SOLITAIRE-PORPHYRAZINES - SYNTHETIC, STRUCTURAL, AND SPECTROSCOPIC INVESTIGATION OF COMPLEXES OF THE NOVEL BINUCLEATING NORPHTHALOCYANINE-2,3-DITHIOLATO LIGAND

We have developed the synthesis of unsymmetrical metalloporphyrazines of the form M[pz(A:B-3)], where A and B refer to two different types o f peripheral functionality, and have used it to prepare new bi- and tr imetallic solitaire-porphyrazines in which A represents a mono- or bim etallic moiety. The macrocyclic complexes described are based on the b inucleating ligand, [M(norphthalocyanine-2,3-dithiolate)](2-), [M(norp c)](2-). This can be thought of as a metalloporphyrazine when B is a f used benzo ring; A represents two thiolates fused at the beta-pyrrole positions to form a dithiolene moiety that can bind a transition-metal ion in addition to one within the macrocyclic cavity. solitaire-Porph yrazines have been synthesized by chelation of [(L-L)M'](2+) to the [M (norpc)](2-) ligand where M = ''2H'', Ni, Cu, or Mn-CI, L-L is a bis(d iphosphino) or bis(diamino) group and M' = Ni, Pd, or Pt. Crystal stru ctures have been obtained for 11b, where the [H-2(norpc)](2-) ligand c oordinates the diphosphinopalladium moiety, [Pd-(dppf)](2+), by the tw o thiolate sulfur atoms at its periphery, and for 11h, with the diamin oplatinum moiety, [Pt-(teeda)](2+), bound to the periphery of the [Ni( norpc)](2-) ligand. In crystals of 11b and 11h, the molecules appear a s face-to-face dimers. However, the dimer of 11b and the two crystallo graphically independent dimers of 11h each shows a distinctly differen t degree of overlap. The electronic absorption spectra of a series of porphyrazines in which the two peripheral sulfur atoms form thioether moieties with a modified benzyl-protecting group (6-10) show that the peripheral asymmetry of the macrocyclic framework causes a strong spli tting of the (pi-pi) Q-band. In contrast, when the peripheral sulfurs bind a metal ion to form solitaire-porphyrazines 11a-h, the optical s pectra closely resemble that of the symmetrical pc, with unsplit Q ban d. The EPR spectrum of solitaire lid, where M = Cu, L-L = a bis(diphos phino) cap, M' = Pd, has features consistent with other square-planar copper(II) porphyrins and phthalocyanines. Cyclic voltammograms of com pound 11b shows two reversible ring reductions at potentials similar t o those of H-2(pc) as well as a reversible oxidation associated with t he ferrocene portion of the Pd(dppf) moiety.