Fig. 2. Usage of precursors in solid-state synthesis.

(A) Fraction of targets that can be synthesized with limited number of available precursors. The precursors are ordered by relative frequency per metal/metalloid element. Precursors for 62 elements are considered. A target is included if at least one reported reaction for that target was performed with the available precursors. (B) Pairwise dependency of precursors A_i and B_i characterized by $\frac{P(A_i,B_i)}{P(A_i)P(B_i)}$. Probability is estimated from the frequency of occurrence in the solid-state synthesis dataset. The value of ${\log }_{10}\frac{P(A_i,B_i)}{P(A_i)P(B_i)}$ is zero when A_i and B_i are independent, positive when A_i and B_i tends to be used in the same experiment more frequently than P(A_i)P(B_i), negative otherwise.