1,2-Cyclobutanedione, 3,4-bis(3,5-bis(1,1-dimethylethyl)-4-oxo-2,5-cyclohexadien-1-ylidene)- 3,4-Bis(3,5-bis(1,1-dimethylethyl)-4-oxo-2,5-cyclohexadien-1-ylidene)-1,2-cyclobutanedione 61377-19-3