Rapid and Simple Isolation of the Crystalline Molybdenum‐Blue Compounds with Discrete and Linked Nanosized Ring‐Shaped Anions: Na ₁₅ [MoMoO ₄₆₂ H ₁₄ (H ₂ O) ₇₀ ] _0.5 [MoMoO ₄₅₇ H ₁₄ (H ₂ O) ₆₈ ] _0.5 · ca. 400 H ₂ O and Na ₂₂ [MoMoO ₄₄₂ H ₁₄ (H ₂ O) ₅₈ ] · ca. 250 H ₂ O