Re(CO)₃-Templated Synthesis of α-Amidinoazadi(benzopyrro)methenes

Abstract

α-amidino azadi(benzopyrro)methenes were synthesized using the Re(CO)3 unit as a templating agent. The products of these template reactions are six-coordinate Re complexes, with a facial arrangement of carbonyls, a non-coordinating anion, and a tridentate α-amidino azadi(benzopyrro)methene ligand. The tridentate ligand shows the conversion of one diiminoisoindoline sp2 carbon to a sp3 carbon which has been seen in the “helmet” and bicyclic phthalocyanines. The bidentate diiminoisoindoline fragment tilts out of the plane of coordination. Five examples of α-amidino azadi(benzopyrro)methenes were produced from these reactions using different nitrile solvents, including the nitrile activation of acetonitrile, propionitrile, butyronitrile, cyclohexanecarbonitrile, and benzonitrile were formed.

Pyrazole and Indazole Semihemiporphyrazine Complexes of Rhenium Tricarbonyl: A Structure/Properties Study

“…These pyridine compounds were also fully characterized and show the expected 1 H resonances and stretching frequencies in their NMR and IR spectra respectively. [8,11] We were able to crystallographically characterize most of the semihemiporphyrazine complexes of Re(CO) 3 ; the only exceptions were the oxo terminated compounds 3 a and 3 b, which formed highly twinned crystals that were unsuitable for diffraction. The Re(CO) 3 X structures are shown in Figure 3, while the pyridine substituted Re(CO) 3 compounds are displayed in Figure 4.…”

“…We were also able to replace the halides in these compounds with a pyridine ligand in the 6 th position via reaction of the chloride variant with AgPF 6 in acetonitrile, as also shown in Scheme 1. These pyridine compounds were also fully characterized and show the expected 1 H resonances and stretching frequencies in their NMR and IR spectra respectively [8,11] …”

“…[7] In our investigations into new diimine ligand structures, we have been inspired by the phthalocyanine and porphyrazine classes of macrocycles. We have recently investigated both halfphthalocyanine and half-hemiporphyrazine type ligands, [8][9][10] with the latter class of chelates known as semihemiporphyrazines. [11] Frequently, these types of bidentate chelates are not stable in the absence of a metal ion template designed to prevent macrocycle formation.…”

Tricarbonylrhenium(I) Complexes with Tridentate Schiff Bases

“…Potentially tridentate Schiff bases become interesting, since they can match the available coordination positions of the {M(CO) 3 } + cores (M = Re, Tc) and, thus, provide a maximum of stability for the corresponding complexes [14–27] . Such a stability, preferably accompanied by a kinetic inertness, is a fundamental requirement for use of corresponding tricarbonyl complexes in nuclear medical applications.…”

1,3-Diylideneisoindolines: Synthesis, Structure, Redox, and Optical Properties

“…1,3-Diiminoisoindoline (DII, Scheme ) has long been an important reagent for the synthesis of chelates and chromophores. − First introduced by Linstead in early 1950s and produced by the reaction of ammonia with phthalonitrile, DII can be used to synthesize phthalocyanines as well the hemiporphyrazines, bis­(arylimino)­isoindoline chelates, and related chromophores. − One of the most common types of reactivity observed with DII is the formation of Schiff bases upon exposure to primary amines, which is exemplified in the hemiporphyrazines and bis­(arylimino)­indoline ligands. However, the DII unit can potentially undergo a variety of chemical reactions to potentiate its use as a building block for a variety of structural motifs.…”