Protonation and Hydrogen Atom Abstraction Reactions in the Synthesis of the [HP7M(CO)3]2– Ions (M = Cr, W)

✍ Scribed by Scott Charles; Janet A. Danis; Sundeep P. Mattamana; James C. Fettinger; Bryan W. Eichhorn

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: German
• Weight: 122 KB
• Volume: 624
• Category: Article
• ISSN: 0372-7874
• DOI: 10.1002/(sici)1521-3749(199805)624:5<823::aid-zaac823>3.0.co;2-z

✦ Synopsis

Ethylenediamine (en) solutions of [P 7 M(CO) 3 ] 3± (M = Cr, W) react with weak acids to give [HP 7 M(CO) 3 ] 2± ions where M = Cr (4 a) and W (4 b) in high yields. Competition studies with known acids revealed a pK a range for 4 b in DMSO of 17.9 to 22.6. The [P 7 M(CO) 3 ] 3± complexes also react with one-half equivalent of I 2 to give 4 through an oxidation/hydrogen atom abstraction process. Labeling studies show that the abstracted hydrogen originates from the [K(2,2,2-crypt)] + ions or from the solvent (DMSO-d 6 ) in the absence of [K(2,2,2-crypt)] + or other good hydrogen atom donors. In the solid state, the ions have no crystallographic symmetry but in solution they show virtual C s sym-metry ( 31 P NMR spectroscopy) due to an intramolecular wagging process. Crystallographic data for [K(2,2,2crypt)] 2 [HP 7 W(CO) 3 ]: triclinic, P 1, a = 10.9709( ) A Ê , b = 13.9116(10) A Ê , c = 19.6400(14) A Ê , α = 92.435(6)°, b = 93.856(6)°, c = 108.413(6)°, V = 2831.2(4) A Ê 3 , Z = 2, R(F) = 7.65%, R(wF 2 ) = 14.17% for all 7400 reflections. For [K(2,2,2-crypt)] 2 [HP 7 Cr(CO) 3 ]: triclinic, P 1, a = 12.000(3) A Ê , b = 14.795(3) A Ê , c = 17.421(4) A Ê , α = 93.01(2)°, b = 93.79(2)°, c = 110.72(2)°, V = 2877(2) A Ê 3 , Z = 2.