Alkyl dehydrogenation in iridium tri-cyclopentyl phosphines

作者：Moret Severine; Dallanegra Romaeo; Chaplin Adrian B; Douglas Thomas M; Hiney Rachel M; Weller Andrew S^*

来源：Inorganica Chimica Acta, 2010, 363(3): 574-580.

DOI：10.1016/j.ica.2009.03.004

• Phosphine
• Alkene
• Iridium
• Dehydrogenation
• Anion

The iridium cyclooctadiene complex incorporating a tricyclopentyl phosphine ligand (PCyp(3)), Ir(eta(2):eta(2)-C8H12)(PCyp(3))Cl, has been prepared. Removal of the chloride from this complex using Na[BAr4F][Ar-F = C6H3(CF3)(2)] in CH2Cl2/arene solvent results in dehydrogenation (C-H activation followed by beta-H transfer) of one of the alkyl phosphine rings and formation of the complexes [Ir(eta(6)-C6H5X){PCyp(2)(eta(2)-C5H7)}][BAr4F] (X = H, F) which contain a hybrid phosphine-alkene ligand. These complexes are formed alongside another product (5-20% yield) that has been identified as [Ir(eta(2):eta(2)-C8H12){PCyp(2)(eta(2)-C5H7)}][BAr4F], which can be prepared in high yield by an alternative, and slightly modified, route. This complex is with a minor isomer that has been tentatively identified as [Ir(eta(2):eta(3)-C8H11)(H){PCyp(2)(eta(2)-C5H7)}][BAr4F], which results from allylic C-H activation of cyclooctadiene. Addition of H-2 to [Ir(eta(2):eta(2)-C8H12){PCyp(2)(eta(2)-C5H7)}][BAr4F] and its isomer in arene solvent (C6H5X, X = F, H) forms the dihydrido eta(6)-arene Ir(III) complexes [Ir(H)(2)eta(6)-C6H5X)(PCyp(3))][BAr4F]. In contrast, hydrogenation in CH2Cl2 alone results in the formation of [Ir(H)(2)(PCyp(3))eta(6)-(C3H3)(2)][BAr3F] in which the [BAr4F](-) anion is now acting as a ligand through one of its aryl rings. The fluorobenzene complex [Ir(H)(2)eta(6)-C6H5F)(PCyp(3))][BAr4F] can be cleanly converted to [Ir(eta(6)-C6H5F){PCyp(2(eta)(2)-C5H7)}]][BAr4F] by addition of the hydrogen acceptor tert-butylethene (tbe).

• 出版日期2010-2-15