Rhodium tetrafluoroborate

Bis(l,5-cyclooctadiene)rhodium Tetrafluoroborate-(/ )-2,2 Bis(diphenyl-phosphino)- l,l -binaphthyP... 

Preparative Methods the ligand (3R,4R)-3,4-bis(di-phenylphosphino)-l-methylpyrrolidine (la) is prepared from L-tartaric acid via (3R,4R)-3,4-bis(diphenylphosphino)-1-benzylpyrrolidine (lb) as shown in eq 1. Tbe title cationic rhodium complex is made by mixing bis(l,5-cyclopentadiene)rhodium tetrafluoroborate and (la) in CH2CI2 under nitrogen. 

Bis(l,5-cyclooctadiene)rhodium Tetrafluoroborate-(P)-2,2 -Bis(diphenylphosphino)-1,1 -binaphthyl, 118 C16H24O... 

Triphenylmethyl tetrafluoroborate (2.98 g, 9.1 mmol) in dichloromethane (40 mL) was added dropwise to a solution of acetylacetonato(l,5-cyclooctadiene)rhodium (2.8 g, 9.1 mmol) and 1,5-cyclooctadiene (5 mL excess) in dichloromethane (20 mL) at 25 °C. The yellow solution turned deep red, and was then stirred for 5 min. The solution was added to diethyl ether (400 mL) and the resulting orange-red crystals of bis(cyclo-octa-l,5-diene)rhodium tetrafluoroborate (3.44 g, 94%) were collected. ... 

Bis(l,5-cyclooctadiene)rhodium tetrafluoroborate (1.4 g, 3.45 mmol) was dissolved in methylene chloride (20 mL), and acetonitrile (5 mL) was added dropwise to the stirred solution. The resultant yellow solution was added to diethyl ether (100 mL) to give bright yellow crystals of 6/5(acetonitrile)(l,5-cyclooctadiene)rhodium tetrafluoroborate (1.15 g, 88%). ... 

C30H44B2F80 Rh2, Bis[(pentamethylcyclopentadienyl)(2,4-pentanedion-ato)rhodium] tetrafluoroborate, 45B, 983 C3oHn6GeOP2Pt, cis-(Hydroxydiphenylgermyl)phenylbis(triethylphos-phine)platinum(II), 37B, 436... 

The rhodium and iridium complexes of dibenzothiophene (L) reveal an interesting case of linkage isomerism (91IC5046). Thus, the ti S) coordinated species [MCp LCb] on thermolysis with silver tetrafluoroborate afford the Ti -coordinated dicationic species. 

Manufacture of rhodium precatalysts for asymmetric hydrogenation. Established literature methods used to make the Rh-DuPhos complexes consisted of converting (1,5-cyclooctadiene) acetylacetonato Rh(l) into the sparingly soluble bis(l,5-cyclooctadiene) Rh(l) tetrafluoroborate complex which then reacts with the diphosphine ligand to provide the precatalyst complex in solution. Addition of an anti-solvent results in precipitation of the desired product. Although this method worked well with a variety of diphosphines, yields were modest and more importantly the product form was variable. The different physical forms performed equally as well in hydrogenation reactions but had different shelf-life and air stability. 

Hydroformylation of alkenes can be carried out in a few minutes under microwave activation at a relatively low pressure (2.7 bar) employing the rhodium(I)/XANTPHOS catalyst. The presence of the ionic liquid butyl-methylimdazolium tetrafluoroborate ([bmim][BF4]) was crucial. Unfortu-... 

This catalytic reaction was believed to proceed analogously to those with phenylboronic acids (Scheme 49) 137 137a Transmetallation of the arylstannane with the cationic rhodium complex generated the rhodium aryl species a and trimethyltin tetrafluoroborate. Conjugate addition generated rhodium enolate b, which subsequently reacted with... 

In a 25 mL Schlenk-type flask, equipped with a 10 mL pressure equalized dropping funnel and a magnetic stirring bar, were placed bis(l,5-cycloocta-diene)rhodium(I) tetrafluoroborate (111mg) and dichloromethane (5mL) under nitrogen. 

Common precursors for the enantioselective hydrogenation with the use of cationic rhodium are the tetrafluoroborate salts of bis-alkadiene rhodium. As a solvent one often uses dichloromethane or methanol, in which tetrafluoroborate is indeed weakly or non-coordinating. The first alkadiene at rhodium is rapidly replaced in situ by the phosphorus ligands added. 

Recently, the air- and water-stable combinations of l-n-butyl-3-methyl-imidazolium chloride with sodium tetrafluoroborate or sodium hexafluoro-phosphate have been prepared. The rhodium complexes [RhCl(PPh3)3] and [Rh(COD)2](BF4) are completely soluble in these ionic liquids and catalyze the hydrogenation of cyclohexene in a typical two-phase reaction with numbers of turnovers of up to 6000 (131). 

Diastereoselectivehydrogenation.3 The 8-hydroxy-a,p-unsaturated ester (3) undergoes hydrogenation in the presence of rhodium [(+ )-BINAP]-norbornadiene tetrafluoroborate (1) (10, 36) almost exclusively to give 4. This catalyst (1) is more effective than rhodium(DIPHOS)norbornadiene tetrafluoroborate (2) (12, 426). 

Aluminum chloride, 15 Arenediazonium tetrafluoroborates, 19 Rhodium(II) carboxylates, 266 Tris(dimethylamino)sulfonium difluoro-trimethylsilicate, 336 Asymmetric reactions Addition reactions to carbonyl groups Bis(2,4-dimethyl-3-pentyl) tartrate, 36 (S)-( + )-2-Methoxymethylpyrrolidine, 180... 

Sodium triacetoxyborohydride, 283 Titanium(III) chloride, 302 Tributyltin hydride, 316 Zinc borohydride, 167 of alkenes to alkanes (R)-(-F)- and (S)-(-)-2,2 -Bis(di-phenylphosphine)-l,1 -binaphthyl, 36 [1,4-Bis(diphenylphosphine)-butanej(cycloheptatriene)-rhodium(I) tetrafluoroborate, 89 [ 1,4-Bis(diphenylphosphine)butane]-(norbornadiene)rhodium(I) tetrafluoroborate, 37... 

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