Design, syntheses, crystal structures and magnetic properties of a series of cyanide-bridged heterometallic Cr(III)-Mn(III) one-dimensional complexes

Six new cyanide-bridged Cr-III-Mn-III one-dimensional (1D) complexes [Mn-III(salen)Cr-III(bpb)(CN)(2)](n) (1), [Mn-III(5-Clsalen)Cr-III(bpb)(CN)(2)center dot 0.5CH(3)OH center dot H2O](n) (2), [Mn-III(5-Brsalen)Cr-III(bpb)(CN)(2)center dot 0.5CH(3)OH.H2O](n) (3), [Mn-III(5-MeOsalen)Cr-III(bpb)(CN)(2)center dot H2O](n), (4), [Mn-III(5-Clsalen)Cr-III(bpCIb)(CN)(2)center dot CH3CN](n) (5) and. [MNIII(5-Brsalen)Cr-III(bpClb)(CN)(2) 2H(2)O](n) (6) have been rationally designed, controlling synthesized and structurally characterized based on [Mn-III(5-R(1)salen)](+) and [Cr-III(4-R(2)bpb)(CN)(2)](-)building blocks [5-R(1)salen(2)-=N,N'-ethylenebis(5-R-1-salicylideneaminato)dianion, R-1= H for salen(2-), Cl for 5-Clsalen(2-), Br for 5-Brsalen(2)-and MeO for 5-MeOsalen(2-); 4-R(2)bpb(2-)= 1,2-bis(pyridine-2-carboxamido)-4-R-2-benzenate, R-2 = H for bpb(2)-and Cl for bpC1b(2-)]. The single crystal structures of these complexes consist of alternating units of [Mn-III(5-Risalen)](+) and [Cr-III(4-R(2)bPb)(CN)(2)](-), forming cyanide-bridged neutral 1D complexes. Investigation over magnetic properties of these complexes reveals the whole relatively weak antiferromagnetic interactions between Mn(III) ion and Cr(III) through cyanide bridge. The magnetic susceptibilities of these complexes were fitted based on the suitable 1D Cr-III-M-III magnetic model. The magneto-structural correlation for cyanide-bridged Cr-III-Mn-III systems reveals that the cyanide-bridging bond angle is related to the magnitude of magnetic exchange coupling: the larger the Mn-N C bond angle, the weaker antiferromagnetic interactions. (C) 2016 Elsevier B.V. All rights reserved.