| The complexes [(Me3TACN)2Mn(II)2(OAc) 3]BPh4 (1) (Me3TACN = N,N ′,N′′-trimethyl-1,4,7-triazacyclononane; OAc = acetates1−; BPh4 = tetraphenylborates 1−) and (NEt3)2[Mn(II)2(salmp) 2] (2) (salmp = 2-(bis(salicylideneamino)methyl)phenolate 3−) were studied with EPR spectroscopy at X- and Q-band frequencies, for both perpendicular and parallel polarizations of the microwave field, and with variable temperature (2–50 K). These spectra were simulated by diagonalization of the full spin Hamiltonian. The simulations are quantitative, allowing for the first time the determination of species concentrations directly from EPR spectra.; Manganese catalase was purified from Lactobacillus plantarum and found to have low active site metal occupation (23%) as isolated. A determination of the exchange coupling constant for the reduced protein gave J = −5 ± 0.5 cm−1 (Hex = −2JS 1·S2). An eleven-line signal with line-spacings of 2.8 mT at g = 16 in the parallel mode X-band EPR spectrum is attributed to the S = 4 manifold of a ferromagnetically coupled Mn(III)Mn(III) state of the active site of the protein.; The complex Mn(III)SALOPHEN (SALOPHEN = 1,3-bis(salicylideneamino(benzene))) was studied with parallel polarization X-band EPR spectroscopy. The simulation of these spectra using a full spin Hamiltonian is presented for spectra in two solvents. A value for the axial zero-field splitting parameter was determined as D = −1 to −2 cm−1. Solvent molecules were observed to coordinate to the Mn(III) ion in the axial positions, where the coordination of CH3CN broadens the six-line hyperfine pattern due to a superhyperfine interaction with the coordinated nitrogen atom (14N, I = 1).; We report the isolation and structural characterization of an Fe(II) complex containing a trigonal monopyramidal coordination geometry, [Fe 1iPr]− (H31 iPr = tris-(N-isopropylcarbamoylmethyl)amine) and the five coordinate complex [Fe1iPr(CO)] − formed upon CO binding. [Fe1iPr] − is a high spin Fe(II) (S = 2) complex, while [Fe1iPr(CO)]− is a low spin Fe(II) (trigonal bipyramidal) S = 1 complex, as demonstrated by the magnetic moments, EPR and Mössbauer spectra of the complexes.; A series of non-heme {lcub}Fe-NO{rcub}7 complexes with trigonal bipyramidal coordination geometry were synthesized with tripodal ligands derived from tris(N-R-carbamoylmethy)amine [1 R]3− (R = isopropyl (iPr), cyclopentyl (cyp), or 3,5-dimethylphenyl (dmp) groups). The complexes differ in their Fe-N-O angles which range from 178.2(5)° in [Fe1 iPr(NO)]− to 160.3(2)° in [Fe 1dmp(NO)]−. This angular difference is supported by EPR measurements which show that [Fe1 dmp(NO)]− has a significantly more rhombic spectrum than that found for [Fe1iPr(NO)] −. Magnetic moment, Mössbauer and... |
