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

Halogenation of the eleven-vertex phosphadicarbaborane nido-7,8,9-PC 2 B 8 H 1 0 (1) with CCl 4 , Br 2 or I 2 in the presence of anhydrous AlCl 3 (solvents CCl 4 , CS 2 , and benzene, respectively) generated a series of 10-X-nido-7,8,9-PC 2 B 8 H 1 0 (10-X-1) compounds (X = Cl, Br, and I) in yields 55, 65, and 63%, respectively. Anionic compounds [10-X-nido-7,8,9-PC 2 B 8 H 1 0 ] - (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 ( 1 1 B, 1 H, and 3 1 P) NMR spectroscopy and [ 1 1 B- 1 1 B]-COSY and 1 H-{ 1 1 B(selective)} NMR measurements that led to complete assignments of all 1 1 B and 1 H 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 (A) 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 (Δα) of the reference skeleton.