Increasing Solubility and Stability of Linear Tricobalt(II) Chains with depa (Diethyldipyridylamide) Ligands

A new and more basic ligand has been used to make two new tricobalt extended metal atom chains (EMACs),
namely, Co3(depa)4Cl2, 3, and Co3(depa)4(CN)2, 4. The depa ligand is di(4-ethyl-2-pyridyl)amide, a useful modification
of the well-known di(2-pyridyl)amide, dpa, ligand. The new compounds have been thoroughly characterized, and
informative comparisons are made of 3 with Co3(dpa)4Cl2, 1, and 4 with Co3(dpa)4(CN)2, 2, which were described
several years ago. Introduction of the eight ethyl groups into the trimetal compounds improves solubility, makes
oxidations easier, and allows for a more complete examination of the magnetic susceptibility as a function of
temperature for 3 than was possible for 1. The data clearly indicate that the upper state for 3 has S = 3/2 and
suggest that this is the case for 1 as well.