Synthesis and characterization of trinuclear osmium clusters containing diallylphosphines as hemilabile ligands: Experimental and theoretical studies of their reactivity with nucleophilic molecules

Abstract:

A series of [Os<inf>3</inf>(CO)<inf>12</inf>] phosphine substituted derivatives containing alkenylphosphine ligands has been synthesized starting from the cluster [Os<inf>3</inf>(CO)<inf>10</inf>(MeCN)<inf>2</inf>] and RP(CH<inf>2</inf>CHCH<inf>2</inf>)<inf>2</inf>where R = ⁱPr<inf>2</inf>N, o MeOC<inf>6</inf>H<inf>4</inf>or p-MeOC<inf>6</inf>H<inf>4</inf>. It was shown that the terminal alkenyl substituent in these phosphines undergoes coordination at the metal triangle to give the allyl fragment coordinated through the double bond. Solid-state structures of [Os<inf>3</inf>(CO)<inf>10</inf>{μ:κ³(P,C,C)-RP(CH<inf>2</inf>CCH<inf>2</inf>)<inf>2</inf>}] [R = ⁱPr<inf>2</inf>N (1a), o-MeOC<inf>6</inf>H<inf>4</inf>(1c)], [Os<inf>3</inf>(CO)<inf>10</inf>{κ¹(P)-ⁱPr<inf>2</inf>NP(CH<inf>2</inf>CCH<inf>2</inf>)<inf>2</inf>}L] [L = CO (3a), PPh<inf>3</inf>(4a)], [Os<inf>3</inf>(CO)<inf>9</inf>(PPh<inf>3</inf>){μ:κ³(P,C,C)-ⁱPr<inf>2</inf>NP(CH<inf>2</inf>CCH<inf>2</inf>)<inf>2</inf>}] (5a) and [Os<inf>3</inf>(CO)<inf>10</inf>(μ:η¹:η³-C<inf>3</inf>H<inf>4</inf>){κ¹(P)-p-MeOC<inf>6</inf>H<inf>4</inf>P(CH<inf>2</inf>CCH<inf>2</inf>)<inf>2</inf>}] (6b) were established by X-ray crystallography; all products obtained were also characterized by IR and NMR (¹H, ¹³C{¹H}, ³¹P{¹H}, ¹H-¹H and ¹H-¹³C correlations) spectroscopy. It was shown that [Os<inf>3</inf>(CO)<inf>10</inf>{μ:κ³(P,C,C)-(diallylphosphine)}] compounds in solution are present as a mixture of isomers; this isomerization is described as a reorientation of the coordinated double bond respect to the triosmium metal triangle. Also, reactivity studies were performed with CO, PPh<inf>3</inf>and C<inf>3</inf>H<inf>4</inf>, establishing the hemilabile properties of the diallyphosphine ligands with the cleavage of the allyl π-coordination when the nucleophilic molecules are CO and PPh<inf>3</inf>; in contrast, the nucleophile C<inf>3</inf>H<inf>4</inf>leads to cleavage and insertion of the allene into the Os-Os bond.

Año de publicación:

2014

Keywords:

• Hemilabile phosphines
• Triosmium carbonyls
• Allene insertion
• Diallylphosphines

Fuente:

scopus