Synthesis and Structures of Lead(II) Complexes with Substituted Derivatives of the Closo -Decaborate Anion with a Pendant N 3 Group.

In this work, we studied lead(II) and cobalt(II) complexation of derivatives [2-B 10 H 9 O(CH 2 ) 2 O(CH 2 ) 2 N 3 ] 2- and [2-B 10 H 9 O(CH 2 ) 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 [PbL 2 {An}] and binuclear [Pb 2 L 4 (NO 3 ) 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 [B 10 H 9 O(CH 2 ) 2 O(CH 2 ) 2 N 3 ] and the binuclear lead(II) complex [Pb 2 (phen) 4 (NO 3 ) 2 [B 10 H 9 O(CH 2 ) 5 )N 3 ] were determined by single-crystal X-ray diffraction. In complex [Pb 2 (phen) 4 (NO 3 ) 2 [B 10 H 9 O(CH 2 ) 5 )N 3 ], the boron cluster is coordinated by the metal atom only via the 3c2e MHB bonds. In complex [Pb(phen) 2 [B 10 H 9 O(CH 2 ) 2 O(CH 2 ) 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 CH 3 CN/water mixture, the binuclear lead(II) complex [(Pb(bipy)NO 3 )(Pb(bipy) 2 NO 3 )(B 10 H 9 O(CH 2 ) 2 O(CH 2 ) 2 N 3 )]·CH 3 CN·H 2 O 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 (Ph 4 P) 2 [B 10 H 9 O(CH 2 ) 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.