Collect. Czech. Chem. Commun. 1999, 64, 927-937

Isolation and Structure of [(PPh3)3(PPh2)2Pd4B20H16]. A Possible Prognostic for New Globular Borane-Based Cluster Architectures

Hai-Jun Yaoa, Chun-Hua hub, Jie Sunc, Ruo-Shui Jina, Pei-Ju Zhengb, Jonathan Bouldd, Robert Greatrexd, John D. Kennedyd,*, Daniel L. Ormsbyd and Mark Thornton-Pettd

a Department of Chemistry, Fudan University, Shanghai 200433, P. R. China
b Research Center of Analysis and Measurement, Fudan University, Shanghai 200433, P. R. China
c Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. China
d School Of Chemistry, University of Leeds, Leeds LS2 9JT, England


A novel metallaborane compound, [(PPh3)3(PPh2)2Pd4B20H16], prepared from [PdCl2(PPh3)2] and [B10H10]2- in EtOH, exhibits a globular cluster architecture consisting of two twelve-vertex closo {PdB11} cluster units fused to generate a condensed globular {PdB20} assembly that has a tetrahedral {B4} borons-only core. There is dynamic bonding between this borane-based assembly and an unusual exopolyhedral palladium-based domain consisting of a {(PPh3)Pd(PPh2)Pd(PPh2)Pd(PPh3)} string. The central tetrahedral borons-only core suggests a new type of globular "megaloborane" architectural principle for higher condensed boron hydrides, which is assessed by ab initio studies at the STO-3G level on protonated [B28H18]2- and related structures: results suggest energetic minimisation at neutral [B27H21].

Keywords: Boranes; Metallaboranes; Palladium-boron clusters; X-Ray crystallography; NMR spectroscopy; Large "megaloborane" polyhedral clusters; Ab initio calculations.