedingungen zu unpolarem, braunorangem, gleichfalls sublimierbarem, jedoch wesentlich oxydationsunempfindlicherem Di-π-azulen-eisen(o), FeC 20 H 16 . Die analoge Metallposition zwischen diesmal ungeladenen Ringliganden ergibt sich aus IR- und PMR-Spektrum und der Hydrierung zu gelbem FeC 20 H 26 .

Ringsubstituierte cycloheptatrienyl—vanadin-komplexe

Abstract Treatment of C 5 H 5 V(CO) 4 or V(CO) 6 with cycloheptatriene derivatives C 7 H 7 ue5f8X gives the π-bonded seven-membered ring substituted complexes C 5 H 5 VC 7 H 6 ue5f8X (X = CH 3 , C 6 H 5 , CN, CH 2 CO 2 R, OR, and CO 2 R) or (CO) 3 VC 7 H 6 ue5f8X (X = CH 3 , C 6 H 5 , OR, and CO 2 R). The course of the reactions is predominantly determined by the type and position of the substituents in the cycloheptatrienes. The mass spectra of the new compounds have been thoroughly investigated; numerous rearrangements occur in the decomposition of the molecular ions which is much more complicated than the breakdown of the free cycloheptatrienes. Finally the ionization potentials of the complexes measured by electron impact are given and discussed.

Massenspektroskopische unterscheidung geometrisch isomerer übergangsmetall-π-komplexe

Abstract The mass spectra and the fragmentation behavior are reported and interpreted for the geometrical isomers of cyclopentadiene-iron tricarbonyl complexes in which the 5-position of the π-bonded ring bears two different substituents. By considering one of the decomposition sequences emanating from the molecular ion, characterized by the radical scission of the exo substituent, it is possible to assign unequivocally the structure of a given compound without examining the spectrum of its geometrical isomer. The principle by means of which the distinction can be made is apparently generally applicable to all exo-endo isomeric pairs of transition metal π-complexes.