Alkylated Poly amine Complexes of Palladium II

Submitted by F. S. WALKER S. N. BH ATTACH ARY A,t and C. V. SENOFF Checked by KENT BAREFIELD and GARY M. FREEMAN  

Y-BIS[2-(DIMETHYLAMINO)ETHYL]W Y-DIMETHYL-1,2-ETHANEDIAMINE ] CHLOROPALLADIUM(II) CHLORIDE, [PdCl(trenMe6)]Cl 

Palladium(II) chloride (1.0 g, 5.6 mmole) is added to a solution of 30 mL water and 1.0 mL concentrated HC1 contained in a 100-mL, round-bottomed flask. The resulting mixture is heated under reflux until all the palladium(II) chloride dissolves. The dark reddish-brown solution is then allowed to cool to room temperature, and trenMe63 (1.65 g, 7.1 mmole) is slowly added. The resulting yellow solution is then heated at reflux for 30 minutes and allowed to cool again to room temperature. Small portions of Na2C03 are carefully added to the solution until the pH is adjusted to approximately 11.0 as measured by using a colorpHast indicator stick [the checkers report that careful addition of 25% NaOH solution works equally well.]. The solvent is removed by means of a rotoevaporator and the yellow residue is dried in vacuo at room temperature. The palladium complex is extracted from the residue by the successive use of four 25-mL portions of hot chloroform. The combined chloroform extracts are filtered to remove insoluble materials and are evaporated to near dryness on the rotoevaporator. Acetone (30 mL) is added to precipitate the product, which is collected by filtration and dried in vacuo at room temperature. The yield is 1.2 g (52%) [the checkers report a yield of 2.15 g (93%) when ether is used to precipitate the product which is somewhat soluble in acetone.]. 

Nj -bis [2-(dimethylamino)ethyl] -TV V -dimethyl-l, 2-ethane diamine] chloropall-adium(Il) chloride is a yellow, diamagnetic solid that melts with decomposition at 210°. It is somewhat hygroscopic and is best stored in a moisture-free atmosphere. It is very soluble in water, chloroform, and dichloromethane but insoluble in most other common laboratory solvents. 

The H nmr spectrum in D20 exhibits a single resonance at 2.52 ppm for the methyl protons with DSS, the sodium salt of 2,2-dimethyl-2-silapentane-5-sulfonic acid as reference. The electronic spectrum for an aqueous solution is characterized by an absorption maximum at 358 nm (e = 7.4 Lrnole 1 cm 1) in H20. Other physical properties are described in the literature [the checkers report 5(CH3) = 2.6 ppm with Xmax = 336 nm, e = 650 Lmol 1 cm 1 ]. 

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