85883-61-0Relevant articles and documents
The reaction chemistry of transition-metal diphenylphosphorus complexes with organoaluminum compounds. The synthesis, characterization, and crystal and molecular structure of Cr(CO)5[PPh2(CH2)4OAl(CH 2SiMe3)2], an example of THF cleavage
Tessier-Youngs,Youngs, Wiley J.,Beachley Jr.,Churchill, Melvyn Rowen
, p. 1128 - 1138 (2008/10/08)
Metathetical and small molecule elimination reactions between appropriate transition-metal carbonyl diphenylphosphorus complexes and organoaluminum compounds have been investigated as synthetic routes to transition-metal derivatives of amphoteric ligands. The synthesis, characterization, and properties of the starting compounds for the metathetical reactions M(CO)5PPh2K·n(dioxane) (M = Cr, W, n = 2; M = Mo, n = 1) from M(CO)5PPh2H and KH are described. All data confirm that the dioxane molecules in these complexes retain their identity as cyclic ethers. Subsequent reactions of Cr(CO)5PPh2K·2(dioxane) with AlR2Br (R = Br, Me, Et, CH2SiMe3) in THF lead to the formation of high yields of fully characterized compounds with the empirical formula Cr(CO)5[PPh2(CH2)4OAlR2]. The (CH2)4O unit arises from the cleavage of the THF molecule. No THF-aluminum adducts are observed. The compound Cr(CO)5-[PPh2(CH2)4OAl(CH 2SiMe3)2] which incorporates a new amphoteric ligand has also been characterized by an X-ray structural study. The crystal is composed of dimeric units of formula [Cr(CO)5[PPh2-(CH2)4OAl(CH 2SiMe3)2]]2 which are in the centrosymmetric monoclinic space group P21/n with a = 11.939 (3) A?, b = 14.940 (A?), c = 21.014 (5) A?, β= 102.88 (2)°, V = 3654 A?3, Z = 2 (dimeric units), and mol wt 1301.5. Diffraction data (20(max) = 35°, Mo Kα radiation) were collected with a Syntex P21 automated four-circle diffractometer, the structure was solved by Patterson and difference-Fourier techniques, and the model was refined to RF = 9.2% and RwF = 8.2% for 1515 reflections with |Fo| > 3σ(|Fo|). The dimeric molecule lies on an inversion center. Each octahedral (OC)5CrPPh2- fragment is linked by an -(CH2)4O-unit (formed by cleavage of THF) to the two Al(CH2SiMe3)2 fragments. The central Al-O-Al-O ring is strictly planar, with obtuse Al-O-Al angles of 100.3 (6)° and acute O-Al-O angles of 79.7 (5)°. The second route to chromium derivatives of amphoteric aluminum-phosphorus ligands, small molecule elimination reactions between Cr(CO)5PPh2H and AlMe3 or AlMe2H, does not lead to compounds with Cr-P-Al bonds. Our observations suggest that the major site of reaction for the aluminum compounds is the carbonyl ligand.
