Employing fast time-resolved infrared (TRIR) spectroscopy we have characterized CpRe(CO)2(n-heptane), CpRe(CO)2(Xe), and CpRe(CO)2(Kr) (Cp = η5-C5H5) at or above room temperature in n-heptane, supercritical Xe, and Kr solution. The reactivity of CpRe(CO)2(n-heptane) with CO (k2 = 2.1 (±0.5) x 103 mol-1 dm3 s-1) shows this complex to be the least reactive of the reported organometallic alkane complexes. We report a trend in reactivity of the early transition metal 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 toward CO than all of the reported alkane complexes except CpRe(CO)2(n-heptane).
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