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The heterogenization of the zwitterionic Rh(I) catalysts (sulfos)Rh(cod) (1) and (sulfos)Rh(CO)2 (2) [sulfos = -O3S(C6H4)CH2C(CH2PPh2)3; cod = cycloocta-1,5-diene] is performed by controlled adsorption on partially dehydroxylated high surface area silica. The immobilization procedure is based uniquely on the capability of the sulfonate tail of sulfos to link the silanol groups of the support via hydrogen bonding. Experimental evidence of the −SO3···HOSi− interaction between 1 or 2 and silica has been obtained from IR, Rh K-edge EXAFS, and CP MAS 31P NMR studies. The grafted catalyst (sulfos)Rh(cod)/SiO2 (1/SiO2) is active for the hydrogenation of alkenes in either flow reactors (ethene, propene) or batch reactors (styrene) in hydrocarbon solvents. The hydroformylation of alkenes, here exemplified by 1-hexene, is catalyzed exclusively in solid−liquid conditions. No Rh leaching is observed in either case. In solid−gas conditions, the catalyst 1/SiO2 is converted by syngas to the catalytically inactive, dicarbonyl derivative (sulfos)Rh(CO)2/SiO2 (2/SiO2). The termination metal products of the solid−gas reactions have been studied by EXAFS, while those of the batch reactions have been authenticated by NMR spectroscopy after extraction with methanol. In all of the cases investigated there was no evidence of the formation of contiguous Rh−Rh sites, indicating that the catalytic active sites are isolated Rh atoms, as in homogeneous phase. A comparison with analogous hydrogenation and hydroformylation reactions catalyzed by the soluble complex 1 in liquid-biphase conditions shows that the immobilized catalyst is more chemoselective and more easily recyclable than the unsupported analogue.

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The q4-benzene complex [(triphOS)h(C6H6)] BPh4 reacts with thiophene to give the iridathiabenzene complex [(triphos)Ir(qW,S-C4H4S)]BPh4 (1) [triphos = MeC(CH2PPh2)J. Compound 1 is selectively converted to the butadienethiolatecomplex [ (triphos)Ir(q3-SCH=CHCH=CH2)] (2) by reaction with LiHBEt3 via the (thiapentadieny1)-hydride kinetic intermediate [(triphas)IrH(q2-C,S-C4H4S)] (3). Compound 2 is straightforwardly obtained by reaction of [(tripho~)Ir(H)~(C2Hs)l with thiophene. This reaction produces also the (2-thieny1)dihydride [(triphos)Ir(H)z-(2-C4H3S)] (4) through a parallel C-H bond activation path. The thienyl complex is not a kinetic intermediate for the opening reaction of thiophene. Compound 2 reacts with HBFcOEt2 in the presence of CO yielding the thiocrotonaldehyde complex [(triphos)Ir(CO)(q4-S=CHCH=CH(Me))]BF4 (5) and with PhSH to give the allylthioaldehyde derivative [(triphos)Ir(SPh)(q4-S=CHCH2CH=CH2)] (6). The latter compound is stable in the solid state, but re-forms 2 and PhSH in solution unless an excess of thiophenol is added. Stirring 2 with a 5-fold excess of HCl produces the trichloride [(triphos)IrC13], H2S, CH2=CHCH=CH2, C H~= C H C H Z C H~S H , and CH3CH2-CH=CHSH. Methylation of 2 with MeI, followed by NaBPh4 addition, gives the methyl buta-1,3-dienyl thioether complex [ (triphos)Ir(q3-S(Me)CH=CHCH=CH2)]BPh4.0.5EtOH (8) which has been characterized by a singlecrystal X-ray analysis. Compound 8 crystallizes in the space group P 2 ] / n . The coordination geometry around the iridium center is a distorted octahedron. The phosphorus atoms of triphos occupy threefuc positions of the coordination polyhedron. The coordination of the metal fragment is completed by the thioether ligand which uses the sulfur atom and the two carbon atoms of the distal olefinic moiety to bind the metal. Compound 8 reacts with gaseous HC1 converting to [(triphos)IrC13] and evolving CH*=CHCH2CH2SMe and CH3CH2CH=CHSMe. Treatment of 8 with THF-BHj, followed by R O H addition (R = Me, Et), gives [(triphos)IrH(SMe)(ROH)]BPh4 (R = Me, 9; Et, 10) and buta-1,3-diene. All reactions have been carried out in tetrahydrofuran.

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The P4 molecule bound to ruthenium as an eta1-ligand in [CpRu(PPh3)2(eta1-P4)]Y (Y = PF6, CF3SO3) undergoes an easy reaction with water in exceedingly mild conditions to yield PH3, which remains coordinated to the [CpRu(PPh3)2] fragment, and oxygenated derivatives.