Direct and facile synthesis of carbon substituted alkylhydroxy derivatives of cobalt bis(1,2-dicarbollide), versatile building blocks for synthetic purposes

Reactions of lithiated cobalt bis(1,2-dicarbollide)(1(-)) anion (1(-)) in presence of paraformaldehyde, ethylene oxide or trimethylene oxide led to the substitution of 1(-) at the C-atoms resulting in the high yield formation of monosubstituted alkylhydroxy derivatives [(1-HO(CH2)(n)-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co(III)](-) (n = 1-3) isolated as caesium salts (Cs2, Cs3, Cs4) along with disubstituted products of general formulation [(HO(CH2)(n)-1,2-C2B9H10)(2)-3,3'-Co(III)](-) (n = 1 3) (Cs5, Cs6 and Cs7). Disubstituted compounds are in fact a mixture of diastereoisomers denoted as 1,1'-anti(rac-), 1,2'-syn- and in case of Cs6 and Cs7 also 1,2-vicinal-isomer, from which only the anti-isomer could be isolated in pure form in case of shorter chain compounds Cs5 and Cs6. All these alkylhydroxy derivatives can serve as versatile precursors for the generation of a variety of functional molecules. Thus, reaction of Me(3)NH4 with NaH and one equivalent of POCl3 provided after hydrolysis the phosphorylated [(1-(HO)(2)P(O)-OC3H6-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co(III)](-) derivative, isolated in the form of trimethylammonium salt, Me(3)NH8 as the main product whereas reaction with half of the equivalent produces a high yield of phosphoric acid diester (Me3NH)(2)9 comprising in its structure two cages connected via propyl spacers to the central part. The calcium salt Ca(10)(2) of bridged ion [mu-(HOP(O)(OC3H6)(2))-(1,2-C2B9H10)(2)-3,3'-Co(III)](-) resulted from reaction of Me(3)NH7 with NaH and one equivalent of POCl3 followed by hydrolysis and addition of CaCl2. All new compounds were characterized by multinuclear NMR spectroscopy and mass spectrometry and the structure of Me3NH3 and that of the respective salts of the pure anti-stereoisomer of dialkylhydroxy derivatives Cs5 and Me3NH6 were established by X-ray crystallography.