115141-03-2Relevant academic research and scientific papers
Evidence for the Lability of a Bridging Phosphido Ligand under Hydrogen Atmosphere. Reactions of the Cluster Complex Ru3(μ3-P(C6H5)(C5H4N))(μ-P(C6H5)2(CO)8
Lugan, Noel,Lavigne, Guy,Bonnet, Jean-Jacques,Reau, Regis,Neibecker, Denis,Tkatchenko, Igor
, p. 5369 - 5376 (2007/10/02)
In studies to determine free organic molecules that can be derived from the coordinated acyl group of the prototype complex Ru3(μ-C(O)(C6H5))(μ3-P(C6H5)(C5H4N))(CO)9 (1) or its PR2H substituted derivatives Ru3(μ-C(O)(C6H5))(μ3-P(C6H5)(C5H4N))(CO)8(PR2H) (2a, R = C6H5; 2b, R = C6H11), the species Ru3(μ3-P(C6H5)(C5H4N))(μ-PR2)(μ-CO)2(CO)6 (4a, R = C6H5; 4b, R = C6H11) are respectively obtained in 80percent and 65percent yield through a mild thermolysis of 2 where coordinated PR2H is the source of the hydrogen atom releasing benzaldehyde.Benzene is the only organic product obtained from the reaction of 1 with H2, producing Ru3(μ-H)(μ3-P(C6H5)(C5H4N))(CO)9 (3).By contrast, treatment of 1 with yields benzaldehyde and the salt 3-P(C6H5)(C5H4N))(CO)9 ().The high reactivity of 4a is first illustrated by a facile CO addition at 25 deg C involving metal-metal bond opening to give the 50-e cluster Ru3(μ3-P(C6H5)(C5H4N))(μ-P(C6H5)2(CO)9 (5a) (yield, 95percent).The addition of CO is reversible under reduced pressure or under a stream of argon at 25 deg C.Facile ligand substitutions from 4a are exemplified by two reactions.With triphenylphosphine, Ru3(μ3-P(C6H5)(C5H4N))(μ-P(C6H5)2(μ-CO)2(CO)5(P(C6H5)3) (6a) is produced in 80percent yield.Reaction of 4a with P(C6H5)2H, by contrast, gives Ru3(μ-H)(μ3-P(C6H5)(C5H4N))(μ-P(C6H5)2)2(CO)6 (7a) (yield, 65percent), which exists in two isomeric forms 7a1 (symmetric) and 7a2 (asymmetric).The latter complex is formed by rapid oxidative addition of P-H bond of P(C6H5)2H to the metal, following its initial coordination.Addition of hydrogen to the title complex 4a (tetrahydrofuran; P(H2), 40 bar; 120 deg C; 2 h) promotes the conversion of the bridging phosphido group μ-P(C6H5)2 into a terminal P(C6H5)2H ligand to produce Ru3(μ-H)(μ3-P(C6H5)(C5H4N))(CO)8(P(C6H5)2H) (8a) as the major product (yield, ca. 30percent), along with three additional species identified as 3, 7a1 and 7a2.Of these complexes, 8a is reconverted to 4a by heating under nitrogen.The formation of 3, 7a1 and 7a2 bears evidence of a hydrogen assisted intermolecular redistribution of phosphido groups.All complexes are characterized by elemental analysis, infrared spectroscopy, and 1H and 31P NMR.Details of the X-ray structures of 4b, 5a, and 6a are reported.The complex 4a is a catalyst precursor for the hydrogenation of cyclohexanone (typical experiment: tetrahydrofuran, 20 mL; 4a, 5E-2 mmol; cyclohexanone, 20 mmol; P(H2), 40 bar; 120 deg C; reaction time, 2h; yield, 77percent; turnover, 151).
