Crystalline salts of the ring-reduced tin(IV) dichloride hexadecachlorophthalocyanine and octachloro- and octacyanotetrapyrazinoporphyrazine macrocycles with strong electron-withdrawing ability

Abstract

Substituted tin(IV) dichloride phthalocyanine and tetrapyrazinoporphyrazines with acceptor chloro- or cyano-substituents: SnIVCl2(PcCl16), SnIVCl2(TPyzPzCl8) and SnIVCl2{TPyzPz(CN)8}, where PcCl16 = hexadecachlorophthalocyanine; TPyzPz(CN)8 = octacyanotetrapyrazinoporphyrazine, TPyzPzCl8 = octachlorotetrapyrazinoporphyrazine were synthesized. The reduction of these metallomacrocycles by fullerene {cryptand(Na+)}(C60•−) salt (1, 3 and 4) or potassim graphite (KC8) in the presence of cryptand (2) yields crystalline anionic salts: {cryptand(Na+)}2[SnIVCl2(PcCl164−)]2−⋅C6H4Cl2 (1), {cryptand(K+)}2[{SnII(PcCl164−)}0.926{SnIVCl2(PcCl164−)}0.074]2−⋅2C6H4Cl2 (2), {cryptand(Na+)}[SnIVCl2{TPyzPz(CN)8•3−}]•−⋅C6H4Cl2 (3) and {cryptand(Na+)}2[SnIVCl2(TPyzPzCl84−)]2−⋅2C6H4Cl2 (4). Reduction of SnIVCl2(macrocycle2−) with dianion macrocycles is accompanied by the formation of radical trianion or tetraanion macrocycles in 1–4. As stronger reductant, KC8 reduces the macrocycle and in addition nearly complete metal centered reduction from tin(IV) to tin(II) took place. Strong blue shift of the Q-band and new absorption bands are observed in the NIR range in the spectra of 1–4. Partial disruption of macrocycle aromaticity and alternation of the C – Nmeso bonds were found for the reduced macrocycles. Macrocycles are planar, and SnIV atoms are positioned exactly in the macrocycle plane. The only exception is strong distortion of the PcCl16 macrocycle in SnII(PcCl164−) (2). Structures of 1–4 contain layers from the macrocycles having the side-by-side contacts in 1, 2, 4 and separated by cationic layers. Salt 3 presents the first structure of the TPyzPz(CN)8 macrocycle with strongest acceptor properties amomg known porphyrins and porphyrazines. It was shown that tetraanion macrocycles are diamagnetic in 1, 2 and 4. The [SnIVCl2{TPyzPz(CN)8)•3−}]•− radical anions are paramagnetic in 3 with effective magnetic moment of 1.64 μB, and salt 3 shows moderate antiferromagnetic coupling of spins with Weiss temperature of −14 K.