Unique Nido exo-archno equilibrium involving [(PPh{sub 3}){sub 2}(CO)OsB{sub 5}H{sub 9}] and its base adducts: Crystal and molecular structure of [[C@(PPh{sub 3}){sub 2}(CO)OsB{sub 4}H{sub 7}](BH{sub 2}. @PPh{sub 2}Me)]
- Univ. of Missouri, St. Louis, MO (United States)
Electron-counting rules for clusters allow predictions to be made about structural changes that result from the addition of electron pairs to cluster molecules. The anticipated effect is that addition of electron pairs to a cluster results in the opening up of the structure in the sequence closo, nido, arachno, hypho. There are some simple examples in the literature of systems in which addition of an electron pair to a small nido-borane, in the form of an equivalent of Lewis base, forms a conventional arachno-cluster. This results when CN{sup -} is added to B{sub 5}H{sub 9}. In most of the known cases, however, two electron pairs are added to the nido-borne to afford a hypho-cluster or the added base cleaves the borane. The structurally characterized adduct species include B{sub 5}H{sub 9}.2PMe{sub 3}, B{sub 4}H{sub 8}.(Me{sub 2}NCH{sub 2}){sub 2}, B{sub 5}H{sub 9}.(Ph{sub 2}P){sub 2}CH{sub 2}, B{sub 5}H{sub 9}.(Ph{sub 2}PCH{sub 2}){sub 2}, B{sub 5}H{sub 9}.(Me{sub 2}NCH{sub 2}){sub 2}, and B{sub 6}H{sub 10}.2PMe{sub 3}. In addition, B{sub 6}H{sub 10}.PMe{sub 3} has also been indentified from spectroscopic data. This paper describes the formation of a unique exo-arachno cluster, from the addition of phosphine bases to [(PPh{sub 3}){sub 2}(CO)OsB{sub 5}H{sub 9}] (1), in a process which is reversible. 20 refs., 1 fig.
- DOE Contract Number:
- FG02-92CH10499
- OSTI ID:
- 458605
- Journal Information:
- Journal of the American Chemical Society, Vol. 119, Issue 3; Other Information: PBD: 22 Jan 1997
- Country of Publication:
- United States
- Language:
- English
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