Synthesis and spectroscopic properties of cyclopentadienyl(methyl)beryllium and cyclopentadienylberyllium halide complexes

Abstract

Dicyclopentadienylberyllium reacts with dimethylberyllium or beryllium halides in the absence of solvent to form mixed C5H5BeX complexes. The products are stable toward disproportionation and monomeric in solution and vapor phases. NMR, IR, and mass spectral data are presented. The bonding interaction between beryllium and the cyclopentadienyl ring is discussed.The preparation and characterization of mixed alkyl (RMR') and alkylmetal halides of the group 2 metals have received much attention in the literature. Redistribution reactions between dialkyl and diaryl compounds of mercury2,3 and magnesium4 have been investigated. The mercury alkyls

Shape and Symmetry of Heptacoordinate Transition‐Metal Complexes: Structural Trends

“…4) Among the multidentate ligands analyzed, the extended tripod pytren seems to favor the CO geometry, whereas tridentate ligands such as triazacyclononane and tris(pyrazolyl)borate show a diversity of coordination polyhedra. The pentadentate crown ethers such as [15]crown-5 clearly favor the PBP geometry. The [18]crown-6 and related crown ethers, on the other hand, favor the hexagonal pyramid for the alkaline-metal ions as well as for the only transition-metal complex found with such a type of ligand.…”

“…[32] In addition, we observe that a bond angles (72 ± 778) in homoleptic complexes are systematically larger than the corresponding values in the octahedron (54.78), whereas the b angles (117 ± 1378) can be smaller or larger than in the octahedron (125.38), while the minimum interligand repulsion is found at 73.3 a 75.88 and 128.8 b 131.48 according to point charges calculations, [36] or 70 a 848 and 127 b 1388 from molecular orbital calculations. [22] Considering all these data, the criterion of ideality for the CO adopted by Drew (a 74.18, b 125.58) [15] seems a reasonable one. Those values were found in the structure of the [W(CO) 4 Br 3 ] À ion, [37] which has crystallographically imposed C 3v symmetry.…”

“…The complexes with the pentadentate [15]crown-5 ether are practically all PBP (data provided as Supporting Information), with the crown ether occupying the equatorial plane of the bipyramid. The only exception is a Cd complex [59] with a structure that is nearly isosymmetric relative to the three ideal polyhedra.…”

“…Drew reported a least-squares procedure to assign the stereochemistry of heptacoordinate complexes, [15] and a similar approach has been more recently proposed by Maseras and Eisenstein, [28] but the assignment of a coordination polyhedron is still in most cases done in a non systematic way. A related approach applied by Allen and coworkers to the study of the shape of heptacoordinate complexes consists in analyzing the n(n À 1)/2 bond angles of an ML n core and use of a Euclidean dissimilarity metric as a one-dimensional comparator of those angles.…”

Über die Reaktivität von [(CH3)2N]6W2 (W≡W) gegenüber CS2/S8 und CS2/Se8. Röntgenstrukturanalyse von [(CH3)2NCS2]2W(S)(S2) / Reactivity of [(CH3)2N]6W2 (W≡W) Towards CS2/S8 and CS2/Se8. X-Ray Structure Analysis of [(CH3)2NCS2]2W(S)(SZiegler1, Blechschmitt2, Böck3 et al. 1988Zeitschrift Für Naturforschung B7010View full textAdd to dashboardCite

“…L 3 gliedert sich auf in einen Sulfido-und einen Disulfido-Liganden (B'-B'), so daß sich die allgemeine Form ML(B-B) 2 (B'-B') ergibt. 4 gehört zu den seltenen, bei der Wolframchemie jedoch wegen den zur Edelgaskonfiguration des Radon fehlenden 14 Elektronen (W(II)) nicht ungewöhnlichen siebenfach koordinierten Verbindungen [13]. Vom Wolfram und Molybdän sind analoge Strukturen bereits bekannt, wie z.B.…”