84558-22-5Relevant articles and documents
Transition-metal complexes of organoaluminum phosphides. Synthesis, characterization, and crystal and molecular structure of Cr(CO)5[PPh2Al(CH2SiMe3) 2·NMe3]
Tessier-Youngs, Claire,Bueno, Clifford,Beachley Jr.,Churchill, Melvyn Rowen
, p. 1054 - 1059 (2008/10/08)
The reactions of organoaluminum phosphides with a variety of transition-metal carbonyl complexes containing labile ligands have been investigated. The reaction of Cr(CO)5NMe3 with (Me3SiCH2)2AlPPh2 in benzene solution leads to the formation of Cr(CO)5[PPh2Al(CH2SiMe2) 2·NMe3], a fully characterized new compound. An X-ray structural study has identified discrete isolated molecules of Cr(CO)5[PPh2Al(CH2SiMe3) 2·NMe3], separated by normal van der Waals distances, in the monoclinic crystal space group P21/n with a = 11.839 (4) A?, b = 18.517 (5) A?, c = 16.158 (4) A?, β = 90.32 (2)°, and ρ(calcd) = 1.20 g/cm3 for Z = 4 with molecular weight 637.82. Diffraction data were collected with a Syntex P21 diffractometer, and the structure was refined to RF = 6.4% for all 4948 reflections. There are no abnormally short intermolecular contacts. The unusual features identified in the investigation are the long bond distances for Al-P of 2.485 (1) A? and Cr-P of 2.482 (1) A?. The Al-N bond seems to be normal. The geometry about the tetrahedrally coordinated phosphorus atom is decidedly irregular. Similarly, the aluminum atom has a rather distorted tetrahedral environment. The reaction of Cr(CO)5[PPh2Al(CH2SiMe3) 2·NMe2] with anhydrous HBr leads to the formation of Cr(CO)5PPh2H, Br3AlNMe3, and SiMe4. A likely path for this reaction involves the initial cleavage of the long P-Al bond. In attempts to find other preparative reactions to compounds with a Cr-P-Al bond sequence, the related reactions of Cr(CO)5L (L = CO, CH3CN, THF) with R2AlPPh2 (R = Me, Et) were studied but the desired compounds were not formed. Available data suggest that the labile ligand on chromium was attacked by the aluminum-phosphorus reagent.
