619261-27-7

Upstream product

• 21205-91-4 9-borabicyclo[3.3.1]nonane dimer 
• 112320-11-3 (ruthenium)H2(bis-η2-dihydrogen)(PCy3)2 
• 181651-45-6 [RuH(η2-H2)((μ-H)2BC8H14)(tricyclohexylphosphine)2] 
• 280-64-8 9-bora-bicyclo[3.3.1]nonane 

Relevant academic research and scientific papers

9-BBN activation. Synthesis, crystal structure and theoretical characterization of the ruthenium complex Ru[(μ-H)2 BC8H14]2(PCy3)

Reaction of the bis(dihydrogen) ruthenium complex RuH2 (H2)2(PCy3)2 (1) with an excess of 9-borabicyclononane yields Ru[(μ-H)2 BC8H14]2(PCy3) (6) and the phosphine adduct PCy3·HBC8H14. The new complex is characterized by NMR spectroscopy and X-ray diffraction. New X-ray data on 9-BBN dimer, from a measurement at 180 K, are also reported. DFT calculations (B3LYP) on Ru[(μ-H)2 BC8H14]2(PMe3) (7), the PMe3 analogue of 6, confirm the ruthenium (II) formulation with two dihydroborate ligands. The data obtained using PH3 or PMe3 as models for PCy3 in PR3 ·HBC8H14 are also discussed.

Coordination modes of boranes in polyhydride ruthenium complexes: σ-borane versus dihydridoborate

The bis(dihydrogen) complex RuH2(η2-H 2)2(PCy3)2 (1) reacts at room temperature with 1 equiv of either HBpin or HBcat to produce the σ-borane complexes RuH2(η2-HBpin)(η2-H 2)-(PCy3)2 (2Bpin) and RuH2(η 2-HBcat)(η2-H2)(PCy3) 2 (2Bcat), respectively, by substitution of one σ-H2 ligand by one σ-B-H. In contrast, when using the 9-BBN reagent, the dihydridoborate complex RuH[(μ-H)2BBN](η2-H 2)(PCy3)2 (2BBN) is formed. The coordination modes of the borane ligands have been ascertained by NMR spectroscopy, X-ray diffraction, and theoretical studies (DFT/B3LYP). The results indicate that the dialkoxyborane ligands (HBpin and HBcat) are not acidic enough to stabilize a true symmetrical dihydridoborate coordination mode. They thus lead to σ-borane complexes presenting a small H/BH cis interaction between the boron atom and the adjacent hydride. The σ-H2 ligand in 2Bpin is located by X-ray diffraction at 90 K and found to be perpendicular to the equatorial plane. DFT calculations lead to the optimization of the two degenerate isomers RuH2[η2-HB(OCH2) 2]-(η2-H2)(PMe3)2 (5Bpin_a) (analogous to 2Bpin) and RuH[(μ-H)2B(OCH 2)2](η2-H2)(PMe 3)2 (5Bpin_b), demonstrating that σ-H2 rotation and σ-borane versus dihydridoborate ligation are intimately correlated. In contrast, the 9-BBN reagent is a strong Lewis acid and leads to a dihydridoborate complex. The theoretical study on RuH[(μ-H) 2Bpin](η2-HBpin)(PCy3)2 (3Bpin) shows that the bonding is also dependent on the hydride basicity: the RuH[(μ-H)2B(OCH2)2](PMe3) 2 fragment used as a model for RuH[(μ-H)2Bpin](PCy 3)2 is not basic enough to contain a second ligand bound in a dihydridoborate mode, despite the stabilization that should be gained from the resulting symmetrical structure.