Molecular and Electronic Structure of [Mn^VN(cyclam−acetato)]PF₆. A Combined Experimental and DFT Study

From the reaction of Li(cyclam-acetate), MnCl(2).4H(2)O, and KPF(6) in methanol brown microcrystals of [Mn(III)Cl(cyclam-acetato)]PF(6) (1) were obtained in the presence of air (cyclam-acetic acid = 1,4,8,11-tetraazacyclotetradecane-1-acetic acid). The reaction of 1 in aqueous NH(3) solution with NaOCl produced blue crystals of [Mn(V)N(cyclam-acetato)]PF(6) (2). Complexes 1 and 2 were characterized by single-crystal X-ray crystallography, IR and Raman, electronic absorption, and (1)H, (13)C, and (15)N NMR spectroscopies. Their magnetochemistry as well as their electrochemistry have been investigated. The complexes [MnN(cyclam-acetato)](+/2+) were studied by theoretical calculations at the DFT and semiempirical levels in order to obtain more insight into the ground and excited states of the Mn(V)(triple bond)N unit. Structural and spectroscopic parameters were successfully calculated and compared to experiment. A pictorial description of the bonding has been developed.