Coupling ferrocene to brominated tetraazaporphyrin: exploring an alternative synthetic pathway for preparation of ferrocene-containing tetraazaporphyrins

Authors : Victor N NEMYKIN, Elena A MAKAROVA, Nathan R ERICKSON, Pavlo V SOLNTSEV

Pages : 1027-1045

Doi:10.3906/kim-1406-19

View : 14 | Download : 7

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :A Castro--Stephens coupling reaction between metal-free 3insert ignore into journalissuearticles values(2);,8insert ignore into journalissuearticles values(7);-dibromo- 2insert ignore into journalissuearticles values(3);,7insert ignore into journalissuearticles values(8);,12insert ignore into journalissuearticles values(13);,17insert ignore into journalissuearticles values(18);-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin and insert ignore into journalissuearticles values(ferrocenylethynyl);copper resulted in the formation of copper 2insert ignore into journalissuearticles values(3);,7insert ignore into journalissuearticles values(8);,12insert ignore into journalissuearticles values(13);, 17insert ignore into journalissuearticles values(18);-tetra-tert-butyl-3insert ignore into journalissuearticles values(2);, 8insert ignore into journalissuearticles values(7);-diinsert ignore into journalissuearticles values(ferrocenylethynyl);-5,10,15,20-tetraazaporphyrin and copper 2insert ignore into journalissuearticles values(3);,7insert ignore into journalissuearticles values(8);,12insert ignore into journalissuearticles values(13);,17insert ignore into journalissuearticles values(18);-tetra-tert-butyl-3insert ignore into journalissuearticles values(2);-ferrocenylethynyl-5, 10,15,20-tetraazaporphyrin, which were separated in the form of 2 positional isomers along with copper 3insert ignore into journalissuearticles values(2);-bromo-2insert ignore into journalissuearticles values(3);,7insert ignore into journalissuearticles values(8);,12insert ignore into journalissuearticles values(13);,17insert ignore into journalissuearticles values(18);-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin and copper 2insert ignore into journalissuearticles values(3);,7insert ignore into journalissuearticles values(8);,12insert ignore into journalissuearticles values(13);,17insert ignore into journalissuearticles values(18);-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin. A similar reaction with metal-free 3insert ignore into journalissuearticles values(2);,8insert ignore into journalissuearticles values(7);,13insert ignore into journalissuearticles values(12);, 18insert ignore into journalissuearticles values(17);-tetrabromo-2insert ignore into journalissuearticles values(3);,7insert ignore into journalissuearticles values(8);,12insert ignore into journalissuearticles values(13);,17insert ignore into journalissuearticles values(18);-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin resulted in only a trace amount of 3insert ignore into journalissuearticles values(2);,8insert ignore into journalissuearticles values(7);,13insert ignore into journalissuearticles values(12);-tribromo-2insert ignore into journalissuearticles values(3);,7insert ignore into journalissuearticles values(8);,12insert ignore into journalissuearticles values(13);,17insert ignore into journalissuearticles values(18);-tetra-tert-butyl-18insert ignore into journalissuearticles values(17); -ferrocenylethynyl-5,10,15,20-tetraazaporphyrin, while no products with larger number of organometallic substituents were observed. Direct coupling between ferrocenelithium and 3insert ignore into journalissuearticles values(2);,8insert ignore into journalissuearticles values(7);-dibromo-2insert ignore into journalissuearticles values(3);,7insert ignore into journalissuearticles values(8);,12insert ignore into journalissuearticles values(13);,17insert ignore into journalissuearticles values(18);-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin resulted in a debromination reaction accompanied by very minor dimerization of the tetraazaporphyrin core, which was explained based on the steric properties of the parent tetraazaporphyrin. The target compounds were characterized using APCI mass spectrometry, UV-vis, and MCD spectroscopy, while the electronic structure of ferrocenylethyl-containing products was predicted by DFT approach. X-ray structures of individual positional isomers of copper 2-bromo-3,7,12,18-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin and 3, 7, 12,18-tetrabromo-2,8,13,17-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin were also discussed.
Keywords : Ferrocene, tetraazaporphyrin, coupling reaction, magnetic circular dichroism, UV vis spectra, density functional theory