Multifunctional Ruthenium Catalysts:  A Novel Borohydride-Stabilized Polyhydride Complex Containing the Basic, Chelating Diphosphine 1,4-Bis(dicyclohexylphosphino)butane and Its Application to Hydrogenation and Murai Catalysis

Abstract

RuCl 2 (dcypb)(CO)] 2 2 (dcypb ) 1,4-bis(dicyclohexylphosphino)butane) was prepared in high yield via phosphine exchange between dcypb and RuCl 2 (CO)(PPh 3 ) 2 (DMF) (1). Reaction of 2 with 8 equiv of KBH s Bu 3 affords [fac-RuH 3 (CO)(dcypb)] -(3), stabilized by interactions with a K + counterion and an intact KBH s Bu 3 molecule in the third coordination sphere. Substantial ion pairing accounts for the stability and high hydrocarbon solubility of 3. Complex 3 effects reduction of benzophenone under unprecedentedly mild conditions, at 1 atm of H 2 in refluxing 2-propanol. It is also active for ortho functionalization of benzophenone under 20 atm of ethylene. Stoichiometric experiments reveal facile formation of orthometalated RuH(CO)[OC(C 6 H 4 )(Ph)](dcypb) (5), an intermediate proposed in both types of catalysis. The catalytic activity of isolated 5 supports this hypothesis in the case of hydrogenation but not of Murai catalysis. The X-ray crystal structures of 3 and 5 are reported.

Metal‐Hydride Bonding in Higher Alkali Metal Boron Monohydrides

“…Hence, monomeric {4,6-tBu 2 C 6 H 4 -(CMe 2 CH 2 -2)BH(C 5 H 4 )}{CpMo(H) 2 }Li·TMEDA, [32] dimeric {(DMPE) 2 MoH(NO)·Et 3 BHLi} 2 (DMPE = bis(dimethylphosphanyl)ethane), [33] and polymeric {(DMPE) 2 -Mo(NO) 2 ·Et 3 BHLi} ϱ [34] all reveal B(µ-H)Li components, while (DMPE) 2 TaH 3 (µ-H) 2 ·Et 3 BHLi incorporates a core Ta(µ-H) 2 Li metallocycle linked to a B(µ-H)Li unit, [35] and {(DCHPB) 2 Ru(µ-H) 3 ·(s-Bu) 3 BHK} 2 {DCHPB = bis(dicyclohexylphosphanyl)butane} reveals both Ru(µ-H) 3 K and B(µ-H)K 2 motifs peripheral to a (KO) 2 core. [36] Core metallocycles of the type noted in (3) 2 and (4) 2 {that is K(µ-H) 2 K}, have been suggested previously only in the non-trivial 9-borafluorenyl "ate" dimer of 1-mesityl-5,7,9-trimethyl-9-hydro-9-borafluorenyl potassium that results from the reduction of 2,6-Mes 2 C 6 H 3 BBr 2 by KC 8 and also in the B-B-bonded diborate bis{1-(Trip-5,7-diisopropyl-9-hydro-9-borafluorenyl)}bis(potassium) that results from the comparable treatment of 2,6-Trip 2 C 6 H 3 BBr 2 . [21] In each of these two instances, the dimeric aggregates have been extensively supported by inter-monomer arene stabilization of the metal centers.…”

Improved Syntheses of Versatile Ruthenium Hydridocarbonyl Catalysts Containing Electron‐Rich Ancillary Ligands

“…6 h by using triethylamine to take up the HCl produced, this modification affording 2 in 80% yield. [7] The dominant method in current use, reported by Yi and coworkers in 1999, [28] H} NMR singlets at 35.2 and 27.2 ppm, [29] respectively, accompanying the singlet for 2 at 46.9 ppm (Table 1). Group 8 metal complexes have long been known to undergo carbonylation [30] in alcohol solvents at elevated temperatures, although the extent varies, in part owing to competing thermal decarbonylation of polycarbonyl products.…”

Combinatorial Synthesis of Bimetallic Complexes with Three Halogeno Bridges

“…(R= Me, Et, iPr), [27] [{(dcypb)(CO)RuCl 2 } 2 ], [28] [RuCl 2 (CH 3 CN) 2 (PPh 3 ) 2 ], [29] [RuCl 2 (PhCN) 2 (dppb)], [18] [(dppb)ClRu-(m-Cl) 2 (m-OH 2 )RuCl(dppb)], [19] [(dcypb)(N 2 )Ru(m-Cl) 3 RuCl(dcypb)], [20] [(PPh 3 ) 2 ClRu(m-Cl) 2 (m-PhNHCHO-O,O)RuCl(PPh 3 ) 2 ], [16] and [(PPh 3 ) 2 ClRu(m-Cl) 3 Ru(acetone)(PPh 3 ) 2 ]…”