2,3,4,5-Tetraethylpentela-cyclo-pentadienide (2,3,4,5-Tetraethylpentolide) der Erdalkalimetalle Magnesium, Calcium, Strontium und Barium

Abstract

Ad memoriam Egon WibergInhaltsu È bersicht. Die Umsetzung von Bis(cyclopentadienyl)-1-zirkona-2,3,4,5-tetraethyl-cyclo-penta-2,4-dien mit ECl 3 (E = P, As, Sb) ergibt in guten Ausbeuten 1-Chloro-tetraethylphosphol (1), -arsol (2) und -stibol (3). Die Reduktion dieser Pentole liefert zuna È chst das entsprechende Octaethyldiphospholyl (4), -diarsolyl (5) bzw. -distibolyl (6). Die weitere Reduktion dieser Dipentolyle mit Magnesium und Calcium fu È hrt in Anwesenheit der entsprechenden Erdalkalimetall-dihalogenide zu Magnesium-chlorid-(2,3,4,5-tetraethylphospholid) (7), -arsolid) (8) und -stibolid) (9) bzw. Calcium-chlorid-(2,3,4,5-tetraethylphospholid) (10), -arsolid) (11) und -stibolid) (12). In Abwesenheit von Erdalkalimetalldihalogeniden wird keine Reaktion beobachtet. Fu È r die gro È ûeren Metalle Strontium und Barium gelingt die Reduktion der Dipentolyle in THF auch ohne die Halogenide, wobei man dann die 1,1'-Dipentela-octaethylstrontocene [E = P (13), As (14), Sb (15)] und -barocene [E = P (16), As (17), Sb (18)] isoliert. Wa È hrend die Strontocene als THF-Addukte anfallen, kristallisieren die Barocene ohne neutrale Coliganden. Die Moleku È lstrukturen von 7, 10 und 16 werden mitgeteilt.2,3,4,5-Tetraethylpentela-cyclo-pentadienides (2,3,4,5-Tetraethylpentolides) of the Alkaline Earth Metals Magnesium, Calcium, Strontium, and Barium Abstract. The reaction of bis(cyclopentadienyl)-1-zircona-2,3,4,5-tetraethyl-cyclo-penta-2,4-diene with ECl 3 (E = P, As, Sb) yields 1-chloro-tetraethylphosphole (1), -arsole (2) und -stibole (3). The reduction of these pentoles gives in a first step the corresponding octaethyldiphospholyle (4), -diarsolyle (5) and -distibolyle (6). Further reduction of these dipentolyles with magnesium and calcium leads in the presence of the corresponding dihalides to the formation of magnesium chlorid (2,3,4,5-tetraethylphospholide) (7), -arsolide) (8) and -stibolide) (9) and calcium chlorid (2,3,4,5-tetraethylphospholide) (10), -arsolide) (11) and -stibolide) (12), respectively. In the absence of alkaline earth metal dihalides no reaction is observed. For the larger metals strontium and barium the reduction of the dipentolyles succeeds in THF also without the addition of halides and the 1,1'-dipentelaoctaethylstrontocene [E = P (13), As (14), Sb (15)] as well as -barocene [E = P (16), As (17), Sb (18)] are isolated halogen-free. The strontocene crystallizes as a THF adduct whereas the barocene precipitates coligand-free but with a chain structure. The molecular structures of 7, 10, and 16 are discussed.

Metalated Oligosilanylstibines

“…An attempt to accomplish the same reaction with magnesium as reducing agent did not lead to the distibine but rather to respective Grignard-type magnesium stibide 3 (Scheme ). Although magnesium stibides are a known class of compounds, the number of reported examples is still very small. − Compound 3 is not very stable, and over time in ethereal solution, it decomposes to the respective hydrostibine 4 . Freshly prepared 3 , however, is an interesting nucleophilic building block.…”

Synthesis and Spectroscopic and Structural Investigations of the 2,3,4,5-Tetraethylarsolides and -stibolides of the Alkali Metals Sodium, Potassium, Rubidium, and Cesium

“…After our investigations regarding the 2,2‘,3,3‘,4,4‘,5,5‘-octaethyl-1,1‘-diphosphaalkaline earth metallocenes we were interested in the synthesis, physical properties, and molecular structures of the 2,3,4,5-tetraethylarsolides and -stibolides of the heavy alkali metals sodium, potassium, rubidium, and cesium. A comparison of the tetraethylphospholides, -arsolides, and -stibolides of the alkali metals allows the determination of the influence of pnictogen and metal atoms with different radii and electronegativities on the molecular structures and the NMR spectroscopic parameters.…”

Synthesis and Crystal Structure of a Diphospholyl Magnesium(II) Chloride Complex

“…Although there are no previously reported examples of group 2 metal diphospholyl complexes, there has been one report of a magnesium phospholyl system, [{Mg(g 5 -PC 4 Et 4 )(THF)(l-Cl)} 2 ] [9], that is structurally very similar to 1. The Mg-P (2.6224(7) Å ) and Mg-C (mean: 2.484 Å ) distances in that compound are markedly shorter than those in 1, again most probably because of the lesser steric bulk of its phosphorus heterocycle.…”