A dinuclear phosphite rhodium(I) complex obtained by syngas treatment of a Rh/hydroxy phosphonite olefin hydroformylation precatalyst

A hydroxy phosphonite was found to be unstable during the catalyst preformation routine applied towards a rhodium olefin hydroformylation catalyst. C—P bond cleavage occurred when the phosphonite was reacted with [(acac)Rh(1,5-COD)] (acac is acetyl acetate and 1,5-COD is cycloocta-1,5-diene) at 80 °C and 20 bar of CO/H2. As a result, a nearly planar six-membered ring structure consisting of two rhodium(I) cations and two bridging phosphorous acid diester anions was formed, namely bis[μ-(4,8-di-tert-butyl-2,10-dimethoxydibenzo[d,f][1,3,2]dioxaphosphepin-6-yl)oxy]-1:2κ2 P:O;1:2κ2 O:P-bis{[6-([1,1′-biphenyl]-2-yloxy)-4,8-di-tert-butyl-2,10-dimethoxydibenzo[d,f][1,3,2]dioxaphosphepine-κP]carbonylrhodium(I)} toluene tetrasolvate, [Rh2(C22H28O5P)2(C34H37O5P)2(CO)2]·4C7H8. Further coordination of phosphite and of carbonyl groups resulted in 16-electron rhodium centres.

Synthesis of C2-Symmetric Diphosphormonoamidites and Their Use as Ligands in Rh-Catalyzed Hydroformylation: Relationships between Activity and Hydrolysis Stability

A series of diphosphoramidites has been synthetized with a piperazine, homopiperazine, and an acyclic 1,2-diamine unit in the backbone. New compounds were tested alongside related N-acyl phosphoramidites as ligands in the Rh-catalyzed hydroformylation of n-octenes to investigate their influence on the activity and regioselectivity. A subsequent study of their hydrolysis stability revealed that the most stable ligands induced the highest activity in the catalytic reaction.

Tetrakis(μ-benzoato-κ2O:O′)bis[(piperidine-κN)rhodium]

The title compound, [Rh2(C7H5O2)4(C5H11N)2], an adduct of dimeric rhodium(II) benzoate with piperidine, was prepared. The complex lies across an inversion centre with the unique RhIIion in a slightly distorted octahedral coordination environment.

{2-[Bis(2,4-di-tert-butylphenoxy)phosphanyloxy-κP]-3,5-di-tert-butylphenyl-κC1}{3,3′-di-tert-butyl-5,5′-dimethoxy-2,2′-bis[(1,1,2,2-tetraphenylethane-1,2-dioxy)phosphanyloxy-κP]biphenyl}rhodium(I) toluene-d82.7-solvate

The molecule of the title compound, [Rh(C42H62O3P)(C74H68O4P2]·2.7C7D8, consists of two phospharhodacyclic substructures sharing the Rh atom, which are formed by coordination/ortho-metallation of a triaryl phosphite, and by the coordination of a rigid bisphosphite, respectively. The metal displays a tetrahedrally distorted square-planar coordination geometry. Atert-butyl group shows rotational disorder over two positions with refined site occupancy of 0.561 (3):0.439 (3). Two partial-occupancy toluene solvent molecules are disordered over two orientations with site occupancies of 0.5:0.3 and 0.5:0.4, respectively. Intramolecular C—H...O hydrogen bonds are observed. In the crystal, complex molecules and toluene solvent molecules pack as alternating layers parallel to theacplane.

On the ambiguity of the reaction rate constants in multivariate curve resolution for reversible first-order reaction systems

If for a chemical reaction with a known reaction mechanism the concentration profiles are accessible only for certain species, e.g. only for the main product, then often the reaction rate constants cannot uniquely be determined from the concentration data. This is a well-known fact which includes the so-called slow-fast ambiguity. This work combines the question of unique or non-unique reaction rate constants with factor analytic methods of chemometrics. The idea is to reduce the rotational ambiguity of pure component factorizations by considering only those concentration factors which are possible solutions of the kinetic equations for a properly adapted set of reaction rate constants. The resulting set of reaction rate constants corresponds to those solutions of the rate equations which appear as feasible factors in a pure component factorization. The new analysis of the ambiguity of reaction rate constants extends recent research activities on the Area of Feasible Solutions (AFS). The consistency with a given chemical reaction scheme is shown to be a valuable tool in order to reduce the AFS. The new methods are applied to model and experimental data.

Carbonyl{3,3′-di-tert-butyl-5,5′-dimethoxy-2,2′-bis[(4,4,5,5-tetramethyl-1,3,2-dioxaphospholan-2-yl)oxy]biphenyl-κ2P,P′}hydrido(triphenylphosphane-κP)rhodium(I) diethyl ether trisolvate

In the title compound, [RhH(C₇₄H₆₈O₈P₂)(C₁₈H₁₅P)(CO)]·3C₄H₁₀O, the CHP₃ coordination set at the Rh^I ion is arranged in a distorted trigonal–bipyramidal geometry with the P atoms adopting equatorial coordination sites and the C atom of the carbonyl ligand as well as the H atom adopting the axial sites. The asymmetric unit contains two very similar mol­ecules of the rhodium complex, two half-occupied diethyl ether mol­ecules and further diethyl ether solvent mol­ecules which could not be modelled successfully. Therefore contributions of the latter were removed from the diffraction data using the SQUEEZE procedure in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155].

Dicarbonyl-{3,3'-di-tert-butyl-5,5'-di-meth-oxy-2,2'-bis-[(4,4,5,5-tetra-phenyl-1,3,2-dioxa-phospho-lan-2-yl)-oxy-κP]biphen-yl}hydridorhodium(I) diethyl ether monosolvate

In the title compound, [Rh(C₇₄H₆₈O₈P₂)H(CO)₂]·C₄H₁₀O, the C₂HP₂ coordination set at the Rh^I ion is arranged in a distorted trigonal–planar geometry with one P atom of the diphosphite mol­ecule and the H atom adopting the axial coordination sites.

{2-[Bis(2,4-di-tert-butyl-phen-oxy)phosphan-yloxy-κP]-3,5-di-tert-butyl-phenyl-κC}[(1,2,5,6-η)-cyclo-octa-1,5-diene]rhodium(I) toluene monosolvate

The reaction of (η³-all­yl)[(1,2,5,6-η)-cyclo­octa-1,5-diene]rhodium(I) with tris­(2,4-di-tert-butyl­phen­yl)phosphite in toluene produces the title compound, [Rh(C₄₂H₆₂O₃P)(C₈H₁₂)]·C₇H₈, by spontaneous metallation at one of the nonsubstituted phenyl ortho-C atoms of the phosphite mol­ecule. The coordination geometry at the Rh^I ion is distorted square-planar. The toluene solvent mol­ecule is disordered over two different orientations, with site-occupation factors of 0.810 (2) and 0.190 (2).