The photoCORM fac-[Re (bpy)(CO) 3 (thp)](CF3SO3)(1, bpy= 2, 2′-bipyridine, thp= tris (hydroxymethyl)-phosphine) was prepared as originally described. NMR and elemental analysis were performed on 1 to provide complete characterization, and these data have been added to the revised Supporting Information provided herein. The photoluminescence (PL) from photoproduct 2 was not reproducible. Thus, statements in the Abstract and elsewhere that photoproduct 2 is luminescent are not correct. The residual PL upon photolysis of 1 apparent in Figure 6 (bottom) was likely due an impurity produced during synthesis/purification, a probable candidate being fac-[Re-(CO) 3 (bpy)(OH2)](OTf)(A), formed from fac-[Re (CO) 3-(bpy)(THF)](OTf), the starting material for 1. A was independently prepared and characterized (evidenced by 1HNMR, IR, and crystal structure) 1, 2 and shown to have an absorption spectrum close to that of 1 and to exhibit weak luminescence at∼ 580 nm, as initially reported for 2. A revised Figure 4 showing only the PL from 1 is given here, and Figure S-1 has been replaced in the revised Supporting Information to show the excitation spectrum of 1 only. These corrections do not change the conclusion of the published Communication that photoCORM 1 serves as a biocompatible, imageable reporter using PL to indicate the location of CO delivery in cellular media.

Page 18199. The quantum yield for the photosubstitution of 1 (see eq 1 in the original paper) in aerobic phosphatebuffered saline (10 mM, pH 7.4) under 365 nm irradiation was remeasured to be 0.024±0.001, roughly an order of magnitude smaller than previously reported, the higher value likely due to a computational or clerical error. The PL