Exploring the Optimal Synthetic Pathways towards μ-Carbido Diruthenium(IV) Bisphthalocyaninates

Series of substituted mu-carbido diruthenium(IV) bisphthalocyaninates [Pc*Ru](2)(mu-C) [where Pc* = tetra-tert-butyl-, octa-n-butoxy-, tetra-15-crown-5- and hexa-n-butoxy-mono-(15-crown-5)-substituted ligands] were synthesized using two alternative approaches - (i) direct metalation of phthalocyanines with Ru-3(CO)(12) in refluxing o-dichlorobenzene where [Pc*Ru](2)(mu-C) are formed as by-products together with monomeric complexes [Pc*Ru](CO) and (ii) dimerization of [Pc*Ru](CO) by dichlorocarbene generated in situ from chloroform and bases (KOH or NMe4OH), which affords target complexes in high yield. Application of the appropriate base - NMe4OH was found to be crucial in the case of synthesis of crown-substituted mu-carbido dimers. Reaction of Ru-3(CO)(12) with the phthalocyanine bearing bulky mesityloxy-groups yielded solely monomeric complex which could not be dimerized under any studied conditions. Therefore, the influence of nature of peripheral substituents in phthalocyanines on their reactivity in metalation and dimerization reactions was revealed.