Synthesis and crystal structure of high and low spin diruthenium complexes with diphenylformamidine and diphenyltriazene ligands

Abstract

The synthesis and structural characterization of the complex Ru 2(CN)(μ-DPhF) 4 ( 1) (DPhF= N, N ′-diphenylformamidinate) is reported. The reactivity of the axial position of Ru 2Cl(μ-O 2CMe)(μ-DPhF) 3 is studied and the crystal structures of Ru 2(N 3)(μ-O 2CMe)(μ-DPhF) 3 ( 2) and Ru 2(NCS)(μ-O 2CMe)(μ-DPhF) 3 ( 3) are described. The isolation of Ru 2Cl(μ-N 3Ph 2) 4 ( 4) and Ru 2Cl 2(μ-N 3Ph 2) 4 ( 5), and the crystal structure determination of complex 4, which constitutes the first example of a chlorotriazenido derivative, are also reported. Each complex forms discrete dinuclear molecules in the solid state, having (each diruthenium unit) one free axial position. The shortest Ru–Ru distance [2.286(2) Å] is observed in the cyano derivative ( 1) and the longest [2.4747(11) Å] is found in the triazenido complex ( 4). The azido ( 2) and isothiocyanato ( 3) derivatives show similar Ru–Ru distances of 2.3182(11) and 2.3159(4) Å, respectively. Complexes 2 and 4 display magnetic moments at room temperature corresponding to three unpaired electrons in agreement with the σ 2 π 4 δ 2( π ∗ δ ∗) 3 ground-state configuration, whereas compounds 1 and 3 are low spin complexes with only one unpaired electron. Only very few examples of low spin diruthenium(II,III) species have been previously characterized. The diruthenium(III) compound 5 is diamagnetic.