Nonperipheral Tetrakis(dibutylamino)phthalocyanines. New Types of 1,8,15,22-Tetrakis(substituted)phthalocyanine Isomers

Cyclic tetramerization of 3-(dibutylamino)­phthalonitrile in refluxing n-pentanol in the presence of magnesium pentanoate afforded the four regioisomer-containing nonperipheral 1,8-/11,15-/18,22-/25-tetrakis­(dibutylamino)­phthalocyaninato magnesium complexes with the 1,8,15,22-tetrakis­(dibutylamino)­phthalocyanine isomer Mg­{Pc­[α-N­(C₄H₉)₂]₄-C₄} (2). This, in combination with its much superior crystallinity over the remaining three isomers, renders the easy isolation of 2 only through two simple recrystallizations from THF and methanol. Treatment of 2 with trifluoroacetic acid induced the isolation of metal-free 1,8,15,22-tetrakis­(dibutylamino)­phthalocyanine, H₂{Pc­[α-N­(C₄H₉)₂]₄-C₄} (1), which further reacted with M­(OAc)₂·nH₂O (M = Ni, Zn) in refluxing n-pentanol, giving the 1,8,15,22-tetrakis­(dibutylamino)­phthalocyaninato metal complexes M­{Pc­[α-N­(C₄H₉)₂]₄-C₄} (M = Ni (3), Zn (4)). The full series of four 1,8,15,22-tetrakis­(dibutylamino)­phthalocyanine isomeric compounds have been characterized by a series of spectroscopic methods and single-crystal X-ray diffraction analyses. Obviously, the present result provides a simple and effective pathway for the synthesis and isolation of novel 1,8,15,22-tetrakis­(dibutylamino)­phthalocyanine isomeric derivatives, providing one step forward toward completing bis­(alkyl)­amino-incorporated phthalocyanine species.