Encouraging Chromium(III) Ions to Form Larger Clusters: Syntheses, Structures, Magnetic Properties and Theoretical Studies of Di- and Octametallic Cr Clusters

A simple methodology for constructing ferromagnetically coupled Cr(iii) compounds

A large family of chromium(iii) dimers has been synthesised and magneto-structurally characterised using a combination of carboxylate and diethanolamine type ligands. The compounds have the general formula [Cr2(R1-deaH)2(O2CR2)Cl2]Cl where R1 = Me and R2 = H (1), Me (2), CMe3 (3), Ph (4), 3,5-(Cl)2Ph (5), (Me)5Ph (6), R1 = Et and R2 = H (7), Ph (8). The compound [Cr2(Me-deaH)2Cl4] (9) was synthesised in order to study the effect of removing/adding the carboxylate bridge on the observed magnetic behaviour. Direct current (DC) magnetic susceptibility measurements showed ferromagnetic (FM) exchange interactions between the Cr(iii) centres in the carboxylate bridged family with coupling constants in the range +0.37 < J < +8.02 cm-1. Removal of the carboxylate to produce the dialkoxide-bridged compound 9 resulted in antiferromagnetic (AFM) exchange between the Cr(iii) ions. DFT calculations reveal the ferromagnetic exchange is the result of an orbital counter-complementarity effect occuring upon introduction of the bridging carboxylate.

Magneto-structural correlations in a family of di-alkoxo bridged chromium dimers

A series of di-alkoxo bridged Cr(iii) dimers have been synthesised using pyridine alcohol ligands.

Solvothermal synthesis of discrete cages and extended networks comprising {Cr(iii)3O(O2CR)3(oxime)3}2− (R = H, CH3, C(CH3)3, C14H9) building blocks

We present the solvothermal synthesis, structural and magnetic characterisation of a family of Cr(iii) cages and extended networks comprising {Cr(iii)₃O(O₂CR₁)₃(R₂-sao)}²⁻ (R₁ = H, CH₃, C(CH₃)₃, C₁₄H₉; R₂ = Me, Ph, ^tBu, C₁₀H₆) building blocks.

Bis(μ-2-hydroxymethyl-2-methylpropane-1,3-diolato)bis[dichloridotitanium(IV)] diethyl ether disolvate

The title complex, [Ti₂Cl₄{CH₃C(CH₂O)₂(CH₂OH)}₂], lies across a centre of symmetry with a diethyl ether solvent mol­ecule hydrogen bonded to the –CH₂OH groups on either side of it. The Ti^IV atom is coordinated in a distorted octa­hedral geometry by a tripodal ligand and two terminal chloride atoms. There are three coordination modes for the tripodal ligand distinguishable on the basis of their very different Ti—O bond lengths. For the terminal alkoxo ligand, the Ti—O distance is 1.760 (1) Å, the asymmetric bridge system has Ti—O bond lengths of 1.911 (1) and 2.048 (1) Å. The Ti—O bond length for the alcohol O atom is the longest at 2.148 (1) Å.