Whether similar carbonyl complexes of the group 3 metals can be prepared and isolated is currently under investigation.
Experimental Procedure
In a typical synthesis of 2, a cold solution (-60°C) of NaC,,H, (1.30g, 8.6 mmol) in 80 mL of 1,2-dimethoxyethane (DME) was added by cannula to a mechanically stirred solution/slurry of HfCI, 2THF (2.0 g. 4.3 mmol) and PMe, (1.8 mL, 18 mmol) in 70 mL of DME at -60 "C. Addition of a cold solution ( -60°C) of NaSnPh, (6.42 g, 17.2 mmol) in 100 mL of DME to the resulting red-brown solution caused the color to change rapidly to a deep green. Argon was replaced by CO ( I atm) and the reaction mixture was stirred under CO for 12 h. while slowly warming to room temperature, to give a deep red solution. After filtration and cation exchange (with Et,NBr), a red solid was obtained upon addition ofexcess ethanol. Recrystallization of the product from CH,CN-toluene provided deep purple crystals (5.1 g, 61 Oh), which gave satisfactory analyses (C, H, Sn) for 2 as a bis-tetraethylammonium salt. Similar yields (50-60%) were obtained for the nPr,Ne salt (correct C. H analyses). The same procedure consistently provided lower yields (25-45%) of satisfactorily pure 1 as Et,Ne and nPr,N@ salts (C. H, Sn analyses). These substances are stable indefinitely under nitrogen at room temperature and decompose without melting above 150 'C. Spectroscopic data for the anions as Et,Ne or nPr,Ne salts are essentially identical and are shown only for the Et4Ne compounds [lo-121. The 99% enriched I3CO complexes were prepared by the same procedure with suitably enriched CO. X-ray quality crystals were obtained by slow diffusion of diethyl ether into an acetonitrile solution of the nPr,N@ salts at 0°C over a 3-5-day period. Suitable crystals could not be obtained with the less soluble E 4 N e salts.