Treatment of metal (II) halides (metal= Cu, Ni, Co, Fe, Mn, Cr) with the potassium salts of carbohydrazides L1–L6 afforded Cu (L1) 2 (75%), Cu (L2) 2 (51%), Cu (L3) 2 (23%), Co (L1) 2 (57%), Cr (L1) 2 (62%), Ni (L1) 2 (76%), Ni (L2) 2 (62%), Ni (L3) 2 (62%), Ni (L4) 2 (13%), Ni (L5) 2 (11%), Ni (L6) 2 (29%),[Fe (L1) 2] 2 (28%), and [Mn (L1) 2] 2 (12%) as crystalline solids, where L1= Me2NNC (tBu) O−, L2= Me2NNC (iPr) O−, L3= Me2NNC (Me) O−, L4=( ...