Two double end-on cyanato-bridged dinuclear manganese(II) complexes exhibiting abnormal magnetic coupling for the Mn(II)–N–Mn(II) linkage

Two cyanato-bridged dinuclear Mn(II) complexes [Mn 2 (phen) 4 ( μ 1,1 -NCO) 2 ][M III (bpb)(CN) 2 ]·H 2 O [M = Fe ( 1 ) or Co ( 2 )], [phen = 1,10-phenanthroline, bpb 2− = 1,2-bis(pyridine-2-carboxamido)benzenate] have been synthesized using the synthetic strategy of big anion inducement. Single-crystal X-ray diffraction analysis reveals that both complexes consist of a double end-on (EO) cyanato-bridged dinuclear Mn(II) unit and two free [M(bpb)(CN) 2 ] − building blocks acting as counter-ions. Magnetic studies show the presence of abnormal antiferromagnetic interactions between the two Mn(II) centers through the EO cyanate bridge with J = −1.58(3) cm −1 for complex 1 and −1.82(2) cm −1 for complex 2 . The unusual antiferromagnetic interactions of these complexes can be attributed to their small Mn(II)–N–Mn(II) angles.