Synthesis and characterization of a Bi10O8(OAr)16 oxo-cluster supported by p-tert-butylcalix[5]arene ligands.

Reaction of a non-dried monobenzylated [(t)BuC5(OBn)(OH)4] ligand with excess of Bi[N(SiMe3)2]3 yields a mixture of the dimeric complex 1 [Bi{(t)BuC5(OBn)(OH)}]2 in 12% yield and complex 2 [Bi10O8{(t)BuC5(OBn)(OH)}4] in 48% yield. The highly symmetric complex 2 features a Bi10O8(OAr)16 central core with tetra-, hexa- and heptacoordinated bismuth(iii) centers, and (μ2)-(μ4) bridging oxygen atoms all arranged in a I4 symmetrical pattern. Cluster 2 represents the largest bismuth oxo-cluster supported by calix[n]arene ligands reported to date.