Synthese und Eigenschaften von substituierten Bis(cyclopentadienyl)calcium‐Verbindungen; Kristallstruktur von monomerem Bis[1,3‐bis(trimethylsilyl)‐cyclopentadienyl](tetrahydrofuran)calcium

Abstract

Einige Addukte des Bis(cyclopentadieny1)calciums rnit Lewis-Basen sind zwar beschrieben'**), jedoch liegen keine Kristallstrukturuntersuchungen vor.Erst kiirzlich ist iiber die Synthese des Bis(pentamethy1-cyclopentadieny1)calciums berichtet worden9). Elektronenbeugungsuntersuchungen in der Gasphase sprechen interessanterweise fur das Vorliegen von Monomeren mit gewinkelt angeordneten, pentahapto-gebundenen Cyclopentadienyhngen. Bis(pentamethylcyclopentadieny1)calcium konnte bisher nicht in kristalliner Form erhalten werden. Es fallt rontgenamorph an, was sich auch mit unseren Erfahrungen deckt.

Formation and Crystal Structure of a Cationic Mono(cyclopentadienyl) Complex of Calcium, [(C5Me5)Ca(OPPh3)3]+I-

“…The average Ca-C distance of 2.684(4) Å is longer than that usually observed in neutral complexes with a formally six-coordinate Ca 2+ center (cf. 2.63(2) Å in [C 5 (t-Bu) 3 H 2 ]CaI(thf) 2 20 ) and is similar to that found in seven-coordinate species (e.g., 2.678(9) Å in [1,3-(SiMe 3 ) 2 C 5 H 3 ] 2 Ca(thf) 21,22 and 2.67(1) Å in [(C 5 Me 5 )-Ca(µ-I)(thf) 2 ] 2 8 ). The Ca-O distances range from 2.254-(2) to 2.300(2) Å, and the Ca-O-P angles are bent from 150.99(9) to 166.4(1)°.…”

Synthesis and stabilization—advances in organoalkaline earth metal chemistry

“…Highly acidic ligands react under reflux conditions. 61,62 Less acidic ligands benefit from metal activation, as achieved by the presence of anhydrous ammonia (gaseous [63][64][65] or liquid [65][66][67][68][69] ). Furthermore, co-condensation methods have provided limited access to synthetically challenging targets as well.…”

Synthesis and Crystallographic Study of Indenyl and Isopropylated Indenyl Complexes of Calcium, Strontium, and Barium

“…The average Ca−C distance of 2.69(2) Å is as expected for a 7-coordinate calcium center (cf. 2.678(8) Å for the Ca−C distance in {C 5 H 3 -1,3-(SiMe 3 ) 2 } 2 Ca(thf) and 2.67(1) Å in [(Me 5 C 5 )CaI(thf) 2 ] 2 ). The Ca−O(thf) distance of 2.323(5) Å is comparable to the 2.329(3) Å distance observed in {C 5 H 3 -1,3-(SiMe 3 ) 2 } 2 Ca(thf), but is somewhat shorter than the average Ca−O(thf) distance observed in [(Me 5 C 5 )CaI(thf) 2 ] 2 (2.40(2) Å), which may reflect greater steric crowding in the latter.…”