Ruthenium compound, process for producing same, process for producing ruthenium-containing thin film using same, and ruthenium-containing thin film

(2,4-Dimethylpentadienyl)(ethylcyclopentadienyl)ruthenium from which a ruthenium-containing thin film can be produced even when the compound contains an analogous compound; a process for producing the ruthenium compound; a process for producing a ruthenium-containing thin film using said compound; and a ruthenium-containing thin film.  An analogous compound is separated from (2,4-dimethylpentadienyl)(ethylcyclopenta­dienyl)ruthenium containing the analogous compound to thereby obtain (2,4-dimethylpentadienyl)(ethylcyclopentadienyl)­ruthenium in which the content of the analogous compound is 5 wt.% or lower.  This ruthenium compound is used as a raw material to produce a thin film.