Regioisomer‐Free C 4 h β‐Tetrakis( tert ‐butyl)metallo‐phthalocyanines: Regioselective Synthesis and Spectral Investigations

Metal β‐tetrakis( tert ‐butyl)phthalocyanines are the most commonly used phthalocyanines due to their high solubility, stability, and accessibility. They are commonly used as a mixture of four regioisomers, which arise due to the tert ‐butyl substituent on the β‐position, and to the best of our knowledge, their regioselective synthesis has yet to be reported. Herein, the C 4 h ‐selective synthesis of β‐tetrakis( tert ‐butyl)metallophthalocyanines is disclosed. Using tetramerization of α‐trialkylsilyl phthalonitriles with metal salts following acid‐mediated desilylation, the desired metallophthalocyanines were obtained in good yields. Upon investigation of regioisomer‐free zinc β‐tetrakis( tert ‐butyl)phthalocyanine using spectroscopy, the C 4 h single isomer described here was found to be distinct in the solid state to zinc β‐tetrakis( tert ‐butyl)phthalocyanine obtained by a conventional method.