Synthetic, Thermochemical, and Catalytic Studies Involving Novel R₂P(OR_f) [R = Alkyl or Aryl; R_f = CH₂CH₂(CF₂)₅CF₃] Ligands

Abstract

A series of mixed alkyl (or aryl) phosphinite compounds have been prepared from the alcohol CF3(CF2)5CH2CH2OH (RfOH) and an appropriate ClPR2 (R = ORf, Ph, iPr, Cy) in the presence of base. A bidentate analog, (RfO)2PCH2CH2P(ORf)2, was synthesized in a similar manner. The ligands react with [Rh(CO)2Cl]2 yielding the complexes RhCl(CO)(PR3)2. The structure of RhCl(CO)(PPh2ORf)2 (6) is reported. Infrared studies of the carbonyl complexes yield a relative ligand donor strength for this series. Solution calorimetry was performed on the rhodium reaction in order to quantify this donor strength scale. Both approaches lead to the same donor strength scale: PCy2ORf > PiPr2ORf > PPh2ORf > P(ORf)3. These phosphinite ligands can be used as ancillary ligation in rhodium-mediated hydrogenation. A cationic rhodium complex of the chelating ligand displays selected solubility in fluorous media and biphasic catalysis can be performed.

New aryl phosphinite ligands avoiding ortho-metallation: Synthesis and molecular structures of trans-[PdCl2(PPh2OR)2] and trans-[Rh(CO)Cl(PPh2OR)2] (R=2,4,6-Me3C6H2; 2,6-Ph2C6H3)

“…Significant bond lengths and bond angles are listed in Table 3. The Rh-CO distance of 1.834(4) Å in 5 is similar to the one in [Rh(CO)Cl{PPh 2 OR f }] 2 [15], the only example of trans Rh complex containing phosphinite ligands, while the C-O distance (1.105(4) Å ) is slightly shorter by 0.018 Å , consistent with a slightly weaker Rh-CO interaction in 5. The Rh-P and Rh-Cl distances in 5 are similar to those of this complex.…”

Fluoroarylphosphines as ligands

“…This has been confirmed for rhodium(I) complexes in an investigation of substitution enthalpies, determined by calorimetry of the reaction between [Rh(CO) 2 (m-Cl)] 2 and phosphines of similar cone angles, which show a dependence on electronic properties: P(C 6 H 4 CF 3 -4) 3 [110]. The greater bulk of fluoroarylphosphines is also expected to affect adversely complex stability by increasing steric congestion, and in some cases can prevent complex formation, for example [(h 5 -C 5 Me 5 )RhCl 2 {PPh 3Àx (ArF) x )], ArF = C 6 F 5 , C 6 H 3 F 2 -2,6, have been prepared for x = 0 and 1, but the attempted syntheses of the complexes with x = 2 and 3 were unsuccessful [57,111].…”

“…A more useful indicator of metal electronic character is n(CBBO), since this shows a greater range of frequency and the carbonyl ligand is a common spectator ligand in organometallic chemistry. The effect of fluorination of diphosphines is evident from n(CBBO) of complexes such as [Mo(CO) 4 [117] 1964 PPh 2 (C 6 F 5 ) [20] 1982 PPh 2 (C 5 H 4 N-2) [118] 1969 PPh 2 (C 6 F 4 CBBN-4) [120] 1987 P(C 6 H 4 SO 3 Na-3) 3 [119] 1973 PPh 2 (C 5 F 4 N-4) [42] 1993 P(C 6 H 4 F-4) 3 [110] 1982 P{C 6 H 3 (CF 3 ) 2 -3,5} 3 [47] 2000 P(C 6 H 4 Cl-4) 3 [110] 1984 Cone angle % 1718 P(C 6 H 4 CF 3 -4) 3 [110] 1990 PPh(C 6 H 3 F 2 -2,6) 2 [57] 1961 PPh(C 6 F 5 ) 2 [20] 2002 Cone angle % 1848 P(C 6 H 3 F 2 -2,6) 3 [57] 1965 P(C 6 F 5 ) 3 [20] 2008…”

Coordination chemistry of perfluoroalkylated phosphorus(III) ligands

“…Turning now to the palladium(II) complexes, 31 [27,28], (27) and (29) [29] have been described previously. trans-[IrCl(CO)L 2 ] (L = L1, L2, L3; 32,33,34) are prepared by carbonylation of the product from the cleavage of [IrCl(COD)] 2 with the respective phosphines; trans-[IrCl(CO)(L3) 2 ] (34) has been described previously [28].…”