Selective Arylation Reactions of Bismuth−Transition Metal Salicylate Complexes

Heterometallic bismuth−niobium or −tantalum salicylate complexes react with sodium tetraphenylborate to produce complexes in which one or more aryl groups have been transferred from boron to bismuth with the concomitant displacement of a η2-salicylato ligand. When the previously reported Bi2Ta2(sal)4(Hsal)4(OEt)4 (1) and BiTa4(μ-O)4(sal)4(Hsal)3(OiPr)4 (2) are treated with an alcoholic solution of NaBPh4, the compounds [PhBi(Hsal)Ta(sal)2(OEt)2·EtOH]2 (3) and PhBiTa4(μ-O)4(Hsal)2(sal)4(OEt)4·CH2Cl2 (4) are produced (sal = O2CC6H4-2-O2−, Hsal = O2CC6H4-2-OH−). The core geometries of the heterometallic complexes are retained. However, if preparations of compound 1 are treated with NaBPh4 without prior isolation of 1, [Ph2BiNb(sal)2(OMe)2]∞ (5) is produced instead. This compound was characterized both as a solvent-free crystalline form and as one containing a lattice diethyl ether. The compound exhibits a polymeric chain structure that can be viewed as alternating [Ph2Bi]+ and [Nb(sal)2(OMe)2]− units connected via bridging carboxylate groups. The arylation of the bismuth(III) center proceeds smoothly under mild conditions at room temperature, affording a new means for the mild functionalization of bismuth−transition metal heterometallic complexes.