TY - JOUR
T1 - Bis(acetylacetonato)bis(cyclooctene)ruthenium(II), cis-[Ru(acac)2-(η2-C8H14) 2]
T2 - A synthetic precursor to trans- and cis-bis(acetylacetonato)ruthenium(II) complexes
AU - Bennett, Martin A.
AU - Chung, Guandolina
AU - Hockless, David C.R.
AU - Neumann, Horst
AU - Willis, Anthony C.
PY - 1999/10/7
Y1 - 1999/10/7
N2 - Reduction of [Ru(acac)3] with zinc amalgam or zinc dust in hot THF containing some water in the presence of an excess of cyclooctene generated in solution cis-[Ru(acac)2(η2-C8H14) 2], which cannot be isolated in solid form but has been identified on the basis of its 1H NMR spectrum. It is a useful synthetic precursor because the co-ordinated olefins are easily displaced by many ligands. Treatment with pyridine, tert-butyl isocyanide, tertiary phosphines, phosphites and triphenylarsine (L) at room temperature gave red-brown complexes trans-[Ru(acac)2L2], which isomerise in solution to the more stable cis compounds on heating. In contrast, the similarly prepared trimethylamine complex, trans-[Ru(acac)2(NMe3)2], does not undergo trans to cis isomerisation. Reaction of cis-[Ru(acac)2(η2-C8H14) 2] with acetonitrile or triphenylstibine (L′) gave monosubstitution products cis-[Ru(acac)2-(η2-C8H 14)L′], which react on heating with an excess of L′ to give cis-[Ru(acac)2L′2]. Treatment of cis-[Ru(acac)2-(η2-C8H14) 2] (1 mol) with Ph2PCH2PPh2 (dppm) (2 mol) at room temperature gave trans-[Ru(acac)2(ηI-dppm)2], whereas the ligands Ph2P(CH2)mPPh2 (L-L, m = 2, dppe; m = 3, dppp) under the same conditions gave oligomers [{Ru(acac)2(L-L)}n], which probably contain mutually trans-phosphorus atoms. On heating all three compounds are converted into cis-[Ru(acac)2(L-L)]. Treatment of trans-[Ru(acac)2L2] (L = NMe3 or PPh3) with CO at room temperature and pressure gave trans-[Ru(acac)2(CO)L], which, in the case of L = PPh3, isomerises to the cis compound on heating; reaction of trans-[Ru(acac)2(AsPh3)2] with CO under the same conditions gave cis-[Ru(acac)2(CO)(AsPh3)] directly. The structures of trans-[Ru(acac)2(CNBut)2], trans-[Ru(acac)2(PMePh2)2], cis-[Ru(acac)2(CNBut)2] (in the form of a molecular adduct with [Ru(acac)3]), cis-[Ru(acac)2(PMePh2)2] and trans-[Ru(acac)2(ηI-dppm)2] have been determined by X-ray crystallography, and trends in the metal-ligand distances are discussed. The formation of trans-[Ru(acac)2L2] from cis-[Ru(acac)2(η2-C8H14) 2] may proceed via a square-pyramidal intermediate [Ru(acac)2L].
AB - Reduction of [Ru(acac)3] with zinc amalgam or zinc dust in hot THF containing some water in the presence of an excess of cyclooctene generated in solution cis-[Ru(acac)2(η2-C8H14) 2], which cannot be isolated in solid form but has been identified on the basis of its 1H NMR spectrum. It is a useful synthetic precursor because the co-ordinated olefins are easily displaced by many ligands. Treatment with pyridine, tert-butyl isocyanide, tertiary phosphines, phosphites and triphenylarsine (L) at room temperature gave red-brown complexes trans-[Ru(acac)2L2], which isomerise in solution to the more stable cis compounds on heating. In contrast, the similarly prepared trimethylamine complex, trans-[Ru(acac)2(NMe3)2], does not undergo trans to cis isomerisation. Reaction of cis-[Ru(acac)2(η2-C8H14) 2] with acetonitrile or triphenylstibine (L′) gave monosubstitution products cis-[Ru(acac)2-(η2-C8H 14)L′], which react on heating with an excess of L′ to give cis-[Ru(acac)2L′2]. Treatment of cis-[Ru(acac)2-(η2-C8H14) 2] (1 mol) with Ph2PCH2PPh2 (dppm) (2 mol) at room temperature gave trans-[Ru(acac)2(ηI-dppm)2], whereas the ligands Ph2P(CH2)mPPh2 (L-L, m = 2, dppe; m = 3, dppp) under the same conditions gave oligomers [{Ru(acac)2(L-L)}n], which probably contain mutually trans-phosphorus atoms. On heating all three compounds are converted into cis-[Ru(acac)2(L-L)]. Treatment of trans-[Ru(acac)2L2] (L = NMe3 or PPh3) with CO at room temperature and pressure gave trans-[Ru(acac)2(CO)L], which, in the case of L = PPh3, isomerises to the cis compound on heating; reaction of trans-[Ru(acac)2(AsPh3)2] with CO under the same conditions gave cis-[Ru(acac)2(CO)(AsPh3)] directly. The structures of trans-[Ru(acac)2(CNBut)2], trans-[Ru(acac)2(PMePh2)2], cis-[Ru(acac)2(CNBut)2] (in the form of a molecular adduct with [Ru(acac)3]), cis-[Ru(acac)2(PMePh2)2] and trans-[Ru(acac)2(ηI-dppm)2] have been determined by X-ray crystallography, and trends in the metal-ligand distances are discussed. The formation of trans-[Ru(acac)2L2] from cis-[Ru(acac)2(η2-C8H14) 2] may proceed via a square-pyramidal intermediate [Ru(acac)2L].
UR - http://www.scopus.com/inward/record.url?scp=33749119818&partnerID=8YFLogxK
U2 - 10.1039/a905492h
DO - 10.1039/a905492h
M3 - Article
SN - 1470-479X
SP - 3451
EP - 3462
JO - Journal of the Chemical Society. Dalton Transactions
JF - Journal of the Chemical Society. Dalton Transactions
IS - 19
ER -