PREPARATION, MOLECULAR-STRUCTURE AND REACTIVITY OF MONONUCLEAR AND DINUCLEAR SULFONATO RHODIUM(I) COMPLEXES

The reaction of [Rh(eta(3)-C3H5)(PPr3i)(2)] 1 or [Rh(eta(3)-CH2Ph)(PPr 3i)(2)] 2 with an equimolar amount of RSO3H (R = Me, p-tolyl, CF3, F, Camph) led to the formation of the monomeric sulfonatorhodium(I) compl exes [Rh{eta(2)-O2S(O)R}-(PPr3i)(2)] 3-7 in excellent yield. An altern ative route for the preparation of 4 (R = p-tolyl) and 5 (R = CF3) is based on the reaction of PPr3i, with the dinuclear compounds [{Rh(C8H1 4)(2)[mu-O2S(O)R]}(2)], which were obtained either from [{Rh(C8H14)(2) (mu-Cl)}(2)] 8 or [{Rh(C8H14)(2)(mu-OH)}(2)] 9 as starting materials. Compounds 3-7 react smoothly with hydrogen by oxidative addition to gi ve the dihydridorhodium(III) complexes [RhH2{eta(2)-O2S(O)R} (PPr3i)(2 )]. Moreover, on treatment of 3-6 with CO and C2H4 the chelating bond of the sulfonate ligand is partially opened and the carbonyl and ethen e complexes trans-[Rh{eta(1)-OS(O)(2)R}(L)(PPr3i)(2)] (L = CO or C2H4] are formed. The bis(stibine)-rhodium(l) derivative trans-[Rh{eta(1)-O S(O)(2)CF3}(C2H4)(SbPr3i)(2)] was obtained from [{Rh(C2H4)(2)[mu-O2S(O )CF3]}(2)] and SbPr3i. Reaction of the compounds [Rh{eta(2)-O2S(O)CF3} (olefin)(PPr3i)] (olefin = C8H14 or C2H4) with benzene led to the disp lacement of the sulfonate ligand and to the formation of the half-sand wich-type complexes [Rh{eta(6)-C6H6)- (olefin)CPP3i)][CF3SO3] containi ng a rather labile benzene-rhodium bond. The preparation of the vinyli dene complex rans-[Rh{eta(1)-OS(O)C6H4Me-p}(=C=CHPh)(PPr3i)(2)] is als o described and the crystal and molecular structures of three compound s have been determined. The four-co-ordinate sulfonato complexes 3-6 a re active catalysts in the C-C coupling reaction of ethene and dipheny ldiazomethane. Besides the three isomeric 1:1 adducts of C2H4 and CPh2 , quite unexpectedly also the 2:1 adduct 3,3-diphenylpent-1-ene is for med.