Nontemplate Syntheses of Complexes with Conjugated Macrocyclic Ligands

NONTEMPLATE SYNTHESES OF COMPLEXES WITH CONJUGATED MACROCYCLIC LIGANDS 

Submitted by COLIN LUCAS HONEYBOURNE and PAUL BURCHILL Checked by MYO K. YOO and GEORGE R. BRUBAKER  

Conjugated macrocyclic compounds play important roles in a number of important biological reactions and there has been a resurgence of interest in the electrical properties of such compounds. Although in both biochemical and semisuperconducting applications, side chains fulfill an important mechanistic role, the central conjugated ring is clearly essential. The compound 5,14-dihydrodibenzo[6,i] [1,4,8,11] tetraazacyclotetradecine (TADA-H2) is a suitable parent system for biochemical and electrical studies. There are problems with some published syntheses and physical properties.  

Propynal (HC CCHO) ( Caution. Propynal is a lachrymator, with a foul odor. An efficient fume hood must be used. o-Phenylenediamine (1,2-benzene-diamine j is toxic, and skin contact with the solid and inhalation either as vapor Or fine dust must be avoided) is prepared by standard methods but is used without first resorting to fractional distillation. o-Phenylenediamine is crystallized from water after purification with activated charcoal and sodium dithionite at 100° the diamine is sublimed before use. We strongly emphasize the care needed in diluting the propynal and that needed in adding a solution of the diamine. 

Cobalt(II) acetate tetrahydrate (1.89 g, 0.0075 mole) is dissolved in 30 mL of warm dimethylformamide, giving a purple solution. This is added to a stirred slurry of 1.81 g (0.0063 mole) of TADA-H2 in 20 mL of hot dimethylformamide. The resulting red-brown mixture is heated under gentle reflux for 30 minutes and cooled to room temperature before being placed in an ice-water bath. Filtration yields a light-red residue, wliich is retained, and a red-black fitrate, which is discarded. After washing with a large quantity of cold methanol, the sohd complex is dried in vacuo over silica gel. Yield 1.91 g (0.0055 mole. 

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Nontemplate Syntheses of Complexes with Conjugated Macrocyclic Ligands 45... 

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