Key points are not available for this paper at this time.
A paramagnetic Ni-containing molecular square has been synthesized in high yield from divergent precursors. An X-ray structure (shown in the picture) reveals the presence of an encapsulated tetrafluoroborate anion, which appears to be a requisite condition for the formation of the cyclic oligomer.
Campos-Fernandez et al. (Tue,) studied this question.