Metal vapour synthesis of bis{1,3-bis(trimethylsilyl)cyclopentadienyl}-calcium, -strontium, and -barium compounds; X-ray structures of [M{η-C5H3-1,3-(SiMe3)2}2(thf)](M = Ca, Sr; thf = tetrahydrofuran)

Abstract

Cocondensation of C₅H₄(SiMe₃)₂, hexane, and metal vapour at –196 °C yields M{C₅H₃-1,3-(SiMe₃)₂}₂[M = Ca (1), Sr (2), and Ba (3)] which reversibly bind tetrahydrofuran (thf); X-ray structure determinations on the adducts [M{η-C₅H₃-1,3-(SiMe₃)₂}₂(thf)], [M = Ca (4) Sr, (5)] show they are monomeric bent metallocenes, M–C, M–O 2.662(10)–2.718(9), 2.310(9), (4), 2.78(4)–2.84(5), 2.49(3)Å, (5); Centroid–M–Centroid, 139.1, (4), 134°, (5).