Synthesis, Structure, and Stereochemistry of Trinuclear Metal Complexes Formed from the Phosphorus-Based Achiral Tripodal Ligand P(S)[N(Me)N=CHC6H4-o-OH]3 (LH3): Luminescent Properties of L2Cd32H2O

Neutral trinuclear metal complexes L2Cd3\ue22H2O, L2Mn3\ue2MeOH, and L2Zn3\ue2MeOH were isolated in the reaction between the phosphorus-centered achiral tris(hydrazone) P(S)[N(Me)NdCHC6H4-o-OH]3 (LH3) and the corresponding divalent metal ions. The trinuclear complexes contain two equivalent terminal metal ions (Mt) and a central metal ion (Mc). The ligand encapsulates Mt in a facial N3O3 coordination environment. From the coordination sphere of the two terminal metal ions a pair of phenolic oxygen atoms further coordinate to the central metal ion. The coordination requirements of Mc are completed by the solvents of coordination. The achiral trianionic tripodal ligand (L)3- induces chirality in the metal complexes. This results in a \ua2 (clockwise) or \ua4 (anticlockwise) configuration for the terminal metal ions. The enantiomeric complexes 2-4 (\ua2-\ua2 or \ua4-\ua4) crystallize as racemic compounds. The supramolecular structures of 2-4 reveal chiral recognition in the solid-state; every molecule with the \ua2-\ua2 configuration interacts stereospecifically, through C-H\ue2\ue2\ue2SdP bonds, with two \ua4-\ua4 molecules to generate a one-dimensional polymeric chain. Photophysical studies of the diamagnetic trinuclear complexes reveal that the tricadmium complex is luminescent in the solid state as well as in solution. In contrast LH3 and L2Zn3\ue2MeOH are nonluminescent

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)

Latvijas Ūniversitātes Raksti. Ķīmijas fakultātes serija. 4.sēj., No.6

The unprecedented transformation of a terminal two-electron-donor amidinate–germylene ligand into a chelating three-electron-donor κ²-<i>N,Ge</i>-imine–germanate ligand has been achieved by treating the manganese amidinate–germylene complex [MnBr­{Ge­(^<i>i</i>Pr₂bzam)^<i>t</i>Bu}­(CO)₄] (<b>1</b>; ^<i>i</i>Pr₂bzam = <i>N</i>,<i>N</i>′-bis­(isopropyl)­benzamidinate) with LiMe or Ag­[BF₄]. In these reactions, which afford [Mn­{κ²<i>Ge,N</i>-GeMe­(^<i>i</i>Pr₂bzam)^<i>t</i>Bu}­(CO)₄] (<b>2</b>) and [Mn­{κ²<i>Ge,N</i>-GeF­(^<i>i</i>Pr₂bzam)^<i>t</i>Bu}­(CO)₄] (<b>3</b>), respectively, the anionic nucleophile, Me^– or F^–, ends on the Ge atom while an arm of the amidinate fragment migrates from the Ge atom to the Mn atom. In contrast, the reaction of <b>1</b> with AgOTf (OTf = triflate) leads to [Mn­(OTf)­{Ge­(^<i>i</i>Pr₂bzam)^<i>t</i>Bu}­(CO)₄] (<b>4</b>), which maintains intact the amidinate–germylene ligand. Complex <b>4</b> is very moisture-sensitive, leading to [Mn₂{μ–κ⁴<i>Ge</i>₂<i>,O</i>₂-Ge₂^<i>t</i>Bu₂(OH)₂O}­(CO)₈] (<b>5</b>) and [^<i>i</i>Pr₂bzamH₂]­OTf (<b>6</b>) in wet solvents. In <b>5</b>, a novel digermanate­(II) ligand, [^<i>t</i>Bu­(OH)­GeOGe­(OH)^<i>t</i>Bu]^2–, doubly bridges two Mn­(CO)₄ units. The structures of <b>1</b>–<b>6</b> have been characterized by spectroscopic (IR, NMR) and single-crystal X-ray diffraction methods