Table 1.

Photocatalytic proton reduction experiments with various proton sources and sacrificial electron donors.^[a]

Entry	1⋅Fe4(Zn‐L)6, c [mm]	Proton source, c [mm]	SED [mm]	λ exc [nm]	H2 evolution
1[b]	0.08	TFA, 0.03	SED1, 0.2	590	yes
2[c]	0.08	TFA, 0.2	SED1, 0.8	590	no
3[d]	0.08	TFA, 0.2	SED1, 0.8	590	no
4[e]	0.08	TFA, 4.0	SED2, 20	590	no
5[e]	0.08	TFA, 0.03	SED3, 0.2	590	no
6	0.08	TFA, 0.03	SED4, 0.2	590	no
7[d]	0.08	TFA, 0.03	SED4, 1.7	590	no
8[e]	0.08	TFA, 0.8	SED5, 0.8	590	no
9[d,f]	0.08	H2O, excess	SED6, excess	590	no
10[e,g]	0.08	H2O, excess	SED6, excess	445	yes
11	0.08, catalyst 2+Fe4(Zn‐L)6	TFA, 0.03	SED1, 0.2	590	no

[a] Reactions were performed with deaerated acetonitrile solutions (5 mL) containing 1⋅Fe₄(Zn‐L)₆ formed in situ by mixing proton source and SED under continuous irradiation by 2.6 W LED lights. Irradiation time was 2 h and the reaction temperature was 298 K. An aliquot of the headspace was injected into a gas chromatograph by using a gastight syringe. [b] Further 0.4 equiv of TFA with respect to the catalyst was added after 1 h of irradiation, which resulted in more H₂ being formed. [c] SED self‐polymerizes and precipitates. [d] Decomposition of the cage was observed after precipitation of porphyrin building block. [e] Free CO was observed in the gas chromatogram owing to decomposition of the catalyst. [f] 5 % NEt₃ and CH₃CN:MilliQ H₂O (8.5:1) as solvent, proton source, and SED. [g] 0.5 % NEt₃ and CH₃CN:MilliQ water (99:1) as solvent, proton source and SED.