I tried the published method but failed. [Ref-Hexaaquacopper(II) dichloride bis(hexamethylenetetramine) tetrahydrate-Acta Cryst. (2008). E64, m1024]. Instead of getting a solution (described in the reference) I get yellowish ppt upon addition of aq. CuCl2 in HMTA solution (1:1 W: EtOH). End product remains unchanged after prolonged hydrothermal treatment. I will run EDX to find out nature of the ppt.
That's not a question of reduction to Cu(I). Because HMTA is a relatively strong base, you need a bit lower pH. Use dilute solutions.
Dear Cristian Ene and Leslaw Sieron, thank you so much for your very helpful answers. Now I have something more to share. I did EDX analysis of ppt (which was pastel greenish blue once dried) as well as of supernatant (post evaporative drying- yellowish white crystals). The results are:
1.The precipitate seems to be Tribasic copper Chloride (TBCC) i.e. Cu2 (OH)3Cl with Cu:O:Cl in 2:3:1 ratio(EDX data). CuCl2 is known to form TBCC by base hydrolysis at pH 4-7.
2. The dried supernatant carries C, N,O,Cl in approx. 12:6:1:1.5 ratio unlike the HMTA ratio of C and N of 6:4 or 3:2. (EDX does not give hydrogen). So the lost Cl of CuCl2 conversion to TBCC is part of supernatant of unknown composition.
In a new reaction I used 1:2.5 molar ratio (1mmol:2.5 mmol) of CuCl2.2H2O solution (doubly diluted) and HMTA solution (4 times diluted) and slowly added the HMTA solution in to the salt solution. But ppt formed once again which redissolve upon HCl addition and clear solution formed (0.6ml conc. HCl) . After heating at 100c the ppt formed again which redissolve with small addition (1.5ml) of HCl. expected pH (pH Strip only) was between 3-6. No further ppt formation is now seen. Let's see if the complex forms this time. Thank you both once again.
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