William S. Durfee

The synthesis and structure of mixed complexes

Abstract The template cyclization of tetrafluorophthalonitrile (A) and 2,3-naphthalenedicarbonitrile (B) with BCl 3 produces two mixed subphthalocyanine subnaphthalocynine complexes of the form A 2 B and AB 2 . Over the series A 3 , A 2 B, AB 2 and B 3 the Q-band λ max shifts 100 nm: 573 (A 3 ), 617 (A 2 B), 640 (AB 2 ), 673 nm (B 3 ). An X-ray crystal structure of the A 2 B complex has been determined.

Synthesis and characterization of lithium hemiporphyrazines.

The hemiporphyrazines comprise a broad class of phthalocyanine analogues where one or two of the diiminoisoindolene units are replaced with alternative rings, including pyridines, benzenes, and azoles. As a means to explore the fundamental metal chemistry of these macrocycles, we have prepared the first lithium complexes of three hemiporphyrazine variants: the common bis-pyridine ring, the bis-benzene macrocycle (also known as dicarbahemiporphyrazine), and the monobenzene variant (also known as benziphthalocyanine). The metal cation can be inserted via reaction of the free bases by using lithium bis(trimethylsilyl)amide, and the resulting products all form 1:1 complexes with protonation at the meso nitrogens providing charge balance. For the two carbahemiporphyrazines studied, the internal C-H bond remains intact upon metalation. Similar structures have been observed in the transition metal complexes of the carbaporphyrins. In addition, all three complexes are characterized by (7)Li solid state NMR and by cyclic voltammetry.

The metal chemistry of the carbahemiporphyrazines

Over fifty years ago, Linstead and Elvidge described the syntheses of phthalocyanine-like macrocycles in which one or two of the interior metal-binding nitrogen atoms were replaced with aromatic C-H groups. We review here the coordination chemistry of two of these systems, dicarbahemiporphyrazine and benziphthalocyanine, and we emphasize the unusual reactivity displayed by these macrocycles and the varying extent to which the C-H groups are activated by metal-binding.

The structures of free-base carbahemiporphyrazines

In this report we present an X-ray crystallographic study of two N-deficient hemiporphyrazines: dicarbahemiporphyrazine (1) and benziphthalocyanine (2). Both compounds can be isolated in multiple crystal forms, and five different solvated forms of macrocycle 1 are presented. Four of the five are non-planar, showing the high degree of flexibility and capacity for hydrogen bonding from solvent to N-H groups in the macrocycle. The remaining structure of 1 is a planar dicationic species that represents a tautomeric form of the macrocycle often seen in metal binding. Four structures of macrocycle 2 are also presented in this report. The structure of 2 is also planar due to the tautomerism of the internal protons, and structural elucidation of this macrocycle reveals the presence of three ionizable protons rather than the expected single proton postulated by Elvidge and Golden.

MCD spectroscopy and TD-DFT calculations of low symmetry subnaphthalocyanine analogs.

Magnetic circular dichroism (MCD) spectroscopy and time-dependent density functional theory (TD-DFT) calculations are used to analyze the electronic structure and optical properties of low-symmetry subnaphthalocyanine analogs with AAB and ABB structures formed during mixed condensations of tetrafluorophthalonitrile and 2,3-naphthalenedicarbonitrile. The results demonstrate that trends observed in the properties of phthalocyanine analogs can be used to fine tune the optical properties so that the Q(0,0) bands lie in the red region, in a manner that does not significantly destabilize the highest occupied molecular orbital (HOMO) energy relative to that of the parent subphthalocyanine ligand. Attempts to study the spectroscopy of anion radical species proved unsuccessful, since they proved to be unstable.

The influence of strong and weak hydrogen bonds on the solid state arrangement of hydroxy-containing boron subphthalocyanines

We have investigated the occurrence of hydrogen bonding in boron subphthalocyanine (BsubPc) derivatives by synthesizing a series of four hydroxy-containing BsubPcs and studying their solid state arrangements using X-ray diffraction. The series of derivatives comprises hydroxy-BsubPc (HO-BsubPc) as well as para-, meta-, and ortho-hydroxy-phenoxy-BsubPc (p-, m- and o-HOPhO-BsubPc). Each solid state arrangement demonstrated both strong (O–H⋯N, O–H⋯O) and weak (C–H⋯O, C–H⋯N) hydrogen bonds, with the structure for o-HOPhO-BsubPc including examples of bifurcated hydrogen bonds. Many of the C–H⋯O interactions were found to occur alongside notable perturbations to the expected intra- and intermolecular geometry of BsubPcs, providing structural evidence for the significance of weak C–H⋯O bonds. We observed that the imine nitrogen atom of the BsubPc moiety is a reliable hydrogen bond acceptor, and in most arrangements, the hydroxy moiety participated in hydrogen bonds both as a donor and an acceptor. The presence of hydrogen bonds in addition to other intermolecular interactions (π–π and CH–π, which are common in BsubPc solid state arrangements) facilitates the arrangement of BsubPc into two- and three-dimensional networks of closely associated molecules.

Hydroxybenziphthalocyanines: non-aromatic phthalocyanine analogues that exhibit strong UV-visible absorptions

The hemiporphyrazine variants hydroxybenziphthalocyanine and dihydroxybenziphthalocyanine can be generated via sequential Schiff base condensation reactions by using bis(diiminoisoindoline) benzene intermediates. These compounds are not aromatic due to the lack of conjugation across the benzene rings, yet these macrocycles exhibit striking absorption bands in the low energy region of the UV-visible spectrum.

Co(II) and Co(III) complexes of m-benziphthalocyanine

The syntheses and structural elucidations of three different cobalt complexes of m-benziphthalocyanine are reported; both Co(II) and Co(III) complexes can be generated, and the ring undergoes partial oxidation upon metalation with Co(OAc)2x4H2O.

Quinone-functionalized Transition Metal Complexes for Multi-electron Transfer. The Electrochemistry of a Bis -Naphthoquinone-Functionalized Schiff Base Ni(II) complex

Ni(II)NQ 2 en, a Ni(II) complex with two naphthoquinone groups incorporated into a Schiff-base ligand, undergoes two reversible reductions in which the naphthoquinone (NQ) groups are each reduced by one electron to naphthsemiquinone radical anions (SQ):