An All-O-Donor Family of Mn(II) and Mn(III) Complexes with Perfluorinated Alkoxide Ligands

Complexes of Mn with exclusively O-donor ligands are quite rare. Herein are five new Mn complexes supported by perfluoropinacolate (pinF)2– or perfluoro-tert-butoxide (OC4F9)1– ligands: Me4N[Mn(OH2)(pinF)2]·MeOH·H2O, 1·MeOH·H2O; K(18C6)[Mn(THF)(pinF)2]·2 THF, 2·2 THF; K4[Mn2(μ2-CO3)(pinF)4]·4 H2O· MTBE (methyl t-butyl ether), 3·4 H2O· MTBE; K2[Mn(O2CtBu)(pinF)2]·2 MTBE, 4·2 MTBE; K2[Mn(O2CH)(pinF)2]·MTBE, 5·2 MTBE; and K(18C6)[Mn(OC4F9)3], 6. These compounds have been characterized by UV–vis spectroscopy, the Evans method for magnetic susceptibility, and SCXRD. Compounds 1–3 and 5 have been characterized by high-field EPR (HFEPR), along with the previously reported K[Mn(OH2)(pinF)2], 7, K2[Mn(OAc)(pinF)2], 8, and K(18C6)[Mn(pinF)2], 10. Complex 3 was characterized by variable-temperature magnetic susceptibility (SQUID) measurements. Complex 4 is formed from the nucleophilic attack of the previously reported {Mn(III)OH} complex K2[Mn(OH)(pinF)2]·3 MTBE, 9, on pivaloyl chloride (tBuC(O)Cl). This reactivity represents the first example of a nucleophilic attack by a structurally characterized {Mn(III)OH} complex. Electronic structure calculations corroborate the high-spin assignments for Mn(III) complexes 2, 5, 7–10, and were used to assign transitions in each electronic absorption spectrum. Excellently resolved HFEPR spectra were observed for 2, and 5 - 10, allowing accurate determination of the spin Hamiltonian parameters. Crystallographically independent molecules could be resolved in 7 and 8. Solvent loss in powder samples of 2 and 5 was evident in HFEPR.