A phosphorus supported multisite coordinating tris hydrazone P(S)[N(Me)N=CH-C6H4-o-OH]3 as an efficient ligand for the assembly of trinuclear metal complexes: Synthesis, structure, and magnetism

A phosphorus supported multisite coordinating ligand P(S)[N(Me)N=CH-C 6H4-o-OH]3 (2) was prepared by the condensation of the phosphorus tris hydrazide P(S)[N(Me)NH2] 3 (1) with o-hydroxybenzaldehyde. The reaction of 2 with M(OAc) 2·xH2O (M = Mn, Co, Ni, x = 4; M = Zn, x = 2) afforded neutral trinuclear complexes {P(S)[N(Me)N=CH-C6H 4-o-O]3}2M3 [M = Mn (3), Co (4), Ni (5), and Zn (6)]. The X-ray crystal structures of compounds 2-6 have been determined. The structures of 3-6 reveal that the trinculear metal assemblies are nearly linear. The two terminal metal ions in a given assembly have an N3O3 ligand environment in a distorted octahedral geometry while the central metal ion has an O6 ligand environment also in a slightly distorted octahedral geometry. In all the complexes, ligand 2 coordinates to the metal ions through three imino nitrogens and three phenolate oxygens; the latter act as bridging ligands to connect the terminal and central metal ions. The compounds 2-6 also show intermolecular C-H⋯S=P contacts in the solid-state which lead to the formation of polymeric supramolecular architectures. The observed magnetic data for the (s = 5/2)3 L2(Mn(II))3 derivative, 3, show an antiferromagnetic nearest- and next-nearest-neighbor exchange (J = -4.0 K and J′ = -0.15 K; using the spin Hamiltonian ĤHDvV = -2J(Ŝ1Ŝ2 + Ŝ2Ŝ 3) - 2J′Ŝ1Ŝ3). In contrast, the (s = 1)3 L2(Ni(II))3 derivative, 5, displays ferromagnetic nearest-neighbor and antiferromagnetic next-nearest-neighbor exchange interactions (J = 4.43 K and J′ = -0.28 K; Ĥ = ĤHDvV + Ŝ1DŜ1 + Ŝ2DŜ2 + Ŝ3DŜ 3). The magnetic behavior of the L2(Co(II))3 derivative, 4, reveals only antiferromagnetic exchange analogous to 3 (J = -4.5, J′ = -1.4; same Hamiltonian as for 3).