MULTINUCLEAR MAGNETIC-RESONANCE SPECTROSCOPY OF CENTERED ZIRCONIUM HALIDE CLUSTERS

Nuclear magnetic resonance spectra for each of the interstitials withi n centered [(Zr(6)Z)(Cl12Cl6-nLn)-Cl-i-L-a](m-) clusters (Z = Be, B, C , N, Mn, and Co; L = Cl-, AlCl4-, CH3CN, and/or PPh3; n = 0-6) are rep orted. For C-and Mn-centered clusters, chemical shifts for both solids and solutions have been measured. Chemical shifts for B-centered clus ters were measured in solution. Chemical shifts for Be-, N-, and Co-ce ntered clusters were measured in the solid state. Interstitial carbide resonances for all 10 axially substituted species ({[(Zr6C)Cl-12](CH3 CN)(n)Cl6-n}(n-4), n = 0-6) have been located; their chemical shifts r ange from 457.7 ppm for {[(Zr6C)Cl-12]Cl-6}(4-) to 480.1 ppm for {[(Zr 6C)Cl-12](CH3CN)(6)}(2+). B-11 chemical shifts for boride-centered clu sters ({[(Zr6B)Cl-12](CH3CN)(n)Cl6-n}(n-5), n = 0-5) range from 185 to 193.8 ppm. B-11 and C-13 data reveal the axially bound chlorides to b e substitutionally inert. Chemical shifts for Mn-55-centered clusters range from 5359 ppm (isotropic) for solid RbZr6Cl14Mn to 5618 ppm for [(Zr6Mn)Cl12Cl6](5-) in a Cl- -rich molten salt. These are the most de shielded manganese compounds presently known. Solid-state Be-9 for K3Z r6Cl15Be, N-15 for Zr6Cl15N, and Co-59 for Zr6Cl15Co reveal chemical s hifts of 77.1, 271, and 4082 ppm, respectively (the Be-9 data is not c orrected for the second-order quadrupolar contribution). A discussion of the origin of large paramagnetic shielding contributions to the che mical shifts of the interstitial atoms is given.