Coordination driven self-assembly of [2 + 2 + 2] molecular squares: synthesis, crystal structures, catalytic and luminescence properties

Ten molecular squares were prepared through coordination-driven self-assembly and their catalytic activity and luminescence properties are reported.

Unusual oxidation state distributions observed for two mixed-valence heptanuclear manganese disc-like clusters

The synthesis, structures and magnetic properties of two new mixed-valence heptanuclear manganese clusters are described. Both complexes utilize triethanolamine (teaH(3)) as a bridging ligand, displaying near planar, disc-like metal topologies and are of formulae [Mn(II)(4)Mn(IV)(3)(tea)(teaH(2))(3)(peolH)(4)](BF(4))(2)·solv (1) and [Mn(II)(4)Mn(III)(3)F(3)(tea)(teaH)(teaH(2))(2)(piv)(4)(Hpiv)(chp)(3)]·0.5MeCN (2). Compound 1 is a rare mixed-valence compound containing Mn(II) and Mn(IV) ions only and is the first example of a heptanuclear disc with a {Mn(II)(4)Mn(IV)(3)} oxidation state distribution. Compound 2 is a {Mn(II)(4)Mn(III)(3)} complex and displays a unique arrangement of oxidation states within the disc, when compared to other known {Mn(II)(4)Mn(III)(3)} examples. Variable temperature DC and AC magnetic susceptibility studies were carried out for 1 and 2 in the 2-300 K temperature range. Compound 1 displayed an increase in the χ(M)T susceptibility values as the temperature is decreased indicating dominant ferromagnetic interactions are present within the cluster. Fits of the χ(M)T vs. T data reveals an S = 23/2 ground state, with several close lying excited states within 1 cm(-1). Compound 2 displays an overall decrease in the χ(M)T value as the temperature is decreased down to 2 K indicating dominant antiferromagnetic interactions present with a probable S = 4 ground state as determined from the DC and AC susceptibility data.

Supertetrahedral icosanuclear and ring-like decanuclear mixed valent manganese(II/III) triethanolamine clusters

The synthesis and characterisation of three new mixed-valent manganese clusters [Mn(II)₄Mn(III)₁₆O₁₂(OH)₄(tea)₈(chp)₄]·6MeOH·4H₂O (1), [Mn(II)₆Mn(III)₄(teaH)₄(teaH₂)₂(tpaa)₆(F)₈]·2Et₂O·4MeCN (2) and [Mn(II)₆Mn(III)₄(teaH)₄(teaH₂)₂(2-bpca)₆(F)₈]·4MeCN (3) are reported. They were obtained by the reaction of simple manganese salts with triethanolamine (teaH₃), triethylamine (NEt₃) and the appropriate co-ligand. In the case of 1, 6-chloro-2-hydroxypyridine (Hchp) was used, for 2, triphenylacetic acid (tpaa) and 3, 2-biphenylcarboxylic acid (2-bpca). The core of 1 is a Mn₂₀ supertetrahedron, while the cores of 2 and 3 are identical and have distorted ring-like topologies. Variable-temperature, solid-state DC and AC magnetic studies were performed on 1-3 in the 2-300 K (DC) and 2-18 K (AC) ranges. Cluster 1 has a S = 9 ground state with excited S states, larger in value than 9, close in energy. No SMM features were apparent in 1. In contrast, clusters 2 and 3, with S = 12 or 13 ground states, and with excited S levels of lower value than 12 lying close in energy, do show SMM features, albeit below 2 K in their AC out-of-phase, frequency dependent data.