The η1-H-CHg agostic interactions in the mercury complexes of N-confused porphyrin.

Six four-coordinated complexes of the chemical formulae [Hg(2-N CH2COOCH2CH3-21-H-NCTPP)X] with X = Cl (5), Br (6), I (7), [Hg(2-NCH3-21-H-NCTPP)Cl] (4) and [Hg(2-NCH2COOCH2C6H5-21-H-NCTPP)X] with X = Cl (8), I (9) are synthesized and structurally determined. The bond path for the weak η1-H(17)-C(17)Hg agostic interactions between the Hg center and H(17) in complexes 4-9 was a through-space interaction from Hg to agostic carbon [C(17)] followed by a through-bond interaction from C(17) to an agostic proton [H(17)]. The magnitude of J[Hg-H(17)] [or the agostic upfield shift Δδago of the C(17)] for these complexes increases as the halide ligand varies from iodide to chloride, ranging from 33.2 Hz (or 14.3 ppm) for I- to 36 Hz (or 15.8 ppm) for Br- and 36.9 Hz (or 16.0 ppm) for Cl-. The plot of J[Hg-H(17)] for the agostic proton H(17) versus |Δδago| for the agostic carbon atom C(17) in compounds 3-9 was linearly expressed as J[Hg-H(17)] = 2.29 |Δδago| + 0.13.

Axial zero-field splitting in mononuclear Co(ii) 2-N substituted N-confused porphyrin: Co(2-NC3H5-21-Y-CH2C6H4CH3-NCTPP)Cl (Y = o, m, p) and Co(2-NC3H5-21-CH2C6H5-NCTPP)Cl.

The inner C-benzyl- and C-o-xylyl (or m-xylyl, p-xylyl)-substituted cobalt(ii) complexes of a 2-N-substituted N-confused porphyrin were synthesized from the reaction of 2-NC3H5NCTPPH (1) and CoCl2·6H2O in toluene (or o-xylene, m-xylene, p-xylene). The crystal structures of diamagnetic chloro(2-aza-2-allyl-5,10,15,20-tetraphenyl-21-hydrogen-21-carbaporphyrinato-N,N',N'')zinc(ii) [Zn(2-NC3H5-21-H-NCTPP)Cl; 3 ] and paramagnetic chloro(2-aza-2-allyl-5,10,15,20-tetraphenyl-21-benzyl-21-carbaporphyrinato-N,N',N'')cobalt(ii) [Co(2-NC3H5-21-CH2C6H5NCTPP)Cl; 7], and chloro(2-aza-2-allyl-5,10,15,20-tetraphenyl-21-Y-xylyl-21-carbaporphyrinato-N,N',N'')cobalt(ii) [Co(2-NC3H5-21-Y-CH2C6H4CH3NCTPP)Cl] [Y = o (8), m (9), p (10)] were determined. The coordination sphere around the Zn(2+) (or Co(2+)) ion in 3 (or 7-10) is a distorted tetrahedron (DT). The free energy of activation at the coalescence temperature Tc for the exchange of phenyl ortho protons o-H (26) with o-H (22) in 3 in a CDCl3 solvent is found to be ΔG = 61.4 kJ mol(-1) through (1)H NMR temperature-dependent measurements. The axial zero-field splitting parameter |D| was found to vary from 35.6 cm(-1) in 7 (or 30.7 cm(-1) in 8) to 42.0 cm(-1) in 9 and 46.9 cm(-1) in 10 through paramagnetic susceptibility measurements. The magnitude of |D| can be related to the coordination sphere at the cobalt sites.

Unusual inner C-alkylation of 2-N-substituted N-confused porphyrin cobalt complexes in toluene and p-xylene.

The inner C-benzyl- and C-p-xylyl-substituted cobalt(II) complexes of a 2-N-substituted N-confused porphyrin were synthesized from the reaction of 2-NCH2COOCH2C6H5NCTPPH (1) and CoCl2·6H2O in toluene (or p-xylene), and the structures were revealed by single-crystal X-ray analysis.

A 13C and 1H NMR spectroscopic investigation of the structure of the iminium ion with a dipolar form in metal complexes of 2-N-substituted N-confused porphyrins.

The crystal structures of chloro(2-aza-2-ethoxycarbonylmethyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N'N'') zinc(II) [Zn(2-NCH2COOC2H5NCTPP)Cl; 4], (2-aza-2-ethoxycarbonylmethyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N'N'') palladium(II) [Pd(2-NCH2COOC2H5NCTPP); 5], bromo(2-aza-2-ethoxycarbonylmethyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N'N'') manganese(III) [Mn(2-NCH2COOC2H5NCTPP)Br; 6], [2-aza-(3'-phenoxypropyl)-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N'N''] nickel(II) [Ni(2-NCH2CH2CH2OC6H5NCTPP); 7] and chloro(2-aza-2-methoxycarbonylmethyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N'N'') zinc(II) [Zn(2-NCH2COOCH3NCTPP)Cl; 8] have been established. The g value of 9.54, which was measured from the parallel polarization of the X-band EPR spectra in CHCl3 at 4 K, is consistent with the high spin mononuclear manganese(III) centre (S = 2) in 6. The magnitude of the axial (D) zero-field splitting (ZFS) for the mononuclear Mn(III) centre in 6 was determined approximately to be 1.63 cm(−1) by paramagnetic susceptibility measurements. The NMR spectroscopic investigation of the iminium ion with a dipolar canonical contribution to the metal complexes 5­7, Pd(2-NCH2C6H5NCTPP) (10) and Ni(2-NCH2C6H5NCTPP) (11) in CDCl3 is reported. A resonance between the dipolar canonical form II and covalent canonical form I exists for complexes 5­7, 10 and 11 in CDCl3. To develop the correlations between δ13C [C(3)], δ1H [H(3)] and the canonical form II in 5­7, 10 and 11, this work thoroughly examines the 13C and 1H NMR of N+=CH(Ar) fragment on seven metal complexes of 2-N substituted N-confused porphyrin. According to these results, the 13C [C(3)] and 1H [H(3)] chemical shifts of the N+=CH(Ar) fragment at 20 °C in CDCl3 are separately located at 152.6 ± 0.5 and 8.30 ± 0.15 ppm respectively for the iminium ion. This exists as a dipolar canonical form II for complexes 5­7, 10 and 11, and the N­CH(Ar) group appears at 121.1 ± 0.1 ppm and 6.35 ± 0.01 ppm, which is in a covalent canonical form I contribution to complexes 4 and 8. X-Ray diffraction data indicate that N(2)­C(3) = 1.315 ± 0.011 Å for the dipolar contribution of 5­7, 10­13, while N(2)­C(3) = 1.331 ± 0.008 Å for the covalent contribution of 4 and 8.

Intermediate (S = 1) spin state in five-coordinate cobalt(III): magnetic properties of N-o-hydroxy-benzamido-meso-tetraphenylporphyrin cobalt(III), Co(N-NCO(o-O)C6H4-tpp).

The crystal structures of paramagnetic N-o-oxido-benzimido-meso-tetraphenylporphyrinato (-kappa(4),N(1),N(2),N(3),N(5),kappaO(2))cobalt(III) [Co(N-NCO(o-O)C(6)H(4)-tpp); 2] (S = 1) and diamagnetic N-o-oxido-benzimido-meso-tetraphenylporphyrinato (-kappa(4),N(1),N(2),N(3),N(5),kappaO(2)) gallium(III) chloroform.methanol solvate [Ga(N-NCO(o-O)C(6)H(4)-tpp).0.5CHCl(3).MeOH; 3.0.5CHCl(3).MeOH] (S = 0) were determined. The coordination sphere around Co(III) in 2 [or Ga(III) in 3.0.5CHCl(3).MeOH] is described as five-coordinate distorted trigonal bipyramid (DTBP) with O(1), N(1) and N(3) [or O(2), N(1), N(3)] lying in the equatorial plane for 2 [or 3.0.5CHCl(3).MeOH]. The magnitude of axial (D) zero-field splitting (ZFS) for the Co(III) (S = 1) in 2 was determined as approximately 107 cm(-1) by paramagnetic susceptibility measurements. The compound (2) reacts in donor solvent such as pyridine to form six-coordinate diamagnetic species of the type Co(N-NCO(o-O)C(6)H(4)-tpp)(py) (4), whose (1)H NMR spectra can be interpreted as for Co(III) in an octahedral environment.

Magnetic susceptibility and ground-state zero-field splitting in high-spin mononuclear manganese(III) of inverted N-methylated porphyrin complexes: Mn(2-NCH3NCTPP)Br.

The crystal structures of diamagnetic dichloro(2-aza-2-methyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N',N'')-tin(IV) methanol solvate [Sn(2-NCH 3NCTPP)Cl 2.2(0.2MeOH); 6.2(0.2MeOH)] and paramagnetic bromo(2-aza-2-methyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N',N'')-manganese(III) [Mn(2-NCH 3NCTPP)Br; 5] were determined. The coordination sphere around Sn (4+) in 6.2(0.2MeOH) is described as six-coordinate octahedron ( OC-6) in which the apical site is occupied by two transoid Cl (-) ligands, whereas for the Mn (3+) ion in 5, it is a five-coordinate square pyramid ( SPY-5) in which the unidentate Br (-) ligand occupies the axial site. The g value of 9.19 (or 10.4) measured from the parallel polarization (or perpendicular polarization) of X-band EPR spectra at 4 K is consistent with a high spin mononuclear manganese(III) ( S = 2) in 5. The magnitude of axial ( D) and rhombic ( E) zero-field splitting (ZFS) for the mononuclear Mn(III) in 5 were determined approximately as -2.4 cm (-1) and -0.0013 cm (-1), respectively, by paramagnetic susceptibility measurements and conventional EPR spectroscopy. Owing to weak C(45)-H(45A)...Br(1) hydrogen bonds, the mononuclear Mn(III) neutral molecules of 5 are arranged in a one-dimensional network. A weak Mn(III)...Mn(III) ferromagnetic interaction ( J = 0.56 cm (-1)) operates via a [Mn(1)-C(2)-C(1)-N(4)-C(45)-H(45A)...Br(1)-Mn(1)] superexchange pathway in complex 5.

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.