“…native approach is based on a series of reports which show that singly-bridged bipolar structures must be considered as significant in non-aqueous solution. For aluminium, NMR studies 5 on this point are supported by Raman spectroscopy of Al 2 Br 6 in aromatic solvents, 16 while for Ga 2 X 6 , NMR spectra, 4 vapour pressure measurements, 17 and electron spin resonance spectroscopy 18 all support the structure shown as Fig. 1B.…”