Mono- and bis-phosphine-ligated H93G myoglobin: Spectral models for ferrous-phosphine and ferrous-CO cytochrome P450

Ferric/ferrous tris(hydroxymethyl)phosphine (THMP)-H93G myoglobin (Mb) complexes having THMP/X (X = none, THMP, imidazole, CO and O2) heme axial ligand(s) have been prepared and examined here with UV-visible and magnetic circular dichroism (MCD) spectroscopy. Interestingly, THMP/CO- (shown here, a hyperporphyrin) and bis-THMP-bound ferrous H93G Mb exhibited P450-type UV-Vis and MCD spectra.