Synthesis and Reactivity of Ruthenium Arene Complexes Incorporating Novel Ph2PCH2CH2BR2 Ligands. Easy Access to the Four-Membered Ruthenacycle [(p-cymene)RuCl(κC,P-CH2CH2PPh2)]

• Published in: Organometallics Vol. 27; no. 6; pp. 1140 - 1146
• Main Authors: Vergnaud, Jérôme, Grellier, Mary, Bouhadir, Ghenwa, Vendier, Laure, Sabo-Etienne, Sylviane, Bourissou, Didier
• Format: Journal Article
• Language: English
• Published: American Chemical Society 24.03.2008
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om701139a

The ambiphilic ligands Ph2PCH2CH2BR2 (1a,b: BR2 = BCy2 (a), 9-BBN (b)) were readily prepared by hydroboration of vinyldiphenylphosphine. Reaction of 1a,b with [(p-cymene)RuCl2]2 afforded the corresponding complexes [(p-cymene)RuCl2(Ph2PCH2CH2BR2)] (2a,b), in which the borane moiety remains pendant, as confirmed by an X-ray diffraction analysis of 2b. Reaction of 2a,b with AgBF4 in the presence of acetonitrile leads to the formation of the corresponding cationic complexes [(p-cymene)RuCl(Ph2PCH2CH2BR2)(CH3CN)][BF4] (3a,b) without alteration of the pendant borane moiety. In contrast, treatment of 2a,b with AgOAc induces CH2−B bond cleavage and affords the four-membered ruthenacycle [(p-cymene)RuCl(κC,P-CH2CH2PPh2)] (4), characterized by X-ray diffraction. By reaction with chlorodicyclohexylborane, 4 gives back 2a via ring-opening σ-bond metathesis, whereas 4 reacts with chlorodiethylalane via alkylation at ruthenium with retention of the four-membered metallacycle to afford the ethyl complex [(p-cymene)RuEt(κC,P-CH2CH2PPh2)] (5).