Chemistry of low-valent osmium

This study concerns the synthesis, structure and reactivity of complexes of d⁶ and d⁸ 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). OsH₄(PPh₃)₃ reacts with p-tolylisocyanide (TIC) and 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane (ETPO) to yield OsH₂(L)(PPh₃)₃ from which were derived OsH₂(L’)(L)(PPh₃)₂ (L, L’=CO, TIC, ETPO). Attempts to eliminate hydrogen from the dihydrides failed. OsHCl(CO) (PPh₃)₃ reacts with neutral ligands L (=TIC, ETPO, P(OMe)₃, P(OPh)₃, PPh₂Me) to give OsHCl(CO)(L)(PPh₃)₂ which, with silver perchlorate (L=TIC, ETPO only) afford OsH(OClO₃)(CO)(L)(PPh₃)₂. The labile perchlorate ligand can be replaced by ligands L’ affording [OsH(CO)(L)(L’)(PPh₃)₂]ClO4 (L=TIC, L’=CO, TIC, PPh₃ L=ETPO, L’=CO, ETPO). OsHCl(CO)(PPh₃)₃ reacts with silver perchlorate in acetonitrile to yield [OsH(CO)(CH𠠼N)₂(PPh₃)₂]ClO4, which in turn reacts with neutral ligands to give [OsH(CO)(CH₃N)(L)(PPh₃)₂]ClO₄ (L=CO, TIC, ETPO, PPh₃). Cationic [OsH(CO)₂(PPh₃)₃]+ and [OsH(TIC)₂(PPh₃)₃]+ can be prepared from the action of PPh₃ on [OsH(CO)₂(CH₃N)(PPh₃)₂]+ and TIC on OsH(O₂CCH₃)(PPh₃)₃ respectively. With base, [OsH(CO)(CH₃N)(PPh₃)₃]ClO4 affords OsH(OH)(CO)(PPh₃)₃ from which a series of hydroxide complexes OsH(OH)(CO)(L)(PPh₃)₂ (L=CO, TIC ETPO) can be obtained. The hydroxide group in OsH(OH)(CO)(PPh₃)₃ is cleaved by acids HX to yield OsHX(CO)(PPh₃)₃ (X=F, Br, Cl, I, CH₂, CF₂, SC₇H₇, OClO₃). Those members of the series with X=CN, N₃, OCN, SCN were obtained from OsH(OClO₃)(CO)(PPh₃)₃ 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.

Name thesis:degree_name

PhD

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Chemistry

Grantor dc:publisher

ResearchSpace@Auckland

Year dc:date.issued

1975

Author dc:creator

• Grundy, Kevin Rodger

Advisor dc:contributor.advisor

• Associate Professor Warren Roper

Statement dc:rights

• Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Licence dc:rights.uri

• https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/2292/2326

OAI identifier oai:identifier

oai:researchspace.auckland.ac.nz:2292/2326