REMARKABLE STABILITY OF (ETA(5)-C5H5)RE(CO)(2)L (L=N-HEPTANE, XE, ANDKR) - A TIME-RESOLVED INFRARED SPECTROSCOPIC STUDY OF (ETA(5)-C5H5)RE(CO)(3) IN CONVENTIONAL-FLUID AND SUPERCRITICAL-FLUID SOLUTION

Employing fast time-resolved infrared (TRIR) spectroscopy we have char acterized CpRe(CO)(2)(n-heptane), CpRe(CO)(2)(Xe), and CpRe(CO)(2)(Kr) (Cp = eta(5)-C5H5)(-) or above room temperature in n-heptane, supercr itical Xe, and Kr solution. The reactivity of CpRe(CO)(2)(n-heptane) w ith CO (k(2) = 2.1 (+/-0.5) x 10(3) mol(-1) dm(3) s(-1)) shows this co mplex to be the least reactive of the reported organometallic alkane c omplexes. We report a trend in reactivity of the early transition meta l alkane complexes. CpRe(CO)(2)(Xe) and CpRe(CO)(2)(Kr) are also shown to have significant stability. CpRe(CO)(2)(Xe) is less reactive towar d CO than all of the reported alkane complexes except CpRe(CO)(2)(n-he ptane).