Axel Herzog

Synthesis and structures of paramagnetic organo titanium fluoride clusters

Abstract The organo titanium(IV)trifluoride [C 5 H 4 (SiMe 3 )]TiF 3 , 2 , has been reduced with zinc and manganese, respectively. As an intermediate product from these reactions the tetra-nuclear Ti III cluster {[C 5 H 4 (SiMe 3 )] 2 TiF 2 } 3 Ti, 3 , has been obtained. By oxidative fluorination using AgF complex 3 was converted to the titanium(IV) complex [C 5 H 4 (SiMe 3 )] 2 TiF 2 . Reduction of (C 5 H 5 ) 2 TiF 2 with gallium led to the formation of [(C 5 H 5 ) 2 TiF 2 ] 3 Ga, 7 .

2,4,6-Trimethylpyridine–bishydrofluoride: a novel fluorinating reagent for organo transition-metal alkyls

Complexes [M(η5-C5Me5)F3](M = Zr 2, Hf 5), [Zr(η5-C5H5)F2] 7 and [Hf(η5-C5Me5)F2] 8 are obtained by treating the corresponding metal alkyls with [tmpy-(HF)2](tmpy = 2,4,6-trimethylpyridine); using an excess of [tmpy-(HF)2] in the preparation of 2 and 5 leads to the complexes [Htmpy][{M(η5-C5Me5)F2}(µ-F)3](M = Zr 3, Hf 6), respectively and a crystal structure determination of 3 confirms its ionic nature; [Ti(η5-C5Me5)Cl2F] 10 and 2 were synthesised also from their corresponding alkyls by alkyl–fluorine exchange using Me3SnF.

The Activation of Metal-Fluorine Bonds in Compounds of Group 4 by Aluminum Alkyls

In recent years we have developed the facile preparation of group 47#x2013;6 and main-group fluorides from the corresponding chlorides using Me3SnF as a fluorinating reagent. Reactions of group 4 organometallic fluorides with alkyls of group 13 elements, especially those of aluminum, are of particular interest with regard to the mechanism of homogeneous catalysis for the polymerization of olefins. The formation of adducts of group 4 metallocene halides with AlMe3 is assumed to be the first step of activation of a polymerization catalyst when AlMe3 containing methylaluminoxane (MAO) is used. The following methylation of the metallocene centers is markedly facilitated by this electrophilic support. In order to understand the catalytic activity of those compounds, it is neccessary to examine whether a selective coordination of the fluorine atoms and an exchange for alkyl and amino groups, respectively, is possible using aluminum compounds.

Synthesen und Strukturen sechsgliedriger Cyclometallaphosphazene von Tellur(IV) und Rhenium(VII) / Syntheses and Structures of Six-Membered Cyclometallaphosphazenes Containing Tellurium(IV) and Rhenium(VII)

The reactions of the tridentate ligands (Me3Si)2NC(4-RC6H4)NPPh,NSiMe3 [(1): R=H, (2): R=CF3] with Re2O7 yield the six-membered rings , (4): R=CF3]. The acyclic compound Me3SiNC(4-CF3C6H4)NPPh2NReO2OSiMe3 (5) has been obtained by reaction of 2 with Me3SiOReO3- 2 reacts quantitatively with TeCl4 to form the metallacycle . The molecular structures of 4·CH2Cl2 and 6 · pyridine · 0.5 toluene have been determined by X-ray diffraction.