The iClick Reaction of a BODIPY Platinum(II) Azido Complex with Electron-Poor Alkynes Provides Triazolate Complexes with Good 1O2 Sensitization Efficiency

trans-[Pt­(bodipy)­(N3)­(PEt3)2] (bodipy = 4,4-difluoro-4-bora-3a,4a-diaza-s-indacen-8-yl; Et = ethyl) reacts with dimethyl acetylenedicarboxylate (DMAD) or F3C–C≡C–COOEt in a catalyst-free room-temperature iClick reaction to provide the complexes [Pt­(bodipy)­(triazolateR,R′)­(PEt3)2] with R = R′ = COOCH3 or R = CF3, R′ = COOEt. The main product is the N2-coordinated triazolate, but some minor signals point to an additional N1 species as well as some trans → cis isomerization of the Pt­(PEt3)2 moiety. Kinetic studies with 1H, 19F, and 31P NMR spectroscopy gave second-order rate constants k2 in the range of (2.5–6.0) × 10–3 M–1 s–1, with the CF3-substituted alkyne reacting faster than DMAD. Upon photoexcitation, the parent azido complex as well as the two triazolate products exhibit considerable efficiency in the triplet-state population. Notably, the efficiency of intersystem crossing was modulated by the iClick reaction, which was also studied by density functional theory calculations.