Investigation of Pb-B Bonding in PbB 2 (BO) n - ( n = 0-2): Transformation from Aromatic PbB 2 - to Pb[B 2 (BO) 2 ] -/0 Complexes with BB Triple Bonds

Boron has been found to be able to form multiple bonds with lead. To probe Pb-B bonding, here we report an investigation of three Pb-doped boron clusters, PbB , PbB O , and PbB O , which are produced by a laser ablation cluster source and characterized by photoelectron spectroscopy and calculations. The most stable structures of PbB , PbB O , and PbB O are found to follow the formula, [PbB (BO) ] ( = 0-2), with zero, one, and two boronyl ligands coordinated to a triangular and aromatic PbB core, respectively. The PbB cluster contains a BB double bond and two Pb-B single bonds. The coordination of BO is observed to weaken Pb-B bonding but strengthen the BB bond in [PbB (BO) ] ( = 1, 2). The anionic [PbB (BO) ] and its corresponding neutral closed-shell [PbB (BO) ] contain a BB triple bond. A low-lying Y-shaped isomer is also observed for PbB O , consisting of a central sp hybridized B atom bonded to two boronyl ligands and a PbB unit.