Second-sphere coordination of ‘star’-shaped hexakis(N-pyridin-4-one)benzene (HPOB) with hexakis(methanol)nickel(II) nitrate; unusual (NO3 −)(HPOB)(NO3 −) π-stacked ‘sandwiching’

It is shown by X-ray studies that the compound Ni(HPOB)(NO3)2(MeOH)9 [where HPOB=hexaxis(N-pyridin-4-one)benzene] contains [Ni(MeOH)6]2+ cations hydrogen-bonded to the oxygen atoms of the pyridone units in HPOB, with the resulting six-connectivity at both metal and HPOB producing a three-dimensional network array essentially topologically equivalent to the α-Po structure. The pyridone rings in the HPOB molecules are arranged orthogonally to the central C6 ring and the nitrate anions form an unusual (NO3 −)(HPOB)(NO3 −) ‘sandwich’ by a combination of π-stacking and CH⋯O hydrogen bonds.