Pentamine mixtures

To a solution of tetraethylene pentamine pentahydrochloride (tetren.5HCl, Aldrich) (1.12 g, 3.0 mmol) dissolved in 20 mL of water is added 600 mg of NaOH (15 mmol, 5 equiv) followed by nickel(II) perchlorate (755 mg, 2.06 mmol) dissolved in 10 mL of water. The mixture is stirred for 20 min. Then silver perchlorate (3.12 g, 15 mmol, 5 equiv) is added in order to eliminate the chloride ions. The solution is left stirring for 1 h in the dark, then the solution is hltered through a glass frit to separate silver chloride. Then 20 mL of acetonitrile is added to the deep blue filtrate. A solution of potassium hexacyanochro-mate(III) (0.110 g, 0.33 mmol) in a minimum of water is added drop by drop, and the solution is left standing for a few days. The red-purple octahedral crystals that form are collected, washed with water, and air-dried (0.540 mg, 63% yield). 

Some pentaamine hgands are shown in (17), (19), and (207-215). Commercially available technical tetraethylene-pentamine is a mixture of linear tetren (207) and branched chain trenen (208), so five-coordinate [Cu(trenen)] + and octahedral [CoCl(tetren)] + can be obtained in reasonable yields from the same polyamine mixture.Alternatively, these ligands can be synthesized in situ from Co complexes of tren (191) ortrien (178), and coordinated amino-acetaldehyde. ... 

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