TY  - JOUR
A1  - Ries, Wolfgang
A1  - Albright, Thomas
A1  - Silvestre, Jerome
A1  - Bernal, Ivan
A1  - Malisch, Wolfgang
A1  - Burschka, Christian
T1  - Unusual structural features of a siloxane
N2  - Crystals of the R, S diastereoisomer of [Cp(CO)\(_2\)-FeSiCH\(_3\)F]\(_2\)O are monoclinic, space group ndc (No. 14), with a = 846.0(3) [836.4(1»), b = 768.0(3) [757.1(1»), c = 1548.5(4) [1522.3(2)] pm, {3 = 97.34(3t [97.47(3t] at 300 K [120 K] with Z = 2. Even at 120 K the Si-O-Si fragment is found to be strictly linear due to crystallographically imposed symmetry. To explain the unusual electron distribution derived from the X-ray data collected, several types of possible disorders are discussed, none of which leads to a satisfying explanation. Retaining the Ci symmetry (linear Si-O-Si fragment in the final model) the important bond lengths are Fe-Si 226.7(1) [226.5(1)] pm, Si-F 160.9(2) [161.8(2)] pm, Si-O 160.3(1) [161.1(1)] pm, Si-C 185.0(3) [185.6(3)] pm. The electronic features of this compound were probed via molecular orbital calculations of the extended Hiickel type. It was found that the lone pairs on the siloxane oxygen were tipped away from cylindrical symmetry. The tipping was directed toward the fluorine substituents on the silicon atoms and away from the CpFe(CO)\(_2\) units. A pertubational approach was utilized to rationalize this effect.
KW  - Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31925
ER  - 
TY  - JOUR
A1  - Groß, Elisabeth
A1  - Burschka, Christian
A1  - Malisch, Wolfgang
T1  - Hauptgruppenelement-Übergangsmetall-Mehrfachbindungen, IV. Katalytische Assistenz von [Cp(C0)\(_3\)Mo]\(_2\) bei der Aggregation von Metallo-arsanen über Arsen-Metall-Doppelbindungskomplexe
T1  - Main Group Element Transition Metal Multiple Bonds, IV. Catalytic Assistance by [Cp(CO)\(_3\)Mo]\(_2\) in the Aggregation of Metalloarsines via Arsenic Metal Double Bond Complexes
N2  - The metallo-arsanes CP(CO)\(_3\)M - AsMc\(_2\) (1 a, b) (M = Mo, W) are convcrted to the double arsenido-bridged dinuclear complexes [(η-AsMe\(_2\))Mo(CO)\(_2\)Cp]\(_2\) (3a, b) in the presence of [CP(CO)\(_3\)Mo]\(_2\). Due to the unusual mild conditions of aggregation the intermediate formation of the double bonded species Cp(CO)\(_2\)M = AsMe\(_2\) (2a, b) is postulated. The crystal structure of 3a is reported, which shows mutual trans arrangement of the cyclopentadienyl and CO ligands.
KW  - Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31424
ER  -