Complexation and exopolyhedral substitution of the terminal hydrogen atoms in the decahydro-closo-decaborate anion in the presence of cobalt(II)

Reactions between the decahydro-closo-decaborate anion and nitrogen-containing organic ligands L (2,2'-bipyridine (Bipy), 2,2'-bipyridylamine (BPA), phenanthridine (5NPhen)) in the presence of the cobalt(II) ions have been found to give either the corresponding cobalt(II) complexes or the substituted derivatives of the boron cluster depending on the reaction conditions (temperature, solvent (CH3CN or DMF), air/inert atmosphere, and the reagent ratio). It was found that the mono-substituted derivative [2-B10H9OC(H)O](2-) with the corresponding residue of the DMF molecule as the substituent can be obtained in the presence of cobalt(II) by the reaction between CoCl2, [B10H10](2-), and DMF whereas cobalt(II) complexes with Bipy, BPA and 5NPhen have been prepared in the presence of the corresponding ligands. In addition, the whole DMF residue, the -OC(H)N(CH3)(2) function, can be introduced in the boron cluster by the acid-catalyzed nucleophilic substitution when [B10H11](-) was heated in DMF. Crystals of compounds [Co(Phen)(3)][2-B10H30C(H)O]center dot 3DMF (Phen is 1,10-phenanthroline additionally introduced into the reaction solution), (Et3NH)[2-B10H9-OC(H)N(CH3)(2)], [Co(BPA)(2)(DMF)(2)(B10H10]center dot C6H6, [Co(Bipy)(3)] [BioHlo], and [Co(SNPhen)(2)Cl-2] were characterized by single crystal X-ray diffraction. Both the substituted derivatives of the boron cluster synthesized here contain exopolyhedral B-O bonds. (C) 2019 Elsevier Ltd. All rights reserved.