Iron Complexes of 5,10,15,20-Tetraphenyl-21-oxaporphyrin

Abstract

The iron complexes of 5,10,15,20-tetraphenyl-21-oxaporphyrin (OTPP)H have been investigated. Insertion of iron(II) followed by one-electron oxidation yielded a high-spin, six-coordinate (OTPP)Fe(III)Cl(2) complex. The reduction of (OTPP)Fe(III)Cl(2) has been accomplished by means of moderate reducing reagents producing high-spin five-coordinate (OTPP)Fe(II)Cl. The molecular structure of (OTPP)Fe(III)Cl(2) has been determined by X-ray diffraction. The iron(III) 21-oxaporphyrin skeleton is essentially planar. The furan ring coordinates in the eta(1) fashion through the oxygen atom, which acquires trigonal geometry. The iron(III) apically coordinates two chloride ligands. Addition of potassium cyanide to a solution of (OTPP)Fe(III)Cl(2) in methanol-d(4) results in its conversion to a six-coordinate, low-spin complex [OTPP)Fe(III)(CN)(2)] which is spontaneously reduced to [OTPP)Fe(II)(CN)(2)](-) by excess cyanide. The spectroscopic features of [OTPP)Fe(III)(CN)(2)] correspond to the common low-spin iron(III) porphyrin (d(xy))(2)(d(xz)d(yz))(3) electronic configuration. Titration of (OTPP)Fe(III)Cl(2) or (OTPP)Fe(II)Cl with n-BuLi (toluene-d(8), 205 K) resulted in the formation of (OTPP)Fe(II)(CH(2)CH(2)CH(2)CH(3)). (OTPP)Fe(II)(n-Bu) decomposes via homolytic cleavage of the iron-carbon bond to produce (OTPP)Fe(I). The EPR spectrum (toluene-d(8), 77 K) is consistent with a (d(xy))(2)(d(xz))(2)(d(yz))(2)(d(z)(2)(1)(d[(x)(2)-(y)(2)])(0) ground electronic state of iron(I) oxaporphyrin (g(1) = 2.234, g(2) = 2.032, g(3) = 1.990). The (1)H NMR spectra of (OTPP)Fe(III)Cl(2), (OTPP)Fe(III)(CN)(2), ([(OTPP)Fe(III))](2)O)(2+), and (OTPP)Fe(II)Cl have been analyzed. There are considerable similarities in (1)H NMR properties within each iron(n) oxaporphyrin-iron(n) regular porphyrin or N-methylporphyrin pair (n = 2, 3). Contrary to this observation, the pattern of downfield positions of pyrrole resonances at 156.2, 126.5, 76.3 ppm and furan resonance at 161.4 ppm (273 K) detected for the two-electron reduction product of (OTPP)Fe(III)Cl(2) is unprecedented in the group of iron(I) porphyrins.

Developments in the metal chemistry of N-confused porphyrin

“…1b-d) [11] where the meso carbons are rearranged to form new macrocycle structures. The analogs of porphyrin are more diverse, and range from contracted , homophyrins (f), thiaporphyrins (g, X = S), and oxaporphyrins (g, X = O) [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27].…”

“…1e) [12][13][14][15][16][17][18][19], to expanded systems like the homophyrins (Fig. 1f) [20], and heteroatom substituted macrocycles, such as thiaporphyrins [21][22][23][24] and oxaporphyrins [25][26][27] (Fig. 1g).…”

Vibrational analysis of Ni(II) complex with 4,12-ditolyl-16,24-diphenyl-3-thiaporphyrin (SDTDPPNi(II)Cl) and its isotopic labeled (61Ni(II), −d6, and −d10) derivatives

“…[12], ν(C 72 -H 78 ) [14], ν(C 70 -H 79 ) [14], ν (C 43 -H 45 ) [12] , ν(C 42 -H 54 ) [14], ν(C 41 -H 55 ) [14] 0 0 0 3174 ν(C 74 -H 77 ) [12], ν(C 72 -H 78 ) [14], ν(C 70 -H 79 ) [14], ν(C 43 -H 45 ) [12], ν(C 42 -H 54 ) [14] , ν(C 41 -H 55 ) [14] 0 0 0 3172 ν(C 63 -H 66 ) [11], ν(C 62 -H 67 ) [16], ν(C 61 -H 68 ) [13], ν(C 50 -H 52 ) [11], ν(C 49 -H 59 ) [16], ν(C 48 -H 58 ) [13] 817 778-786 0 0 3171 ν(C 63 -H 66 ) [10], ν(C 62 -H 67 ) [16], ν(C 61 -H 68 ) [13], ν(C 50 -H 52 ) [10], ν(C 49 -H 59 ) [16], ν(C 48 -H 58 ) [13] 816 -1 -1 3163 ν(C 73 -H 76 ) [15], ν(C 70 -H 79 ) [21], ν(C 44 -H 53 ) [15], ν(C 41 -H 55 ) [21] 0 0 0 3163 ν(C 73 -H 76 ) [15], ν(C 70 -H 79 ) [21], ν(C 44 -H 53 ) [15], ν(C 41 -H 55 ) [21] 0 0 0 3158 ν(C 63 -H 66 ) [14], ν(C 61 -H 68 ) [10], ν(C 60 -H 69 ) [16], ν(C 50 -H 52 ) [14], ν(C 48 -H 58 ) [10], ν(C 47 -H 57 ) [16] 818 778-786 0 0 3158 ν(C 63 -H 66 ) [14], ν(C 61 -H 68 ) [10], ν(C 60 -H 69 ) [16], ν(C 50 -H 52 ) [14], ν(C 48 -H 58 ) …”

“…1032 ν(C 74 -C 73 ) [11], ν(C 72 -C 74 ) [12], ν(C 44 -C 43 ) [11], ν(C 42 -C 43 ) [12] 0 3 0 1021 1024 γ(C 74 -C 72 -C 73 -H 77 ) [14], γ(C 72 -C 70 -C 74 -H 78 ) [14], γ(C 43 -C 42 -C 44 -H 45 ) [14], γ(C 42 -C 43 -C 41 -H 54 ) [14] 0 0 0 1024 γ(C 74 -C 72 -C 73 -H 77 ) [14], γ(C 72 -C 70 -C 74 -H 78 ) [14], γ(C 43 -C 42 -C 44 -H 45 ) [14], γ(C 42 -C 43 -C 41 -H 54 ) [14] 0 0 0 1022 γ(C 50 -C 49 -C 46 -H 52 ) [10], γ(C 49 -C 48 -C 50 -H 59 ) [14], γ(C 48 -C 49 -C 47 -H 58 ) [12], γ(C 63 -C 62 -C 64 -H 66 ) [10], γ(C 62 -C 61 -C 63 -H 67 ) [14], γ(C 61 -C 60 -C 62 -H 68 ) [12] 93-105 179 0 0 1022 γ(C 50 -C 49 -C 46 -H 52 ) [10], γ(C 49 -C 48 -C 50 -H 59 ) [14], γ(C 48 -C 49 -C 47 -H 58 ) [13], γ(C 63 -C 62 -C 64 -H 66 ) [10], γ(C 62 -C 61 -C 63 -H 67 ) [14], γ(C 61 -C 60 -C 62 -H 68 ) [13] 179 0 0 1017 δ 1 (Phe III ) [17], δ 1 (Phe IV ) [ 1007 γ(C 71 -C 5 -C 73 -H 75 ) [12], γ(C 73 -C 71 -C 74 -H 76 ) [13], γ(C 70 -C 5 -C 72 -H 79 ) [11], γ(C 40 -C 27 -C 44 -H 56 ) [12], γ(C 44 -C 43 -C 40 -H 53 ) [13], γ(C 41 -C 27 -C 42 -H 55 ) [11] 0 0 0 1007 γ(C 71 -C 5 -C 73 -H 75 ) [12], γ(C 73 -C 71 -C 74 -H 76 ) [13], γ(C 70 -C 5 -C 72 -H 79 ) [11], γ(C 40 -C 27 -C 44 -H 56 ) [12], γ(C 44 -C 43 -C 40 -H 53 ) [13], γ(C 41 -C 27 -C 42 -H 55 ) [11] 0 0 0 1006 γ(C 46 -C 34 -C 50 -H 51 ) …”

From 21,23‐Dioxaporphyrin to a 3‐Pyranone Dioxacorrole Skeleton: The Achmatowicz Rearrangement in the Porphyrin Frame

“…Widely defined porphyrinoids suit as a unique environment that allows observing a specific metal-carbon interaction (carbaporphyrinoids) [13] or stabilization of a less abundant oxidation states of transition metals (hetero-porphyrinoids). [10,14] The studies which address the profound rearrangement of the separate heterocycle (carbocycle) entrapped in the porphyrinoid are rather rare and limited to a few examples. [15] Here, we report on an unprecedented route of the Achmatowicz rearrangement which is encompassed within the 5, 10,15,20-tetratolyl-21,23-dioxaporphyrin frame, leading to a 3-pyranone dioxacorrole skeleton.…”