HYDROFORMYLATION OF 2,4,4-TRIMETHYL-1-PENTENE CATALYZED BY THE HIGH-NUCLEARITY CARBONYL CLUSTER [RH-12(CO)(30)](2-)

The salt Na-2[Rh-12(CO)(30)] was used for the hydroformylation of 2,4, 4-trimethyl-1-pentene in tetrahydrofuran under high pressures of CO/H- 2 (20-120 atm) in the temperature range 300-400 K. The reaction is hig hly chemioselective, approaching 100% selectivity to 3,5,5-trimethylhe xanal, and only traces of 2,4,4-trimethylpentane and 3,5,5-trimethyl-1 -hexanol are produced. Typical turnover numbers are 100-1000 mol olefi n/mol cluster. The cluster precursor was transformed into derivatives of lower nuclearity, [Rh-6(RCO)(CO)(15)](-) (R = (CH3)(3)CCH2CH(CH3)CH 2) or [Rh-5(CO)(15)](-), as shown by infrared spectroscopy. The turnov er numbers increase on lowering the catalyst to olefin ratio, and the order of the reaction with CO is positive. The dependencies of the rat es versus CO and catalyst concentrations suggest that, irrespective of the actual species present in solution, all the clusters behave in th e same way, probably through a CO-driven equilibrium of fragmentation.