Synthesis, structure, and reactivity of fluorous phosphorus/carbon/phosphorus pincer complexes derived from P(CH2)5P backbones

Reactions of the diphosphine H2P(CH2)(5)PH2 and fluorous alkenes H2C=CHRfn (excess; R-fn=(CF2)(n-1)CF3; n = a, 6; b, 8; c, 10) at 60 degrees C in the presence of AlBN give the precursors (RfnCH2CH2)(2)P(CH2)(5)P(CH2CH2Rfn)(2) (2a-c; 68-74%). These react with Pd(O2CCF3)(2) in CF3C6F5 at 80 degrees C to give the title complexes (RfnCH2CH2)(2)P(CH2)(2)CH(CH2)(2)P(CH2CH2Rfn)(2)Pd(O2CCF3) (5a-c, 51-18%). Addition of LiCl to 5b gives (Rf8CH2CH2)(2)P(CH2)(2)CH(CH2)(2)P(CH2CH2Rf8)(2)PdCl (6b, 97%); subsequent reaction with MeLi affords the corresponding methyl complex (97%). A solvate of 6b is crystallographically characterized. The structure exhibits CH2CH2Rf8 groups with nearly anti C-C-C-C conformations, extending in parallel above and below the palladium square plane to create fluorous lattice domains. Reactions of 2b and other metal complexes are described; in the cases of (PhCN)(2)PdCl2 or (COD)(2)PtCl2 (CF3C6H5, room temperature), bimetallic species in which two MCl2 moieties are bridged by two diphosphines appear to form. The CF3C6F11/toluene partition coefficients of 2a-c and 5a-c establish high fluorophilicities; despite the lower fluorine weight%, those of 5a-c are slightly greater ((97.4-99.7):(2.6-0.3) versus (95.3-99.3):(4.7-0.7)). (c) 2006 Elsevier B.V. All rights reserved.