ISSN:
0009-2940
Keywords:
Germanium(II) complexes
;
Electron pair, „inert“
;
Spiro compounds
;
Molecular fluctionality
;
Phosphanylmethanide ligands
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Ring Expansion of Spirocyclic Germanium(II) Di(phosphanyl)methanide Complexes by Insertion of Sulfur and Selenium into Germanium-Phosphorus BondsGermanium in the intermolecularly stabilized germylene derivative Ge[C(PMe2)2(SiMe3)]2 (2a) is not oxidized by sulfur but the latter inserts 1 to 4 chalcogenide atoms into the Ge-P bonds of the four-membered chelate (4/4-) rings to give 4/5-, 5/5-, 5/6, and 6/6-membered spirocycles Ge[C2(SPMe2)n(PMe2)4-n(SiMe3)2] (n = 1-4: 4, 5a, 6, 7). Only 5a and 7 could be obtained in pure form, whereas compounds 4 and 6 with odd-numbered chalcogenide atoms are only characterized in solution, where they exist in equilibrium with 2a and 5a or 5a and 7, respectively. All these molecules are fluctional in solution. 7 is also obtained from GeCl2 · dioxane and Li[C(SPMe2)2(SiMe3)]. The selenium compound Ge[C(SePMe2)(PMe2)(SiMe3)]2 (5b) is obtained from 2a and grey selenium in toluene. An X-ray structure determination of 5b shows a distorted sphenoidal arrangement [approximate C2 symmetry of a spirocyclic germanium center within two five-membered rings containing a nearly linear Se-Ge-Se unit (Ge-Se 2.712/2.769(1) Å)]. The angle PGeP is 95.9(1)°. A bonding model with a stereochemically non-active electron lone pair at the formal germanium(II) center may account for this geometry. As byproducts in the sulfurization reactions, bis-(phosphanyl)methane disulfides are also observed in certain cases, from which H2C(SPMe2)2 has been isolated in pure form and characterized structurally.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19921250606
Permalink
