Transient infrared spectroscopy of (η5−C5 H5)Co(CO)2 photoproduct reactions in hydrocarbon solutions

Abstract

Ultrafast photochemistry of CpCo(CO)2 in n-hexane, 1-hexene, and solvent mixtures (298 K) are reported. Multichannel infrared spectra (0.4 ps, 4 cm−1 resolution) identify the vibrational cooling of CpCo(CO)(n-hexane) and CpCo(CO)(1-hexene). The conversion rate of transient n-hexane species to stable 1-hexene product for 0.2–2.0 mol/liter 1-hexene/n-hexane solutions (k=1.4±0.2×1010 M−1 s−1) was determined.

Femtosecond Mid-Infrared Study of the Aqueous Solution Photochemistry of a CO-Releasing Molecule (CORM)

“…Whereas it has been found that UV excitation of hexacarbonyls leads to a significant amount of molecules with vibrational hot bands in the CO stretch [4], that has not been observed in a study on dicarbonyls [5]. In the data of our CORM, no distinct hot bands are observed, hence the CO stretch of the photoproduct is not excited in the course of the photolysis.…”

“…in [4][5][6]), the photolysis of CO in water-soluble CORMs with suitable properties for biological applications have so far only been studied on a macroscopic scale and at irradiation times of several minutes. For the CORM studied here, UV irradiation eventually leads to the release of two [2] or even all three CO ligands [3].…”

Low‐Lying Excited States and Primary Photoproducts of [Os3(CO)10(s‐cis‐L)] (L=Cyclohexa‐1,3‐diene, Buta‐1,3‐diene)] Clusters Studied by Picosecond Time‐Resolved UV/Vis and IR Spectroscopy and by Density Functional Theory

“…The 1,3-diene ligand was assumed to retain its s-cis coordination at Os3. This tentative structure of the ns transient was found to correspond well to the fragmentation into {Os 2 (CO) 6 (m-CO)(L) 2 } and {Os(CO) 3 (1,3-diene)} in the presence of L = CO, olefin.…”

“…Be-clusters are usually too short-lived to be studied with nanosecond (ns) transient absorption (TA) or TRIR, faster spectroscopic techniques are required in order to characterise the excited states and to monitor the formation of the primary photoproducts. Although several picosecond (ps) TRIR studies of simple, mononuclear transition-metal complexes with, for example, M 0 (Cr, Mo, W [4] or Fe [5] ) and M I (Co, [6] Rh and Ir [7] ) centres have been reported, those of diand polynuclear transition-metal complexes are scarce.…”

“…The ps TRIR spectra do not reveal whether at l exc = 400 nm the p*(CO) orbitals are populated from a molecular orbital with predominant s(Os1ÀOs3) (HOMO) or s(Os1ÀOs2) (HOMOÀ2) character (Table 2). From the nature of the fragmentation products formed upon continuous-wave irradiation of cluster 1, [11] the Os1ÀOs2 bond connecting the two Os centres in the dinuclear photoproducts [Os 2 (CO) 6 (m-CO)(L) 2 ] (L= CO, ethene) should remain intact. As this reasoning does not agree with the depopulation of the HOMOÀ2 (Figure 3), it is proposed that the reactive sp* excited state should have s(Os1ÀOs3)p*(CO) (HOMO± LUMO) character.…”