TY - JOUR
T1 - Pitfalls in bromination reactions of zinc porphyrins
T2 - Two-sided ring opening of the porphyrin macrocycle
AU - Nandi, Goutam
AU - Titi, Hatem M.
AU - Goldberg, Israel
PY - 2014/8/4
Y1 - 2014/8/4
N2 - Reaction of [ZnII(TTP)] (1) (TTP = dianion of 5,10,15,20-meso-tetrakis(p-tolyl)porphyrin) with 16 equiv of N-bromosuccinamide (NBS) in methanol at reflux led to the unexpected two-sidedd open-ring brominated product [ZnII(C26H20N 2O2Br5)2] (2). Similar observations have been made with other meso-substituted zinc porphyrins as well [Zn II(por)] {por = dianion of 5,10,15,20-meso-tetrakis(aryl)porphyrin; aryl = phenyl (TPP), p-tBu-phenyl (TBPP), m-Cl-phenyl (TClPP)}. The respective products [ZnII(C24H16N 2O2Br5)2] (3), [Zn II(C32H32N2O2Br 5)2] (4), and [ZnII(C24H 14N2O2Cl2Br5) 2] (5) have been isolated in good to moderate yields and characterized by elemental analysis and UV-vis, 1H NMR, and mass spectrometry. Additional bromination reaction of 1 with 8 equiv of NBS in a chloroform/methanol mixture led (after the two-sided ring opening) to nonmetalated brominated bi(pyrrole) product, C36H34N 2O4Br4 (6). The detailed structures of complexes 1, 2, 3, and 6, available in a single crystal form, have been confirmed by X-ray diffraction analysis.
AB - Reaction of [ZnII(TTP)] (1) (TTP = dianion of 5,10,15,20-meso-tetrakis(p-tolyl)porphyrin) with 16 equiv of N-bromosuccinamide (NBS) in methanol at reflux led to the unexpected two-sidedd open-ring brominated product [ZnII(C26H20N 2O2Br5)2] (2). Similar observations have been made with other meso-substituted zinc porphyrins as well [Zn II(por)] {por = dianion of 5,10,15,20-meso-tetrakis(aryl)porphyrin; aryl = phenyl (TPP), p-tBu-phenyl (TBPP), m-Cl-phenyl (TClPP)}. The respective products [ZnII(C24H16N 2O2Br5)2] (3), [Zn II(C32H32N2O2Br 5)2] (4), and [ZnII(C24H 14N2O2Cl2Br5) 2] (5) have been isolated in good to moderate yields and characterized by elemental analysis and UV-vis, 1H NMR, and mass spectrometry. Additional bromination reaction of 1 with 8 equiv of NBS in a chloroform/methanol mixture led (after the two-sided ring opening) to nonmetalated brominated bi(pyrrole) product, C36H34N 2O4Br4 (6). The detailed structures of complexes 1, 2, 3, and 6, available in a single crystal form, have been confirmed by X-ray diffraction analysis.
UR - http://www.scopus.com/inward/record.url?scp=84905454363&partnerID=8YFLogxK
U2 - 10.1021/ic500468r
DO - 10.1021/ic500468r
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AN - SCOPUS:84905454363
SN - 0020-1669
VL - 53
SP - 7894
EP - 7900
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 15
ER -