Unique outcomes have emerged from the redox transmetallation/ protolysis (RTP) reactions of europium metal with [Ag(C₆F₅)(py)] (py=pyridine) and pyrazoles (RR′pzH). In pyridine, a solvent not normally used for RTP reactions, the products were mainly Eu^II complexes, [Eu(RR′pz)₂(py)₄] (RR′pz=3,5‐diphenylpyrazolate (Ph₂pz) 1; 3‐(2‐thienyl)‐5‐trifluoromethylpyrazolate (ttfpz) 2; 3‐methyl‐5‐phenylpyrazolate (PhMepz) 3). However, use of 3,5‐di‐tert‐butylpyrazole (tBu₂pzH) gave trivalent [Eu(tBu₂pz)₃(py)₂] 4, whereas the bulkier N,N′‐bis(2,6‐difluorophenyl)formamidine (DFFormH) gave divalent [Eu(DFForm)₂(py)₃] 5. In tetrahydrofuran (thf), the usual solvent for RTP reactions, C−F activation was observed for the first time with [Ag(C₆F₅)(py)] in such reactions. Thus trivalent [{Eu₂(Ph₂pz)₄(py)₄(thf)₂(μ‐F)₂}{Eu₂(Ph₂pz)₄(py)₂(thf)₄(μ‐F)₂}] (6), [Eu₂(ttfpz)₄(py)₂(dme)₂(μ‐F)₂] (7), [Eu₂(tBu₂pz)₄(dme)₂(μ‐F)₂] (8) were obtained from the appropriate pyrazoles, the last two after crystallization from 1,2‐dimethoxyethane (dme). Surprisingly 3,5‐dimethylpyrazole (Me₂pzH) gave the divalent cage [Eu₆(Me₂pz)₁₀(thf)₆(μ‐F)₂] (9). This has a compact ovoid core held together by bridging fluoride, thf, and pyrazolate ligands, the last including the rare μ₄‐1η⁵(N₂C₃): 2η²(N,N′): 3κ(N): 4κ(N′) pyrazolate binding mode. With the bulky N,N′‐bis(2,6‐diisopropylphenyl)formamidine (DippFormH), which often favours C−F activation in RTP reactions, neither oxidation to Eu^III nor C−F activation was observed and [Eu(DippForm)₂(thf)₂] (10) was isolated. By contrast, Eu reacted with Bi(C₆F₅)₃ and Ph₂pzH or tBu₂pzH in thf without C−F activation, to give [Eu(Ph₂pz)₂(thf)₄] (11) and [Eu(tBu₂pz)₃(thf)₂] (12) respectively, the oxidation state outcomes corresponding to that for use of [Ag(C₆F₅)(py)] in pyridine.

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