Metal complexes of N-tosylamidoporphyrin: cis-acetato-N-tosylimido-meso-tetraphenylporphyrinatothallium(III) and trans-acetato-N-tosylimido-meso-tetraphenylporphyrinatogallium(III)

Insight into the mechanism and site-selectivity of Rh2II,II(esp)2-catalyzed intermolecular C–H amination

The mechanisms and site-selective determinants of Rh₂^II,II(esp)₂-catalyzed intermolecular C–H bond aminations of three isoamylbenzene-derived substrates, p-R–C₆H₄(CH₂)₂CH(CH₃)₂ (R = OCH₃, H, CF₃), have been investigated by the density functional theory (BPW91) method.

ESR, Zero-Field Splitting, and Magnetic Exchange of Exchange-Coupled Copper(II)−Copper(II) Pairs in Copper(II) Tetraphenylporphyrin N-Oxide

The crystal structures of the dimer form of copper(II) tetraphenylporphyrin N-oxide, [Cu(tpp-N-O)]2 (3-dimer), and zinc(II) tetraphenylporphyrin N-oxide, [Zn(tpp-N-O)]2 (4-dimer), were established. The geometry at the copper ion in 3-dimer is essentially square-pyramidal with one oxygen bridge [O(1A)] occupying the apical site, giving a much larger Cu-O bond distance compared to those at the basal plane. The respective Cu...Cu distance and Cu-O-Cu angle in the core of 3-dimer are 3.987(4) A and 148.1(3) degrees. The Zn(1) atom in 4-dimer has a distorted square-pyramidal [4 + 1] coordination geometry that gives a tau-value of 0.19. The respective Zn...Zn distance and Zn-O-Zn angle in the dimeric unit of 4-dimer are 4.025(3) A and 148.1(2) degrees. The 3-dimer displays axial X-band electron paramagnetic resonance spectral features (Es = 0) in the powder state at 4 K, giving g parallel = 2.51 (A(parallel,s) = (9.6 +/- 0.2) x 10-3 cm(-1)) and g(perpendicular) = 2.11 and in the same powder state at 293 K giving Ds = 0.0731 cm(-1) (as derived from DeltaMs = 1 lines) or 0.0743 cm(-1) (as derived from the DeltaMs = 2 lines). In addition, 3-dimer displays a DeltaMs = 2 transition at g = 4.17 indicating the presence of spin-exchange coupling. The anisotropic exchange interaction (Ds(ex)= 0.132 cm(-1)) gives the main contribution to Ds in 3-dimer. The theoretical fit of the susceptibility and effective magnetic moment data of 3-dimer in the temperature range of 5-300 K gives 2J = 68 cm(-1), g = 2.01, p = 0.06, and a temperature-independent paramagnetism of 10(-6) cm3 mol(-1). This magnetic susceptibility data indicates that the copper(II) ions in 3-dimer are coupled in a ferromagnetic manner with the ground-spin triplet stabilized by 68 cm(-1) with regard to the singlet.

Metal complexes of N-benzamidoporphyrin: (N-benzimido-meso-tetraphenylporphyrinato)(methanol)zinc(II) methanol solvate and (acetato)(N-benzamido-meso-tetraphenylporphyrinato)cadmium(II) benzene solvate

The crystal structures of N-benzamido-meso-tetraphenylporphyrin (NHCOC(6)H(5)-Htpp; 1), (N-benzimido-meso-tetraphenylporphyrinato)(methanol)zinc(II) [Zn(N-NCOC(6)H(5)-tpp)(MeOH); 2(MeOH)], and (acetato)(N-benzamido-meso-tetraphenylporphyrinato)cadmium(II) [Cd(N-NHCOC(6)H(5)-tpp)(OAc); 3] were established. The coordination sphere around Zn(2+) ion in 2(MeOH) is a distorted trigonal bipyramid with N(2), N(5), and O(2) lying in the equatorial plane, whereas, for Cd(2+) ion in 3, it is a sitting-atop derivative with a distorted trigonal bipyramidal geometry in which the apical site is occupied by atoms N(2) and O(2). Cd in 3 acquires five-coordination with five strong bonds [Cd(1)-N(1) = 2.319(5) A, Cd(1)-N(2) = 2.252(5) A, Cd(1)-N(3) = 2.332(5) A, Cd(1)-O(2) = 2.292(5) A, and Cd(1)-O(3) = 2.317(5) A] and with one secondary intramolecular interaction [Cd(1)...N(4)]. The porphyrin ring in these two complexes is distorted to a large extent. The plane of the three pyrrole nitrogen atoms [i.e., N(1)-N(3)] strongly bonded to Zn(2+) in 2(MeOH) and to Cd(2+) in 3 is adopted as a reference plane 3N. For the Zn(2+) complex, the pyrrole nitrogen bonded to the benzamido (BA) ligand lies in a plane with a dihedral angle of 33.8 degrees with respect to the 3N plane, but for the Cd(2+) complex, this dihedral angle is found to be 31.4 degrees. In the former complex, Zn(2+) and N(5) are located on the different side at -0.08 and 1.39 A from its 3N plane, and in the latter one, Cd(2+) and N(5) are also located on the different side at 1.08 and -1.51 A from its 3N plane. VT NMR ((1)H and (13)C) studies of 3 show that the acetate acts as a bidentate ligand and the OAc(-) exchange does not occur in CD(2)Cl(2). Moreover, the NH proton [i.e., H(5)] of 3 in CD(2)Cl(2) is observed as a sharp singlet at delta = -1.13 ppm with Delta nu(1/2) = 4 Hz at 20 degrees C indicating that the intermolecular proton exchange between water and NH proton is rapid.

Crystal and molecular structure of an eight-coodinate N-methyltetraphenylporphyrin complex: diacetato(N-methyl-meso-tetraphenylporphyrinato)thallium(III)

The crystal structure of diacetato(N-methyl-meso-tetraphenylporphyrinato)thallium(III), Tl(N-Me-tpp)(OAc)2 (1), was established, and the coordination sphere around the Tl3+ ion is described as an eight-coordinate square-based antiprism in which two cis chelating bidentate OAc- groups occupy two apical sites. The plane of the three pyrrole nitrogen atoms (i.e., N(1), N(3), N(4)) strongly bonded to Tl3+ is adopted as a reference plane 3N. The pyrrole N(2) ring bearing the methyl group (i.e., C(45)H3) is the most deviated one from the 3N plane, making a dihedral angle of 21.4 degrees, whereas smaller angles of 9.1 degrees, 7.1 degrees, and 0.9 degree occur with pyrroles N(1), N(3), and N(4), respectively. Because of its larger size, the thallium(III) ion Tl3+ is considerably out of the 3N plane; its displacement of 1.17 A is in the same direction as that of the two apical OAc- ligands. The intermolecular acetate exchange process for 1 in THF-d8 solvent is examined through 1H NMR temperature-dependent measurements. In the slow-exchange region, the methyl and carbonyl carbons of the OAc- groups in 1 are separately located at delta 18.6 [3J(Tl-13C) = 405 Hz] and 170.8 [2J(Tl-13C) = 334 Hz] at -80 degrees C, respectively.