Carbamide-containing complexes of lanthanides: competition of hydrogen bonding and polyiodide ion formation

The carbamide complexes of lanthanide polyiodoiodates [Tm(ur)₇][I₃]₃·2I₂, [Yb(ur)₆][I₃]₃ and [Lu(ur)₆][I₃]₃ [ur is O=C(NH₂)₂] have been synthesized and structurally characterized. The structure-forming role of the pentaiodide ions taking part in the formation of extended channels 10–12 Å in diameter with incorporated hepta(carbamide)thulium cations combined to one another into infinite columns due to H-bonding, or the triiodide ions forming lace-like net with isolated hexa(carbamide)ytterbium(III) or hexa(carbamide) lutetium(III) cations located in the net holes has been revealed.