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

作者：Chang Wen Pin; Lin Wen Chain; Chen Jyh Horung^*; Wang Shin Shin; Tung Jo Yu

来源：Dalton Transactions, 2012, 41(43): 13454-13464.

DOI：10.1039/c2dt31426f

The crystal structures of chloro(2-aza-2-ethoxycarbonylmethyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato- N, N%26apos; N %26apos;%26apos;) zinc(II) [Zn(2-NCH2COOC2H5NCTPP) Cl; 4], (2-aza-2-ethoxycarbonylmethyl- 5,10,15,20-tetraphenyl-21-carbaporphyrinato-N, N%26apos; N %26apos;%26apos;) palladium(II) [Pd(2-NCH2COOC2H5NCTPP); 5], bromo(2-aza-2-ethoxycarbonylmethyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N, N%26apos; N %26apos;%26apos;) manganese(III) [Mn(2-NCH2COOC2H5NCTPP) Br; 6], [2-aza-(3%26apos;-phenoxypropyl)-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N, N%26apos; N %26apos;%26apos;] nickel(II) [Ni(2-NCH2CH2CH2OC6H5NCTPP); 7] and chloro(2-aza-2-methoxycarbonylmethyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N, N%26apos; N %26apos;%26apos;) 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 5-7, 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 5-7, 10 and 11 in CDCl3. To develop the correlations between delta C-13 [C(3)], delta H-1 [H(3)] and the canonical form II in 5-7, 10 and 11, this work thoroughly examines the C-13 and H-1 NMR of N+ = CH(Ar) fragment on seven metal complexes of 2-N substituted N-confused porphyrin. According to these results, the C-13 [C(3)] and H-1 [H(3)] chemical shifts of the N+ = CH(Ar) fragment at 20 degrees 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 5-7, 10 and 11, and the N-CH(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 angstrom for the dipolar contribution of 5-7, 10-13, while N(2)-C(3) = 1.331 +/- 0.008 angstrom for the covalent contribution of 4 and 8.

• 出版日期2012