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Chemistry of low-valent osmium

by Grundy, Kevin Rodger

Abstract (Summary)
This study concerns the synthesis, structure and reactivity of complexes of d? and d? osmium. The reactivity of certain ligands coordinated to low-valent osmium has also been investigated.

Various hydride complexes of osmium(II) were prepared as potential precursors of osmium(O). OsH?(PPh?)? reacts with p-tolylisocyanide (TIC) and 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane (ETPO) to yield OsH?(L)(PPh?)? from which were derived OsH?(L’)(L)(PPh?)? (L, L’=CO, TIC, ETPO).

Attempts to eliminate hydrogen from the dihydrides failed. OsHCl(CO) (PPh?)? reacts with neutral ligands L (=TIC, ETPO, P(OMe)?, P(OPh)?, PPh?Me) to give OsHCl(CO)(L)(PPh?)? which, with silver perchlorate (L=TIC, ETPO only) afford OsH(OClO?)(CO)(L)(PPh?)?. The labile perchlorate ligand can be replaced by ligands L’ affording [OsH(CO)(L)(L’)(PPh?)?]ClO4 (L=TIC, L’=CO, TIC, PPh? L=ETPO, L’=CO, ETPO). OsHCl(CO)(PPh?)? reacts with silver perchlorate in acetonitrile to yield [OsH(CO)(CH N)?(PPh?)?]ClO4, which in turn reacts with neutral ligands to give [OsH(CO)(CH?N)(L)(PPh?)?]ClO? (L=CO, TIC, ETPO, PPh?). Cationic [OsH(CO)?(PPh?)?]+ and [OsH(TIC)?(PPh?)?]+ can be prepared from the action of PPh? on [OsH(CO)?(CH?N)(PPh?)?]+ and TIC on OsH(O?CCH?)(PPh?)? respectively. With base, [OsH(CO)(CH?N)(PPh?)?]ClO4 affords OsH(OH)(CO)(PPh?)? from which a series of hydroxide complexes OsH(OH)(CO)(L)(PPh?)? (L=CO, TIC ETPO) can be obtained. The hydroxide group in OsH(OH)(CO)(PPh?)? is cleaved by acids HX to yield OsHX(CO)(PPh?)? (X=F, Br, Cl, I, CH?, CF?, SC?H?, OClO?). Those members of the series with X=CN, N?, OCN, SCN were obtained from OsH(OClO?)(CO)(PPh?)? and the appropriate anion. From the values of vCO for this series can be gained some understanding of the bonding properties of the anionic ligands.

Bibliographical Information:

Advisor:Associate Professor Warren Roper

School:The University of Auckland / Te Whare Wananga o Tamaki Makaurau

School Location:New Zealand

Source Type:Master's Thesis

Keywords:fields of research 250000 chemical sciences

ISBN:

Date of Publication:01/01/1975

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