Figure 2: Molecular structure of [Ga(bipy)3]2+• (32+).
Selected bond lengths are given in pm: Ga−N1=202.6(4), Ga−N2=202.6(4), Ga−N3=205.8(4), Ga−N4=208.2(4), Ga−N5=208.2(4), Ga−N6=205.8(4), C1−C2=149.2(12) and C3−C4=148.6(7), C5−C6=148.6(7). The earlier reported [Ga(bipy)3]3+ complex features a slightly longer average Ga−N bond length of 206.4 pm (cf. 205.5(4) pm for 32+) and a slightly shorter average C1,3,5−C2,4,6 bond length of 147.9 pm (cf. 148.8(9) pm for 32+)40. The [Al(ORF)4]– anions and all of the hydrogen atoms were omitted for clarity. The thermal ellipsoids are set at 50% probability. An alternative presentation, featuring ellipsoids for all atoms, is included in Supplementary Fig. 6. As an inset, the figure also includes the B3LYP/SV(P) level frontier and singly occupied Kohn-Sham orbital (SOMO) of 32+, electron density cutoff at 0.04 a.u. The calculated distances of the latter are in good agreement with the experimental results (bond lengths in pm, similar label scheme): Ga−N1=206.4, Ga−N2=206.8, Ga−N3=211.6, Ga−N4=213.2, Ga−N5=211.1, Ga−N6=209.1, C1−C2=145.7, C3−C4=147.7 and C5−C6=146.9. Yet, and more importantly, the SOMO is primarily located on the bipy ligands, thus speaking for a [GaIII{(bipy)3}•]2+ rather than a [(GaII)•(bipy)3]2+ complex. Applying the BHLYP/SV(P) level of theory, the SOMO is solely located on one bipy ligand, corresponding to a [Ga3+(bipy)2(bipy)•−]2+ complex (Supplementary Fig. 7). The calculated distances of the latter are in inferior agreement with the experimental results and therefore 32+ more likely corresponds to the [GaIII{(bipy)3}•]2+ formulation.
