Synthesis and Structures of Lead(II) Complexes with Substituted Derivatives of the Closo-Decaborate Anion with a Pendant N₃ Group

In this work, we studied lead(II) and cobalt(II) complexation of derivatives [2-B10H9O(CH2)(2)O(CH2)(2)N-3](2-) and [2-B10H9O(CH2)(5)N-3](2-) of the closo-decaborate anion containing pendant azido groups in the presence of 1,10-phenanthroline and 2,2'-bipyridyl. Mononuclear [PbL2{An}] and binuclear [Pb2L4(NO3)(2){An}] lead complexes (where {An} is the N-3-substituted boron cluster) were isolated and studied by IR spectroscopy and elemental analysis. The mononuclear lead(II) complex [Pb(phen)(2)[B10H9O(CH2)(2)O(CH2)(2)N-3] and the binuclear lead(II) complex [Pb-2(phen)(4)(NO3)(2)[B10H9O(CH2)(5))N-3] were determined by single-crystal X-ray diffraction. In complex [Pb-2(phen)(4)(NO3)(2)[B10H9O(CH2)(5))N-3], the boron cluster is coordinated by the metal atom only via the 3c2e MHB bonds. In complex [Pb(phen)(2)[B10H9O(CH2)(2)O(CH2)(2)N-3], the coordination environment of the metal includes BH groups of the boron cluster and the oxygen atom of the exo-polyhedral substituent. When the reaction was performed in a CH3CN/water mixture, the binuclear lead(II) complex [(Pb(bipy)NO3)(Pb(bipy)(2)NO3)(B10H9O(CH2)(2)O(CH2)(2)N-3)]CH3CNH2O was isolated, where the boron cluster acts as a bridging ligand between lead atoms coordinated by the boron cage via the O atoms of the substituent and/or the BH groups. In the course of cobalt(II) complexation, the starting compound (Ph4P)(2)[B10H9O(CH2)(5)N-3] was isolated and its structure was also determined by X-ray diffraction. Although a number of lead(II) complexes with coordinated N-3 are known from the literature, no complexes with the boron cluster coordinated by the pendant N-3 group involved in the metal coordination have been isolated.