Probing the Coordination Chemistry of [Zr6BCl12]+: A Cluster Especially Amenable to NMR Study Academic Article uri icon

abstract

  • NMR spectroscopy is demonstrated to be a powerful analytical tool for the study of solvolysis and ligand-exchange chemistry of the [Zr6BCl12]+ cluster in acetonitrile, methanol, and pyridine. 11B NMR spectra for [(Zr6BCl12)Cl(6-x)L(x)](x-5) (L = CH3CN, CH3OH, and pyridine; x = 1-6) are reported. Exceedingly narrow 11B lines are generally observed for these clusters. Two-bond (2J(P-Zr-B) = 8.8 Hz) and three-bond coupling constants (3J(P-O-Zr-B) = 1.9 Hz) are observed for the cluster complexes [(Zr6BCl12)(PR3)6]+ and [(Zr6BCl12)(OPR3)(x)L(6-x]+ (L = CH3CN and PR3), respectively, in both 11B and 31P NMR spectra. Spin-lattice relaxation times (T1's) for 11B were measured for several cluster complexes Homoleptic species, [(Zr6BCl12)L6]+ (L = CH3CN, CH3OH, pyridine), exhibit very long times and that for [(Zr6BCl12)(NCCH3)6]+ is the longest ever measured (T1 = 108 s) for the 11B nucleus. A thermodynamic analysis of spectra for the [(Zr6BCl12)(CH3OH)(6- x)(py)(x)]+ (x = 0-5) systems reveals that [Zr6BCl12]+ binds pyridine more strongly than methanol by about 3 kJ/mol. Crystallographic structural analyses of [(Zr6BCl12)Cl(py)5]3CH3CN and [pyH]-{cis- [(Zr6BCl12)Cl2(py)4]}3py are also reported. The following parameters were determined for these two compounds: [(Zr6BCl12)Cl(py)5]CH3CH, orthorhombic, Pbcm, a = 13.4268(1) , b = 25.8258(1) , c = 14.5918(2) , Z = 4, [pyH]{cis-[(Zr6Bl12)Cl2(py)4]}py, monoclinic, C2/c, a = 14.5999(3) , b = 21.2298(5) , c = 19.8292(5) , = 101.892(1), Z = 4.

published proceedings

  • Journal of the American Chemical Society

author list (cited authors)

  • Xie, .., Reibenspies, J. H., & Hughbanks, T.

publication date

  • January 1, 1998 11:11 AM