including insulation of the perfluoroalkyl groups Syntheses and carbonyliridium complexes of unsymmetrically substituted fluorous trialkylphosphanes: Precision tuning of electronic properties

Reactions of iodides I(CH2)(m)R(f8) [m = 2-4; R(f8) = (CF2)7CF3] and LiPH2 DME (-45 C, THF) give the primary phosphanes PH2(CH2)(m)R(f8) (7-9; 48-76%). Radical-initiated reactions (100 C) of 7 and H2C=CHCH2R(f8), 8 and H2C=CHR(f8) or H2C= CHCH2CH2R(f8), and 9 and H2C=CHCH2R(f8), give the title phosphanes P[(CH2)(m)R(f8)]2[(CH2)(m')R(f8)] [m/m' = 2/3 (10), 3/2 (11), 3/4 (12), 4/3 (13); 70-76%]. The symmetrically substituted phosphane P[(CH2)(m)R(f8)]3 (m = 5, 6) is similarly prepared from PH3 and H2C=CHCH2CH2CH2R(f8), analogously to previously reported homologs [m = 2 (2), 3 (4), 4 (5)]. Reactions of 10-13 and 2, 4, 5, and 6 with [Ir(COD)Cl]2 and CO give trans-Ir(CO)(Cl)(PR2R')2 (70-83%). The IR V(CO) values show a monotonic decrease with increasing numbers of CH2 groups. Phosphanes 13, 5, and 6 have the most CH2 groups, and give V(CO) values 10, 7, and 4 cm-1 higher than the unfluorinated phosphane P[(CH2)7CH3]3. Hence, 6 provides nearly complete insulation of the iridium center from the electronegative perfluoroalkyl groups. Analogous rhodium derivatives of 4 and 5 are also described.

Syntheses and carbonyliridium complexes of unsymmetrically substituted fluorous trialkylphosphanes: Precision tuning of electronic properties, including insulation of the perfluoroalkyl groups Academic Article