Sulphonated ligands

Rhone-Poulenc and Ruhrchemie (now Hoechst) developed a process in the 1980s based on a water soluble rhodium catalyst modified with triphenylphosphine sulphonate ligand that can produce normal to iso ratios as high as 20. Previous phosphine modified rhodium catalysts were oil soluble. 

Finally a variety of 1-alkenes were hydroformylated with a highly water-soluble tris-sulphonated ligand, P(m-PhS03Na). Some more effective catalysts involving the use of other sulphonated phosphine ligands have also been developed. ... 

A very few coordination complexes of tetramethylene sulphone [(CH2)4S02] with transition metal ions have been prepared, and the coordinative ability of sulpholane is generally regarded as quite weak224,225. Sulpholane metal complexes should therefore serve as excellent precursors of the coordination compounds containing other weakly nucleophilic ligands. 

Bicyclic sulphones, reactions of 279, 280 Bicycloannulation 778 Biological oxidation 76-78, 987, 988 Bis(alkylsulphinyl)alkanes, as bidentate ligands 571, 572... 

In conforming to an expected linear free energy relationship, the Ce(lV) oxidation of various 1,10-phenanthroline and bipyridyl complexes of Ru(II) in 0.5 M sulphuric acid are consistent with the requirements of the Marcus treatment . The results for the oxidation of the 3- and 5-sulphonic-substituted ferroin complexes by Ce(IV) suggest that the ligand does not function as an electron mediator, and that the mechanism is outer-sphere in type. Second-order rate coefficients for the oxidation of Ru(phen)j, Ru(bipy)3, and Ru(terpy)3 are 5.8x10, 8,8 X 10, and 7.0 x 10 l.mole . sec, respectively, in 0.5 M H2SO4 at 25 °C a rapid-mixing device was employed. 

Miscellaneous Reactions of Phosphines.- The role of chiral phosphines as ligands in the catalysis of reactions leading to the formation of chiral products has been reviewed.1111 A procedure for the determination of the enantiomeric excess in chiral phosphines has been developed, based on 13C n.m.r. studies of the diastereoisomeric complexes formed by phosphines with the chiral pinenyl nickel bromide complex. 111 Studies of the sulphonation of triphenylphosphine and of chiral arylphosphines have been reported in attempts to prepare water soluble ligands which aid... 

In 1986 a new process came on stream employing a two-phase system with rhodium in a water phase and the substrate and the product in an organic phase. For propene this process is the most attractive one at present. The catalyst used is a rhodium complex with a sulphonated triarylphosphine, which is highly water-soluble (in the order of 1 kg of the ligand "dissolves" in 1 kg of water). The ligand, tppts (Figure 8.6), forms complexes with rhodium that are most likely very similar to the ordinary triphenylphosphine complexes (i.e. RhH(CO)(PPh3)3). 

Mg has been studied in a polyelectrolyte system where the counterion is a phosphazene-bound sulphonate group. In this case the finite but low conductivity is due to Mg migration. A large increase in conductivity is noted when a bicyclic ligand, crypt [2.1.1.], is introduced (Hancock and Martell, 1988). Apparently, the cation-anion and cation-polymer interactions are reduced by complex formation, resulting in a more mobile cation, despite its larger effective radius. 

SWV has been applied to study electrode reactions of miscellaneous species capable to form insoluble salts with the mercury electrode such as iodide [141,142], dimethoate pesticide [143], sulphide [133,144], arsenic [145,146], cysteine [134, 147,148], glutathione [149], ferron (7-iodo-8-hydroxyquinolin-5-sulphonic acid) [150], 6-propyl-2-thiouracil (PTU) [136], 5-fluorouracil (FU) [151], 5-azauracil (AU) [138], 2-thiouracil (TU) [138], xanthine and xanthosine [152], and seleninm (IV) [153]. Verification of the theory has been performed by experiments at a mercury electrode with sulphide ions [133] and TU [138] for the simple first-order reaction, cystine [134] and AU [138] for the second-order reaction, FU for the first-order reaction with adsorption of the ligand [151], and PTU for the second-order reaction with adsorption of the ligand [137]. Figure 2.90 shows typical cathodic stripping voltammograms of TU and PTU on a mercuiy electrode. The order of the... 

The thenoyltrifluoroacetate (tta) complex, [Sc tta)3 OP(OBu)3)], has been prepared. Scandium also afforded, with l,2-dihydroxybenzene-3,5-disodium sulphonate (Tiron), a monoprotonated chelate below pH 2.5, but above pH 6.0 hydrolysis afforded a monohydroxo-Sc-Tiron complex. Ligand-exchange equilibria for the piperidium salts of [Y(ffac)4] and [Y(tfac)4] have been studied by n.m.r. spectroscopy. The fully fluorinated ligands appear to exchange faster than the partially fluorinated species, and the mixed compounds, [Y(Hffac) (tfac)4 ] , n = 0 — 4, were obtained. 

Unlike the specifically bound metals which participate in reversible redox reactions extraneously bound transition metals are well able to induce uncontrolled oxidation of sulphur containing ligands The so called metal driven Haber Weiss reaction is responsible for the formation of oxidised sulphur species leading to sulphonic acid. For example ... 

The enhancement in the receptor capacity to host anions has been successfully achieved by the design of double-cavity ligands. This is reflected in the conductometric titration curve (Fig. 4c) for the fluoride anion when titrated with receptor 7. In fact, in A/,A/-dimethylformamide, this receptor takes up two anions per unit of ligand while discriminating against other spherical (chloride, bromide and iodide) and non-spherical (hydrogen sulphate, perchlorate, nitrate and tri-fluoromethane sulphonate) anions except H2POj. With this anion only the formation of a 1 1 complex was observed. 

Coordination of NO to the iron results in labilization of the quinoline moiety and fluorescence decrease [94], Other NO sensors are based on Fe [102], Mn [95], and Co [103-105] tropocoronand complexes. One example is shown in Figure 16.23. The tropocoronand ligands incorporate substituted dimethylaminonaphthalene sulphonate fluorophores. Free ligands exhibit strong fluorescence, which is largely... 

A breakthrough occurred in the mid-seventies when Union Carbide and Celanese introduced Rh/phosphine catalysts in commercial processes. This catalyst is based on the work by Wilkinson s group he received the Nobel prize for his work in 1973. Rhodium-based catalysts are much more active than cobalt catalysts and, under certain conditions, at least for 1-alkenes, they are also more selective. The processes for the hydroformylation of higher alkenes (detergent alcohols) still rely on cobalt catalysis. A new development is the use of water-soluble complexes obtained through sulphonation of the Ligands (Ruhrchemie). 

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