Facile synthesis of bismuth(III) and antimony(III) complexes supported by silylated calix[5]arenes.
A series of bismuth(III) and antimony(III) complexes supported by silicon-containing calix[5]arene ligands were synthesized and fully characterized by NMR, X-ray, IR, mp, UV/vis, and elemental analysis. Reaction of the para-tert-butylcalix[5]arene [(t)BuC5(H)(5)] disodium salt, Na(2) x (t)BuC5(H)(3), with 1 equiv of R(2)SiCl(2) (R = Me, (i)Pr, Ph, CH=CH(2)) or treatment of the (t)BuC5(H)(5) lower rim monobenzyl ether [(t)BuC5(Bn)(H)(4)] in a 1:1 ratio with Me(2)Si(NMe(2))(2) yields the (t)BuC5(SiRR')(H)(3) (1-5) and (t)BuC5(Bn)(SiMe(2))(H)(2) (6) ligands, respectively. The (1)H NMR spectra of the (t)BuC5(SiRR')(H)(3) (1-5) ligands show three pairs of doublets and three singlets for the (t)Bu peaks, consistent with a C(s) symmetry. In the case of the (t)BuC5(Bn)(SiMe(2))(H)(2) (6) ligand, the presence of the monobenzyl group changes the (1)H NMR patterns to indicate a C(1) symmetry. Treatment of (t)BuC5(SiRR')(H)(3) (1-5) or (t)BuC5(Bn)(SiMe(2))(H)(2) (6) with 1 equiv of M(O(t)Bu)(3) (M = Bi, Sb) or Sb(NMe(2))(2) readily yields metalated products of the type [M{(t)BuC5(SiRR')}] (7-16) and [MX{(t)BuC5(Bn)(SiMe(2))}] (X = O(t)Bu, (NMe(2))(2)) (17-19), respectively. All monometallic complexes [M{(t)BuC5(SiRR')}] (7-19) display excellent solubility in organic solvents including pentane and hexane. The (1)H NMR patterns for complexes 7-16 are consistent with a 1,2- or 1,3-alternate conformation while complexes [MX{(t)BuC5(Bn)(SiMe(2))}] (17-19) display patterns for a C(1) symmetry. All crystals show monomeric structures. Ligand (t)BuC5(SiPh(2))(H)(3) (3) displays a distorted cone conformation while the presence of the monobenzyl ether in (t)BuC5(Bn)(SiMe(2))(H)(2) (6) forces a partial cone conformation. Complexes 7-19 all display a distorted 1,2-alternate conformation with the metal centers displaying coordination numbers of three, four or five. No Si...M interactions were observed.
Department of Chemistry, Texas Christian University, Box 298860, Fort Worth, Texas 76129, USA.
Daniel
D
Mendoza-Espinosa
Tracy A
TA
Hanna