PROBING THE COORDINATION CHEMISTRY OF [ZR6BCL12](- A CLUSTER ESPECIALLY AMENABLE TO NMR-STUDY() )

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. B-11 NMR spectra for [(Zr6BCl12)Cl6-xLx](x-5) (L = CH3CN, CH3OH, and pyridine; x = 1-6 ) are reported. Exceedingly narrow B-11 lines are generally observed f or these clusters. Two-bond ((2)J(P-Zr-B) = 8.8 Hz) and three-bond cou pling constants ((3)J(P-O-Zr-B) = 1.9 HZ) are observed for the cluster complexes [(Zr6BCl12)(PR3)(6)](+) and [(Zr6BCl12)(OPR3)(x)L6-x](+) (L = CH3CN and PR3), respectively, in both B-11 and P-31 NMR spectra. Sp in-lattice relaxation times (T-1's) for B-11 were measured for several cluster complexes.. Homoleptic species; [(Zr-BCl12)L-6](+) (L = CH3CN , CH3OH, pyridine), exhibit very long times and that for [(Zr6BCl12)(N CCH3)(6)](+) is the longest ever measured (T-1 = 108 s) for the B-11 n ucleus. A thermodynamic analysis of spectra for the [(Zr6BCl12) (CH3OH )(6-x)(py)(x)](+) (x = 0-5) System reveals that [Zr6BCl12](+) binds py ridine more strongly than methanol by about 3 kJ/mol. Crystallographic structural analyses of [(Zr6BCl12)Cl(py)(5)]. 3CH(3)CN and [pyH]-{cis -[(Zr6BCl12)Cl-2(py)(4)]}. 3py are also reported. The following parame ters were determined for these two compounds: [(Zr6BCl12)Cl(py)(5)]. 3 CH(3)CN, orthorhombic, Pbcm, a 13.4268(1) Angstrom, b = 25.8258(1) Ang strom, c 14.5918(2) Angstrom, Z = 4; [pyH]{cis-[(Zr6BCl12)Cl-2(py)(4)] }. 3py, monoclinic, C2/c, a = 14.5999(3) Angstrom, b = 21.2298- (5) An gstrom, c 19.8292(5) Angstrom, beta = 101.892(1)degrees, Z = 4.