Bis(tert-butylcyclopentadienyl)magnesium, -calcium, -strontium, and -barium Metallocenes

Michael G. Gardiner, Colin L. Raston, Colin H.L. Kennard

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Bis(tert-butylcyclopentadienyl)metal derivatives, M(t-BuC5H4)2, M = Mg, Ca, Sr, and Ba, have been prepared by metalation using Mg(s-Bu)(n-Bu) or metal vapors for the heavier group 2 elements. The Ca, Sr, and Ba compounds are only sparingly soluble in hydrocarbon solvents and have been characterized by using 13C CP/MAS NMR spectroscopy with TOSS pulse sequences. Addition of THF (tetrahydrofuran) to these compounds yields THF adducts that have been isolated as [M(t-BuC5H4)2(THF)2] for Ca and Sr. Both have been structurally characterized, along with [Mg(t-BuC5H4)2]. The latter is a regular metallocene: Mg-centroid = 2.00 Å, centroid-Mg-centroid = 180°; crystals are monoclinic, space group P21/n, a = 6.270 (4) Å, b = 11.213 (3) Å, c = 11.932 (7) Å, β = 96.53°, V = 833.6 Å3, Z = 2. The THF adducts are isostructural and are monomeric bent metallocenes, with four coordinate metal centers, assuming the cyclopentadienyl ligands to be unidentate: Ca, Sr-centroid = 2.46, 2.61 Å, Ca,Sr-O = 2.40, 2.53 Å, centroid-M-centroid = 133.3,133.1°, O-M-0 = 83.2 (2), 83.1 (2)°; crystals are monoclinic, space group P21/n, a = 13.527 (4), 13.793 (3) Å, b = 10.057 (4), 10.308 (1) Å, c = 20.254 (7), 20.269 (5) Å, β = 106.24 (1), 107.66 (1)°, V = 2445 (1), 2746 (1) Å3, Z = 4 (Ca, Sr values, respectively).

Original languageEnglish
Pages (from-to)3680-3686
Number of pages7
JournalOrganometallics
Volume10
Issue number10
DOIs
Publication statusPublished - 1 Oct 1991
Externally publishedYes

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