For an axially perturbed (C4v) Re2(CO)10 molecule, the CO stretch representation was found to be 2E+B1+B2+3A1, where the IR active modes are 2E+3A1. Its identity can also be confirmed by mass spectrometry, using the isotopic pattern of rhenium (185Re and 187Re). Dirhenium decacarbonyl may be obtained by reductive carbonylation of rhenium(VII) oxide (Re2O7) at 350 atm and 250 °C. The carbonyl ligands may be displaced by other ligands such as phosphines and phosphites (denoted L). This compound may also be "cracked" to mononuclear Re(I) carbonyl complexes by halogenation:  When bromine is used, bromopentacarbonylrhenium(I) is formed, which is an intermediate for many more rhenium complexes. This compound may also be hydrogenated to form various polyrhenium complexes, eventually giving elemental rhenium. In the presence of water, photolysis of Re2(CO)10 yields a hydroxide complex:  This reaction includes the cleavage of Re-Re bond and the synthesis of HRe(CO)5, which can be used to prepare surface structures designed to incorporate isolated surface-bound Re carbonyl complexes. Loss of a carbonyl ligand by photolysis generates a coordinatively unsaturated complex that undergoes oxidative addition of Si-H bonds, for example:  Rhenium-based catalysis have been used in metathesis, reforming, hydrogenation and various hydrotreating processes such as hydrodesulfurization. Re2(CO)10 can be used to promote the silation of alcohols and prepare the silyl ethers, and its reaction: