- Organochromium π-complexes. 3. Preparation and reactions of bis(η3-allyl)chromium(II) complexes
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Cr(PR3)2Cl2 (PR3 = PMe3, PMe2Ph, PPh2Me), Cr(Me2PC2H4PMe2)2Cl 2, and [Cr(Pri2PC2H4PPri 2)Cl2]2 react with 2-propenylmagnesium chloride or 2-methyl-2-propenylmagnesium chloride to give thermolabile (η3-allyl)2Cr(PR3)2 and (η3-allyl)2Cr(R2PC2H 4PR2) compounds. In contrast, the final product of the reaction between Cr(PMe3)2Cl2 and 2-butenylmagnesium chloride contains an η2,η2-bonded dimethyldiallyl group derived from the reductive coupling of two η3-1-MeC3H4 fragments. (η3-C3H5)2Cr(PMe 3)2 reacts with 2-butyne with alkyne insertion into an η3-allyl group to give a compound containing both η3-allyl and η1,η2-4-methyl-1,4-hexadienyl groups. The structures of these paramagnetic organochromium(II) compounds have been confirmed by X-ray structural determinations of three examples, viz. (η3-C3H5)2Cr(PMe 2Ph)2 (2) (a = 8.894 (4) A?, b = 27.56 (1) A?, c = 9.355 (3) A?, β = 107.64 (3)°, space group P21/n, Z = 4), (η3-C3H5)2Cr(Pri 2PC2H4PPri2) (6) (a = 9.171 (1) A?, b = 15.936 (2) A?, c = 15.368 (1) A?, β = 102.22 (1)°, space group P21/n, Z = 4) and (η3-C3H5)(η1,η 2-4-methyl-1,4-hexadienyl)Cr(PMe3)2 (9) (a = 9.299 (5) A?, b = 14.474 (8) A?, c = 13.916 (5) A?, space group P212121, Z = 4).
- Betz,Jolly,Krüger,Zakrzewski
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p. 3520 - 3525
(2008/10/08)
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