ISSN:
0009-2940
Keywords:
Alkynes
;
Palladium complexes
;
Phosphane ligands
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Alkynylpalladium compounds trans-PdX(C≡C—R)(PMe3)2 [R = CMe3, X = Cl (1), I (19); R = CMe2OH, X = Cl (2), Br (10), I (11); R = c-Hex, X = Cl (3), Br (12), I (13); R = CHMe2, X = Br (4); R = CH2SiMe3, X = Cl (5), Br (14), I (15); R = COOEt, X = Br (6), I (7); R = Ph, X = Cl (8), I (17); R = n-Pr, X = N3 (16), I (20); R = n-Hex, X = I (21); R = SiPh3, X = Br (22)] and trans-PdX(C≡C—R)(PBu3)2 [R = SiMe3, X = Cl (9), I (18)] as well as trans-PdX(C≡C—R)(PPh3)2 [R = CMe3, X = Br (23); R = CH2SiMe3, X = Br (24), I (25)] are prepared by known methods. Thermal decomposition between 120 and 160°C results in a selective transformation only with trimethylphosphane complexes 1, 2, 10-, and 19. Oxidative trimerization of the alkynyl groups C≡C—CMe2R′ and C≡C—(c-Hex) affording the enediynyl compounds trans-PdX[C(C≡C—CMe2R′) = C(C≡C—CMe2R′)CMe2R′] (PMe3)2 [R′ = Me, X = Cl (26), I (27); R′ = OH, X = Cl (28), Br (29), I (30)] and trans-PdX{C[C≡C—(c-Hex)]=C[C≡C—(c-Hex)] (c-Hex)}(PMe3)2 [X = Br (31), I (32)] appears to be controlled by balanced steric demands of phosphorus and alkynyl substituents. The steric control is investigated by melting) transformable monoalkynyl complex trans-PdI(C≡C—CMe2OH)(PMe3)2 (11) with non-transformable[*] complex trans-PdI[C≡C—(n-Pr)](PMe3)2 (20) to give a mixture (A) of transformed complexes with mixed substituents R. Similar results are obtained in other mixtures, when transformable PdBr(C≡C—SiMe3)(PMe3)[1] is heated with the non-transformable complexes PdBr[C≡C—(n-Pr)](PMe3)2[1] and 20 (mixture B) or transformable PdBr[C≡C—(c-Hex)](PMe3)2 (12) with non-transformable PdBr[C≡C—(n-Pr)](PMe3)2[1] (mixture C).
Additional Material:
14 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19951280405
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