Influence of the Cone Angles and the -Acceptor Properties of Phosphorus-Containing Ligands in the Chemistry of Dihydrogen Complexes of
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- 作者：Nisha Mathew ; Balaji R. Jagirdar ; R. Srinivasa Gopalan ; and G. U. Kulkarni
- 刊名：Organometallics
- 出版年：2000
- 出版时间：October 30, 2000
- 年：2000
- 卷：19
- 期：22
- 页码：4506 - 4517
- 全文大小：164K
- 年卷期：v.19,no.22(October 30, 2000)
- ISSN：1520-6041
文摘
A series of new dicationic dihydrogen complexes of ruthenium of the type trans-[(dppe)2Ru(
ta.gif" BORDER=0 >2-H2)(L')][BF4]2 (dppe = Ph2PCH2CH2PPh2; L' = PF(OMe)2, PF(OEt)2, PF(OiPr)2) have beenprepared by protonating the precursor hydride complexes trans-[(dppe)2Ru(H)(L')][BF4] usingHBF4·Et2O. The precursor hydride complexes have been obtained from trans-[(dppe)2Ru(H)(L)][BF4] (L = P(OMe)3, P(OEt)3, P(OiPr)3) via the substitution of a -OR group on thetrans phosphorus ligand with a fluoride in the presence of HBF4·Et2O. Coupling of thedihydrogen ligand with the trans phosphorus moiety has been observed. In addition to thecomplexes bearing trans phosphite groups, the precursor hydrides containing trans phosphineligands, viz., PMe3 and PMe2Ph, have also been prepared and characterized. It was foundthat the binding ability of the trans phosphorus ligand in both the hydride and dihydrogencomplexes decreases with an increase in the steric congestion of the trans phosphorus moiety.This indicates that the stability of this series of complexes depends on the cone angles ofthe trans phosphorus ligand. The protonation reactions of the hydride precursors trans-[(dppe)2Ru(H)(L)][BF4] (L = P(OMe)3, P(OEt)3, P(OiPr)3) (under certain experimentalconditions in the case of P(OiPr)3) result in mixtures of the new hydride complexes trans-[(dppe)2Ru(H)(L')][BF4] (L' = PF(OMe)2, PF(OEt)2, PF(OiPr)2) and the trans-[(dppe)2Ru(ta.gif" BORDER=0 >2-H2)(L')][BF4]2 derivatives. There is a strong dependence on the quantity of the acid used forthe isolation of either the new hydrides or the corresponding dihydrogen complexes. Bothdihydrogen and the new hydride complexes have been isolated and characterized. On theother hand, the protonation reactions of the starting hydrides that have trans-PMe3, PMe2Ph,or P(OiR)3 (under certain experimental conditions) ligands gave a hydride dihydrogencomplex, the structure formulation of which could not be established with certainty. Theroles of the steric as well as the 
-accepting properties of the trans phosphorus ligands inthis series of complexes are discussed. X-ray crystal structures of trans-[(dppe)2Ru(H)(P(OMe)3)][BF4], trans-[(dppe)2Ru(H)(PF(OMe)2)][BF4], and trans-[(dppe)2Ru(ta.gif" BORDER=0 >2-H2)(PF(OEt)2)][BF4]2 have been determined. trans-[(dppe)2Ru(H)(L)][BF4] (L = PMe3, PMe2Ph,P(OiPr)3) undergoes substitution of the trans phosphorus ligand with H2 to give trans-[(dppe)2Ru(H)(ta.gif" BORDER=0 >2-H2)][BF4] reversibly under very mild conditions.
ta.gif" BORDER=0 >2-H2)(L')][BF4]2 (dppe = Ph2PCH2CH2PPh2; L' = PF(OMe)2, PF(OEt)2, PF(OiPr)2) have beenprepared by protonating the precursor hydride complexes trans-[(dppe)2Ru(H)(L')][BF4] usingHBF4·Et2O. The precursor hydride complexes have been obtained from trans-[(dppe)2Ru(H)(L)][BF4] (L = P(OMe)3, P(OEt)3, P(OiPr)3) via the substitution of a -OR group on thetrans phosphorus ligand with a fluoride in the presence of HBF4·Et2O. Coupling of thedihydrogen ligand with the trans phosphorus moiety has been observed. In addition to thecomplexes bearing trans phosphite groups, the precursor hydrides containing trans phosphineligands, viz., PMe3 and PMe2Ph, have also been prepared and characterized. It was foundthat the binding ability of the trans phosphorus ligand in both the hydride and dihydrogencomplexes decreases with an increase in the steric congestion of the trans phosphorus moiety.This indicates that the stability of this series of complexes depends on the cone angles ofthe trans phosphorus ligand. The protonation reactions of the hydride precursors trans-[(dppe)2Ru(H)(L)][BF4] (L = P(OMe)3, P(OEt)3, P(OiPr)3) (under certain experimentalconditions in the case of P(OiPr)3) result in mixtures of the new hydride complexes trans-[(dppe)2Ru(H)(L')][BF4] (L' = PF(OMe)2, PF(OEt)2, PF(OiPr)2) and the trans-[(dppe)2Ru(ta.gif" BORDER=0 >2-H2)(L')][BF4]2 derivatives. There is a strong dependence on the quantity of the acid used forthe isolation of either the new hydrides or the corresponding dihydrogen complexes. Bothdihydrogen and the new hydride complexes have been isolated and characterized. On theother hand, the protonation reactions of the starting hydrides that have trans-PMe3, PMe2Ph,or P(OiR)3 (under certain experimental conditions) ligands gave a hydride dihydrogencomplex, the structure formulation of which could not be established with certainty. Theroles of the steric as well as the -accepting properties of the trans phosphorus ligands inthis series of complexes are discussed. X-ray crystal structures of trans-[(dppe)2Ru(H)(P(OMe)3)][BF4], trans-[(dppe)2Ru(H)(PF(OMe)2)][BF4], and trans-[(dppe)2Ru(ta.gif" BORDER=0 >2-H2)(PF(OEt)2)][BF4]2 have been determined. trans-[(dppe)2Ru(H)(L)][BF4] (L = PMe3, PMe2Ph,P(OiPr)3) undergoes substitution of the trans phosphorus ligand with H2 to give trans-[(dppe)2Ru(H)(ta.gif" BORDER=0 >2-H2)][BF4] reversibly under very mild conditions.