Multinuclear paramagnetic NMR spectra and solid state X-ray crystallographic characterization of manganese(III) Schiff-base complexes

The H-1 NMR spectra of symmetrically substituted paramagnetic [(R,R'-SALOPHEN)Mn-III](+) and [(R,R'-SALOPHEN)Mn-III](2)(mu-O) complexes (SALOPHEN is 1,3-bis(salicylideneamino)benzene) were obtained. All of the monomers and dimers yielded well-resolved but isotropically shifted H-1 NMR spectra. A diamagnetic suppression routine was applied to the H-1 NMR spectra that allowed observation of all rapidly relaxing resonances. The binding of axial ligands, acetate, methanol, water, and pyridine was also observable by H-1 NMR. Two X-ray crystal structures were obtained: [(3,3'-17-crown-6-SALOPHEN)Mn-III].(CH3C(O)O). BaTf2 . 2H(2)O, [9b]-OAc . OAc . BaTf2 . 2H(2)O, crystallized in the triclinic space group P (1) over bar; with a = 10.747(2) Angstrom, b = 12.271(8) Angstrom, c = 16.206(6) Angstrom, alpha = 106.10(4)degrees, beta = 103.07(2)degrees, gamma = 106.06(3), and Z = 2, while [(3,3',6,6'-(CH3)(4)-SALOPHEN)-Mn-III]PF6 . H2O, [6b]PF6 . H2O, crystallized in the monoclinic space group P2(1)/n, with a = 12.465(1) Angstrom, b = 13.366(2) Angstrom, c = 15.240(1) Angstrom, beta = 103.051(7)degrees, and Z = 2. [9b]OAc . BaTf2 . 2H(2)O has the Mn(III) center ligated in the axial positions by one oxygen of the acetate group and an oxygen from one SO3CF3-. The second oxygen of the acetate is bound to the Ba2+ residing in the crown ether. The water molecule in [6b]PF6 . H2O is O-bound to the Mn(III) center and also hydrogen bonded to one of the fluorine atoms of the PF6 counterion, O-F 3.01 Angstrom. H-1 and F-19 NMR spectra revealed that the hydrogen bond in [6b]PF6 . H2O was preserved in CD3OD.