Two new coordination polymers containing the triangular [Mn3O(O2CR)6]0/+ units

The preparation and crystal structures of two linear chain compounds of oxo-centered triangular Mn clusters are reported. {[Mn4O(O2CMe)(8)(py)] center dot 2MeCN}(infinity) (1 center dot 2MeCN)infinity was formed when a concentrated solution of [Mn3O(O2CMe)(6)(py)(3)] center dot py in MeCN was left undisturbed at room temperature for several weeks. The repeating unit of the chain polymer (1 center dot 2MeCN)(infinity) consists of an oxo-centered trinuclear [Mn3O](6+) unit linked to a Mn-II center through mu-and mu(3)-O2CMe ligands. {[Mn3O(O2CPh)(7)(4,4 '-bpy)] center dot 3H(2)O}(infinity) (2 center dot 3H(2)O)(infinity) was prepared by reductive aggregation of (NBu4MnO4)-Mn-n in MeOH/benzoic acid in the presence of 4,4 '-bipyridine. The structure consists of chains of [Mn3O(O2CPh)(7)(4,4'-bpy)] units. The one-dimensional chains are linked into 2D networks by pi-stacking interactions between benzoate phenyl rings. Variable-temperature, solid-state dc magnetic susceptibility studies revealed the existence of anti-ferromagnetic exchange interactions within (1 center dot 2MeCN)(infinity). Complex (2 center dot 3H(2)O)(infinity), exhibits two different exchange couplings within its repeating unit and negligible intercluster interactions. The intracluster interactions stabilize an S = 2 ground state, but due to the topology of the cluster, two different parameter sets successfully reproduced the experimental data, i. e. J = 2.8 cm (1), J' = -22.5 cm (1) (A) and J = -22.2 cm (1), J' = 2.6 cm (1) (B). (C) 2008 Elsevier B. V. All rights reserved.