A streamlined synthesis of extended thiophloroglucinol ligands and their trinuclear NiII3 complexes.

A protocol for the synthesis of trinucleating C3-symmetric ligands based on a central meta-phenylene bridging 1,3,5-trimercaptobenzene (thiophloroglucinol) backbone has been established. The key compound turned out to be the trialdehyde obtained from the triple nucleophilic attack of dimethyldithiocarbamate at 1,3,5-tribromo-2,4,6-triformylbenzene. Reacting this trialdehyde with six equivalents of a primary amine results in the simultaneous dithiocarbamate cleavage and Schiff-base formation providing the extended thiophloroglucinol ligands H3bertdien, H6bert(Me), H6bert(t-Bu2), and H6habbi. Reaction with Ni(II) leads to the formation of the trinuclear Ni(II)3 complexes [(bertdien)Ni(II)3](X)3 (X = BPh4(-), BF4(-)), [(bert(Me))Ni(II)3], [(bert(t-Bu2))Ni(II)3], and [(habbi)Ni(II)3], which are characterized spectroscopically, electrochemically, and crystallographically.

Bioinspired enhancement of superexchange: from 1,3,5-trihydroxybenzene-bridged to 1,3,5-trimercaptobenzene-bridged trinuclear copper(II) complexes.

An unprecedented trinucleating ligand with a central 1,3,5-trimercaptobenzene unit and its trinuclear Cu(II)(3) complex are presented. The high covalency of the difficult-to-realize Cu(II)-SR bond provides an order of magnitude increase in the superexchange interaction in comparison to its oxygen analogue.

A Mn(III) triplesalen-based 1D pearl necklace: exchange interactions and zero-field splittings in a C3-symmetric Mn(III)6 complex.

The reaction of the tert-butyl-substituted triplesalen ligand H(6)talen(t-Bu(2)) with 2.8 equivalents of Mn(OAc)(2) x 4 H(2)O in MeOH in the presence of NaBPh(4) results in the formation of the one-dimensional (1D) coordination polymer {[{(talen(t-Bu(2)))Mn(3)(MeOH)}(2)(mu(2)-OAc)(3)](mu(2)-OAc)}(n)(BPh(4))(2n) ({[Mn(III)(6)](OAc)}(n)(BPh(4))(2n)) which has been characterized by FTIR, elemental analysis, ESI-MS, single-crystal X-ray diffraction and magnetic measurements. The triplesalen ligand (talen(t-Bu(2)))(6-) provides three salen-like coordination compartments bridged in a meta-phenylene arrangement by a phloroglucinol backbone resulting in the trinuclear Mn(III) base unit {(talen(t-Bu(2)))Mn(3)}(3+). Two of these base units are bridged by three inner acetate ligands giving rise to the hexanuclear complex [{(talen(t-Bu(2)))Mn(3)(MeOH)}(2)(mu(2)-OAc)(3)](3+) ([Mn(III)(6)](3+)). These complexes are bridged by a single external acetate to form a 1D chain as pearls in a pearl necklace. Variable temperature-variable field and mu(eff)vs. T magnetic data have been analyzed in detail by full-matrix diagonalization of the appropriate spin-Hamiltonian consisting of isotropic exchange, zero-field splitting, and Zeeman interaction taking into account the relative orientation of the D-tensors. Satisfactory reproduction of the experimental data have been obtained for parameters sets J(1) = -(0.60 +/- 0.15) cm(-1), J(2) = -(1.05 +/- 0.15) cm(-1), and D(Mn) = -(3.0 +/- 0.7) cm(-1) with J(1) describing the exchange through the phloroglucinol backbone and J(2) describing the exchange through the inner acetates. The non-necessity to incorporate the bridging outer acetates correlates with the longer Mn-O bonds. The experimental data can neither be analyzed without incorporating zero-field splitting nor by the application of a single effective spin ground state.

Ferromagnetic coupling by orthogonal magnetic orbitals in a heterodinuclear CuIIVIV=O complex and in a homodinuclear CuIICuII complex.

The heterodinuclear complex [LCuIIVIVO] 1 was synthesized by using a new unsymmetric dinucleating ligand based on 1,8-naphthalenediol, whereas the homodinuclear CuIICuII complex 2 has a bridging beta-diketimineamid unit. Here we report on the synthesis, molecular structures, and magnetic properties of 1 and 2. In the solid state, both complexes dimerize to tetranuclear entities 1(2) and 2(2). The intradimer interaction in both complexes is ferromagnetic because of the orthogonality of the magnetic orbitals (J12 = +45.6 cm(-1) in 1 and +4.8 cm(-1) in 2). The interdimer interaction in 1 is also ferromagnetic, giving a St = 2 ground state.