syn 1‐Periplanar Bisazo Skeletons — Syntheses and Reactions with Carbonylmetal Complexes

Preparatively useful synthesis for the novel, relatively mobile polycyclic syn 1‐periplanar bisazo polycycles 4 and 5 are based on hydrazine condensation with readily available dienedione 6 and acid‐catalyzed rearrangement of bisurazole 12 , respectively. In the preferred “closed” and “open” conformations of 4 and 5 the NN bonds are 314 and 496 pm, respectively, apart (MMX). From the reactions of 4 and 5 with carbonyliron and ‐ruthenium compounds, complexes are derived which are typical of monoazo ligands [ 4 · Fe(CO) 4 20, 4 · Fe 2 (CO) 7 21, 4 · Fe 3 (CO) 9 22, 4 [Fe 2 (CO) 6 ] 2 23, 4 · Ru 3 (CO) 9 · 24, 5 · [Fe 2 (CO) 6 ] 2 25, 5 · Fe 2 (CO) 6 · Fe 3 (CO) 9 26 ]. For 21, 23 and 26 crystal structure analyses were performed, confirming i.a. in 26 the unique presence of a Fe 2 (CO) 6 and a Fe 3 (CO) 9 fragment attached to two azo units of the same molecule.