908849-75-2Relevant academic research and scientific papers
Polyhedral iridaborane chemistry: Elements of the 10-vertex closo-isonido-isocloso continuum.
Bould, Jonathan,Clegg, William,Kennedy, John D.
, p. 3723 - 3735 (2008/10/09)
There is experimental difficulty in the isolation and structural definition of examples of compounds of the isonido 10-vertex cluster structure in order that they may be adduced to the pattern of behaviour associated with the 10-vertex closo-isonido-isocloso structural continuum in boron-containing cluster chemistry. By contrast, the closo and isocloso extremes are well recognised, with several definitive examples. An approach involving the synergic application of crystallography (using single-crystal X-ray diffraction analysis and HYDEX), multi-element NMR spectroscopy, and DFT calculations of structure and nuclear magnetic shielding, has been used to delineate and define two basic variants in the quadrilaterally open-faced 10-vertex 'isonido' {IrB9} metallaborane system. Type A variants, as in [7,7,7-(PPh3)2H-μ-3,7-H-isonido-7-IrB9 H8-9-(PPh3)] (2), have an Ir-H-B bridging hydrogen atom involving a boron atom off the open face, and an Ir-H non-bridging linkage. Type B variants, as in [8-Cl-7-(PPh3)-μ-7P,10C-(Ph2 P-ortho-C6H4)-isonido-7-IrB9H6 -9-(PPh3)] (5), have no cluster-bridging hydrogen atoms and no Ir-H unit. Previously unreported single-crystal X-ray diffraction analyses are given for isonido type-A [7-(PPh3)-μ-7P,10C-(Ph2P- ortho-C6H4)-7-H-μ-3,7-H-isonido-7-IrB9 H8-9-(PPh3)] (10), classical closo [7-(PPh3)-μ-7P,10C-(Ph2P- ortho-C6H4)-7-H-closo-7-IrB9H6 -3,9-(PPh3)2] (13) and classical nido [6-(PPh3)-μ-6P,5C-(Ph2P-o rtho-C6H4)-6-H-nido-6-IrB9H12 ] (15). Overall, the work well demonstrates the synergic usage of NMR spectroscopy, single-crystal X-ray crystallography (including HYDEX calculations) and DFT calculations of structure and nuclear shielding, to resolve ambiguous problems of chemical constitution in polyhedral boron-containing cluster chemistry, an approach that should have wider applicability.
