In loving memory of Dr. Julio Real The stereoelectronic properties of a series of trifluoromethylated aromatic phosphines have been studied using different approaches. The σ-donating capability has been evaluated by nuclear magnetic resonance (NMR) spectroscopy of the selenide derivatives and the protonated form of the different trifluoromethylated phosphines. The coupling constants between phosphorous and selenium (1 J SeP) and phosphorous and hydrogen (1 J HP) can be predicted by empirical equations and correlate the basicity of the phosphines with the number and relative position of trifluoromethyl groups. In contrast, the π-acceptor character of the ligands has been evaluated by measuring the frequency of the CO vibration in the infrared (IR) spectra of the corresponding Vaska type iridium complexes ([IrCl(CO)(PAr 3) 2 ], PAr 3 = triarylphosphine). Moreover, the correlation between the electronic properties and the performance of these phosphines as ligands in the rhodium-catalysed hydroformylation of 1-octene has been established. Phosphines with the lowest basicity, that are those with the highest number of trifluoromethyl groups, gave rise to more active catalytic systems.

QHZ VHULHV RI VXOIRQDWHG WULDU\OSKRVSKLQHV ZLWK VWURQJ OE-acceptor character were synthesized by direct sulfonation of trifluoromethylated neutral phosphines. Due to the deactivating character of the trifluoromethyl group, high oleum concentration and the use of boric acid to prevent phosphines to be oxidized were required for the sulfonation step. The new sulfonated phosphines are water soluble and more inert toward oxidation than classical sulfonated phosphines. The use of these trifluoromethylated and sulfonated phosphines as ligands in the biphasic hydroformylation of vinyl acetate and allyl cyanide increases the rate of the reaction up to 4 times, compared to the results obtained with the non-trifluoromethylated counterparts, TPPMS, TPPDS and TPPTS. Moreover, it is possible to recycle the catalyst without a significant loss of the system activity.

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Enantiopure bis(diamidophosphite) ligands with a heterocyclic terminal fragment derived from (R)-and (S)-N,N′-dimethyl-1,1′-binaphthyldiamine and bridging fragments derived from (S,S)-2,3-butanediol (a), (4R,5R)-4,5-di(hydroxymethyl)-2,2-dimethyl-1,3-dioxolane (b), and (R)-and (S)-1,1′-bi-2-naphthol (c) were used to prepare the palladium complexes with general formula [Pd(η 3 -2-CH 3 -C 3 H 4 )(P-P)][X] (X = PF 6 , 1a-(S;S al ,S al ;S), 1b-(R;R al ,R al ;R), 1b-(S;R al ,R al ;S), 1c-(R;R al ;R), 1c-(R;S al ;R); X = BPh 4 , 2a-(R;S al ,S al ;R), 2c-(R;R al ;R)), which have been fully characterized. The solid-state structure for complexes 1a-(S;S al ,S al ;S) and 1b-(R;R al ,R al ;R) has been determined by X-ray diffraction. The catalytic performance of the palladium complexes has been evaluated in asymmetric allylic alkylation and amination reactions with the benchmark substrate. The influence of the nature and absolute configuration of both the terminal and bridging fragments of the bis(diamidophosphite) ligands on the asymmetric induction is discussed. The best results in terms of enantioselectivity were obtained with 1c-(R;R al ;R), affording enantiomeric excesses up to 85% in both alkylation and amination reactions. A large match−mismatch effect between the absolute configurations of stereocenters of ligand c has been observed in the allylic amination process. Preliminary results in the rhodiumcatalyzed asymmetric hydroformylation of styrene by using bis(diamidophosphite) ligands a, b, and c disclosed in all cases low enantiomeric discrimination for the branched aldehyde. Both for the allylic alkylation and for the hydroformylation reaction, a related monodentate diamidophosphite d, derived from (R)-N,N′-dimethyl-1,1′-binaphthyldiamine and (S)-borneol, was also tested. Palladium complexes of this monodentate ligand showed fairly good enantioselectivity in allylic alkylation, but with very low rate, while the rhodium complex of d rendered better enantioselectivity (37% ee) than the bidentate ligands a−c in the hydroformylation of styrene.