Coordination of 4,7-dihydro-5-methyl-7-oxo-[1,2,4]triazolo[1,5-a]-pyrimidine (Hmpto) to copper(II): Crystal structures of [Cu(en)2(mtpo)2] and [Cu(dach)2(OH2)2](mpto)2; en is 1,2-ethylenediamine and dach is cis-1,2-diaminocyclohexane