Synthesis, Crystal Structure, DNA Binding, and Hydrolytic Cleavage Activity of a Manganese(II) Complex

A new trinuclear manganese(II) complex {[MnCl(bpma)](2)[Mn(n-Cl)(4)(H2O)(2)]}center dot CH3CN (1) [bpma = N,N-bis(2-pyridylmethyl)methylamine] has been synthesized and structurally characterized by X-ray crystallography. The variable temperature-dependent susceptibility measurement (2300 K) of 1 reveals a weak antiferromagnetic interaction between the manganese ions through the dichlorido bridging ligands, with J = -0.46 cm(-1), g = 1.99. The electrospray ionization mass spectrum of 1 in solution indicates that the dinuclear [Mn-2(bpma)(2)Cl-2(H2O)(OH)](+) ion is the active species. In the absence of a reducing agent, supercoiled plasmid DNA cleavage by the active species was performed and its hydrolytic mechanism was demonstrated with radical scavengers, anaerobic reaction, and T4 ligase. The pseudo-Michaelis-Menten kinetic parameters (k(cat), K-M) were calculated to be 1.11 h(-1) and 6.65 x 10(-4) M for the dinuclear species.