An approach to megalo-boranes. Mixed and multiple cluster fusions involving iridaborane and platinaborane cluster compounds. Crystal structure determinations by conventional and synchrotron methods

Polyhedral Boron‐Containing Cluster Chemistry: Aspects of Architecture Beyond the Icosahedron

“…This series of diminishing hydrogen content exemplifies the concept that the increasing condensation associated with increasingly intimate cluster fusion is essentially an oxidative process [10]. The larger globular species also exhibit interesting surface phenomena, both intramolecular and intermolecular.…”

“…The central borons-only cores evident in XV and XVI lead to ideas that a future large globular boron-hydride family of "megaloboranes" would be based on central borons-only cores surrounded by a boron-hydride sheet or skin [10]. These "filled-ball" species would contrast to the "hollow-ball" fullerenes, in that the centers of the molecules would need to be full of boron atoms, and not hollow.…”

“…Following this idea, calculational examination of fragments of elemental boron lattices, with the peripheries of the fragments bound by hydrogen atoms, has revealed wells of stability that could represent future synthetic targets. These include the concept molecules B 27 H 21 and B 84 H 54 (Schematics XVII and XVIII) [9,10].…”

“…The larger globular species also exhibit interesting surface phenomena, both intramolecular and intermolecular. Examples of intramolecular surface effects include the restricted rotation of the {PMe 3 } units on the iridium atom that is held in a surface crevice of the {B 18 [8,10], and the fluxionality of the {(PPh 3 )Pd(PPh 2 )Pd(PPh 2 )Pd(PPh 3 )} chain that snakes back and forth over the surface of the {PdB 20 2− anion. These last species exhibit close anion-anion sub-Van der Waals contact in the solid-state structures [12].…”

Nine-vertex metallaborane chemistry. Preparation and characterisation of [1,1,1-(PMe3)2H-isocloso-IrB8H7-8-X], where X = H or Cl

“…This is observed for the 11 B(4,5), 11 B(2,7) and 11 B(9) signals, but not for 11 B(8) and 11 B(3,6) at the NMR polarising field strengths used. In this regard it may be noted that DFT-GIAO calculations for both the cisoid and transoid isomers ( Table 2) show only very small differences in boron nuclear shieldings, and any manifestation of peak-doubling for the 11 B(8) and 11 [34,35]. Ultimately, it was found that the heating of 1b in a refluxing solution in xylene that also contained a six-fold excess of B 10 H 14 afforded [1,1,1-(PMe 3 ) 2 H-isocloso-IrB 8 H 8 ] 3b in yields of up to ca.…”