.beta.-Halogenated-pyrrole porphyrins. Molecular structures of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetramesitylporphyrin, nickel(II) 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetramesitylporphyrin, and nickel(II) 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(pentafluorophenyl)porphyrin

Abstract

The X-ray structures of the 8-substituted-pyrrole tetraarylporphyrin 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetramesitylporphyrin (H2TMOBP), its nickel(I1) complex (NiTMOBP), and the nickel(I1) derivative of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20tetrakis(pentafluoropheny1)porphyrin (NiTPFPOBP.1/2CH2C1z) are reported. The synthesis of the free base H,TPFPOBP is also described. All these molecules are nonplanar, displaying saddle-shaped conformations. The saddle distortions minimize the intramolecular steric interactions between the bromine substituents and the ortho (ortho') carbon atoms or ortho (ortho') substituents of the phenyl rings, and consequently, the corresponding contact distances have similar values in all compounds. Because of the distortion of the porphyrin cores, the cavity defined by the ortho (ortho') substituents gives slightly less steric protection than in the nonbrominated nearly planar ortho-and ortho'-substituted tetraarylporphyrin complexes. Crystallographic data: C56H4sN4Brs (H2TMOBP), tetragonal, space group P42,c, a = b = 15.085 (4) A, c = 14.056 (4) A, V = 3198.8 A', Z = 2, RF = 0.054, RwF = 0.069 based on 638 reflections with I > 3a(10), T = 298 K; NiC56H44N4Brs,1s (NiTMOBP), tetragonal, space group P421c, a = b = 15.024 (3) A, c = 14.068 (6) 1, V = 3175.2 A', Z = 2, RF = 0.049, R w F = 0.057 based on 877 reflections with lo > 2.5u(10), T = 298 K; NiCMN4F2 BrsJ/2CH2C12 (NiTPFPOBP-1/2CH2C1z), monoclinic, space group C2/c, a = 18.105 (3) A, b = 22.141 (5) A, c = 24.301 ( 5 ) 1, B = 93.32 (2)O, V = 9725.5 A', Z = 8, RF = 0.047, RwF = 0.064 based on 2896 reflections with Io > 3a(10), T = 298 K.

Bromination of porphyrins (Review)

“…of N-bromosuccinimide in boiling chloroform [67]. The authors of [49,52,53,57,92] also reached their own conclusion in favour of N-bromosuccinimide during the production of octabromotetraarylporphyrinates [93]. Here such parameters as the solvent, rate of addition of the reagents, and reaction time were varied.…”

3,12-Dinitro-5,10,15,20-tetraphenylporphyrin – an example of a twisted intramolecular charge-transfer system

“…The displacements of the meso C atoms, C5, C10, C15 and C20 from the mean N4 plane are -0.15 (1), -0.03 (1), -0.02 (1) and 0.21 (1)A, respectively. These distortions lead to a saddle conformation of the porphyrinoid skeleton similar to those observed for pyrrole-substituted tetraphenyl porphyrins (Bhyrappa, Nethaji & Krishnan, 1993;Mandon et al, 1992). The inner imino H atoms are positioned trans to each other on the pyrrole rings not bearing the nitro groups with N--H distances of 1.10 (9) and 0.96 (9) A (Silvers & Tulinsky, 1967;Chen & Tulinsky, 1971).…”

“…Moreover, tetraphenyl porphyrins bearing substitutents at the pyrrole C atoms exhibit interesting conformational features 1991; Barkigia et al, 1990;Mandon et al, 1992). Details of the synthetic work will be published elsewhere (Dahal & Krishnan, 1993).…”

Coordination compounds of cobalt porphyrins with nitrogen monoxide

“…The simulta neous introduction of eight bromine atoms into the β positions of the pyrrole rings and four benzene residues into the meso positions of the macrocycle of porphyrin 2 changes the effective charge on the reaction center due to the electron withdrawing effect of Br and also consider ably distorts the planar structure of the aromatic ligand. 24 This also favors a decrease in the stability of the axial complexes of porphyrin 2 with NO and NO 2 -compared to the complexes of compounds 1, 3, and 4 having a planar structure of the macrocycle. The decrease in К of the nitrite complexes compared to the nitrosyl complexes for all systems under study indicates the predominantly electrostatic character of the Co-NO 2 bond.…”