The electronic effect in the rhodium diphosphine catalyzed hydroformylation was investigated. A series of electronically modified thixantphos ligands was synthesized, and their effects on coordination chemistry and catalytic performance were studied. Phosphine basicity was varied by using p-(CH3)2N, p-CH3O, p-H, p-F, p-Cl, or p-CF3 substituents on the diphenylphosphine moieties. X-ray crystal structure determinations of the complexes (thixantphos)Rh(CO)H(PPh3) and (p-CH3O-thixantphos)Rh(CO)H(PPh3) were obtained. The solutions structures of the (diphosphine)Rh(CO)H(PPh3) and (diphosphine)Rh(CO)2H complexes were studied by IR and NMR spectroscopy. IR and 1H NMR spectroscopy showed that the (diphosphine)Rh(CO)2H complexes consist of dynamic equilibria of diequatorial (ee) and equatorial−apical (ea) isomers. The equilibrium compositions proved to be dependent on phosphine basicity; the ee:ea isomer ratio shifts gradually from almost one for the p-(CH3)2N-substituted ligand to more than nine for the p-CF3-substituted ligand. Assignments of bands to ee and ea isomers and the shifts in wavenumbers in the IR spectra were supported by calculations on (PH3)2Rh(CO)2H, (PH3)2Rh(CO)2D, and (PF3)2Rh(CO)2H complexes using density functional theory. In the hydroformylation of 1-octene and styrene an increase in l:b ratio and activity was observed with decreasing phosphine basicity. Most remarkably for 1-octene the selectivity for linear aldehyde formation was between 92 and 93% for all ligands. These results indicate that the chelation mode in the (diphosphine)Rh(CO)2H complexes per se is not the key parameter controlling the regioselectivity. Mechanistic explanations of the effect of the natural bite angle on regioselectivity are reconsidered.

Reaction of a rhodium(III)-a-chlorotolyl complex with water and with oxygen; Stable rhodium-peroxo compounds Haarman, H.F.; Bregman, F.R.; van Leeuwen, P.W.N.M.; Vrieze, K.

Reactions of [RhCl(diene)]2 (diene=NBD,COD) with bi-and terdentate nitrogen ligands. X-ray structures of five-coordinate complexes Haarman, H.F.; Bregman, F.R.; Ernsting, J.M.; Veldman, N.; Spek, A.L.; Vrieze, K. Published in: Organometallics DOI:10.1021/om960760bLink to publication Citation for published version (APA):Haarman, H. F., Bregman, F. R., Ernsting, J. M., Veldman, N., Spek, A. L., & Vrieze, K. (1997). Reactions of [RhCl(diene)]2 (diene=NBD,COD) with bi-and terdentate nitrogen ligands. X-ray structures of five-coordinate complexes. Organometallics, 16, 54-67. DOI: 10.1021/om960760b General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Reaction of [RhCl(diene)] 2 (diene ) 1,5-cyclooctadiene (COD) or bicyclo[2.2.1] hepta-2,5-diene (NBD)) with the N-N-N nitrogen ligands 2,6-(C(R 1 )dN-R 2 ) 2 C 5 H 3 N in CD 2 Cl 2 or CH 2 Cl 2 yielded the five-coordinate complexes [RhCl(2,6-(C(H)dN-R 2 ) 2 C 5 H 3 N)(diene)] (diene ) NBD; R 2 ) i- Pr, t-Bu, and p-anisyl), which has been isolated for NBD but not for COD. A single-crystal X-ray determination showed that [RhCl(2,6-(C(H)dN-p-anisyl) 2 C 5 H 3 N)(NBD)] has a distorted trigonal bipyramidal configuration with the pyridyl N-atom, one imine N-atom, and one alkene double bond in the equatorial plane, while the second alkene bond and the chloride atom occupy the axial positions. This conformation containing one noncoordinated imine moiety is clearly retained at 183 K in CD 2 Cl 2 , as is also the case for the other complexes. For the COD complexes, the reaction is more complicated, as the intermediates that are observed depend on the substituents R 1 and R 2 of the N-N-N nitrogen ligand. The five-coordinate complexes [RhCl(2,6-(C(R 1 )dN-R 2 ) 2 C 5 H 3 N)(COD)] could be observed at low temperatures for R IntroductionRecently we reported novel Rh(I) complexes which were able to cleave C-Cl bonds of reagents such as dichloromethane, chloroform, benzyl chloride, and R,Rdichlorotoluene by oxidative addition. 1 By employment of N-N-N nitrogen ligands of the type 2,6-(C(R 1 )dN-R 2 ) 2 C 5 H 3 N (R 1 ) H, R 2 ) i-Pr, t-Bu, cyclohexyl, and p-anisyl; R 1 ) Me, R 2 ) p-anisyl and i-Pr), we succeeded in preparing very nucleophilic and very reactive Rh(I) complexes via reaction of [RhCl(alkene) 2 ] 2 (alkene ) cyclooctene or...