I cannot find out what the role of molybdate is in the synthesis of phthalocyanine.
From research, I know it is needed for the conversion isocyanic acid (resulting from decomposition of urea ..source (need to use universtity server to access)) and phthalimide to 1,3-diiminoisoindoline. The source says 1-amino-3-iminoisoindoline but
that would result after the reduction of the previous compound.