Isolation of a water-stable B-centered hexazirconium bromide cluster, trans-[(Zr6BBr12)Br4(H2O)3]3
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(K 4 Br) 2 (Zr 6 Br 18 B), a B-centered hexazirconium cluster compound, is readily dissolved into aqueous media to form red solutions. 11 B NMR spectra of the cluster in aqueous LiBr solutions indicate that diamagnetic [Zr 6 BBr 12 ] + species are present as the result of one-electron oxidation of [Zr 6 BBr 12 ] 0 present in the precursor. Electrochemical measurements of the cluster in 6 M HBr solution shows that the diamagnetic [Zr 6 BBr 12 ] + cluster is too weakly reducing to reduce protons. (H 3 O) 3 {trans-[(Zr 6 BBr 12 )Br 4 (H 2 O) 2 ]}13H 2 O (1) was isolated when an aqueous HBr solution of the cluster was cooled to -20C. Crystallographic structural analysis of 1 (monoclinic, C2/c, a = 24.3557(7) , b = 10.0135(1) , c = 18.6388(6) , = 92.370(2), Z = 4.) is reported. Both 11 B NMR spectroscopy and crystallography show that bromide coordinates the cluster much more weakly than chloride. 1999 ditions Scientifiques et Mdicales Elsevier SAS. All rights reserved.