Collect. Czech. Chem. Commun. 2005, 70, 1861-1872

The Synthesis of 10-Halo-Substituted Derivatives of nido-7,8,9-PC2B8H11 and [nido-7,8,9-PC2B8H10]- and New Linear Correlations Between NMR Parameters

Josef Holub, Mario Bakardjiev and Bohumil Štíbr*

Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic, 250 68 Řež, Czech Republic


Halogenation of the eleven-vertex phosphadicarbaborane nido-7,8,9-PC2B8H10 (1) with CCl4, Br2 or I2 in the presence of anhydrous AlCl3 (solvents CCl4, CS2, and benzene, respectively) generated a series of 10-X-nido-7,8,9-PC2B8H10 (10-X-1) compounds (X = Cl, Br, and I) in yields 55, 65, and 63%, respectively. Anionic compounds [10-X-nido-7,8,9-PC2B8H10]- (10-X-2) (X = Cl, Br, I) were obtained by treatment of the corresponding neutral compounds with "proton sponge" (PS = 1,8-bis(dimethylamino)naphthalene). All compounds were characterized by multinuclear (11B, 1H, and 31P) NMR spectroscopy and [11B-11B]-COSY and 1H-{11B(selective)} NMR measurements that led to complete assignments of all 11B and 1H resonances to individual cluster positions. Interesting halo-substitution NMR effects are also discussed in terms of new linear correlations. All the changes in NMR chemical shifts (∆) induced at the various skeletal sites by halogeno substituents on specific sites can be related to an arbitrary reference skeleton and are, within experimental errors, linearly proportional to those induced at the substituted site (∆α) of the reference skeleton.

Keywords: Boron; Carboranes; Borane clusters; Heterodicarbaboranes; Phosphacarboranes; Phosphadicarbaboranes; NMR spectroscopy; Halogenations.

References: 18 live references.