The 310 nm photodissociation of dimanganese decarbonyl, Mn-2(CO)(10), in cyclohexane has been studied using ultrafast infrared spectroscopy. Subpicosecond IR detection near 5 mu m, in the region of carbonyl stretch vibrations, is carried out using a frequency-resolved broad (> 100 cm(-1)) IR probe pulse. The evolution of infrared spectra provide information on Mn-2(CO)(10) and its photoproducts. In the terminal carbonyl region (1970-2050 cm(-1)), bleach signals are observed due to loss of the parent compounds. A broad, featureless absorption appears promptly and narrows upon vibrational cooling (on the 50 ps time scale) to reveal IR spectral features consistent with those previously assigned to two photoproducts, Mn(CO)(5) and Mn-2(CO)(9). The bleach signals partially recover, indicating ground state recovery of vibrationally excited Mn-2(CO)(10), which is consistent with previous reports of geminate recombination. Mn-2(CO)(9) signal appearance times are 54(4) ps for the terminal CO band at 2052 cm(-1) and 31(5) ps for the bridge band at 1760 cm(-1). The direct observation of the bridging band establishes 31 ps as an upper limit for the bridge bond formation. The time dependence of the signal is probably due primarily to vibrational cooling of low frequency modes. The times are somewhat longer than the shorter of two times measured in the visible region and attributed to low frequency mode thermalization by Zhang and Harris [J. Chem. Phys. 95, 4024 (1991)]. Vibrational coherence effects were observed at early times (close to the vibrational dephasing time).