Abstract: Anew tailed iron( Ⅱ )porphyrin complex mcso-MDBPTPPFe( Ⅱ ), with a tailed Et₂N-as axial base,reacts with nitric oxide to form adduct meso-MDBPTPPFe( Ⅱ ) NO. The N-Ostretching frequency for this adduct is 1671cm^-1. Spectral results demonstrate that when meso-MDBPTPPFe( Ⅱ ) is coordinated by NOin the sixth coordination position the axial coordinated base is away from iron because the unpaired electron of NOhas to go into the antibonding orbital of sp³(N) + d_z²(Fe). The observed three g values in meso-MDBPTPPFe( Ⅱ )NO EPRspectrum indicate that the d_xz and d_yz orbitals are nondegenerate and the iron-nitric oxide unite is bent.