Riitta H. Laitinen

M(CO)6 (M=Cr, Mo, W) derivatives of (o-anisyl)diphenylphosphine, bis(o-anisyl)phenylphosphine tris(o-anisyl)phosphine and (p-anisyl)bis(o-anisyl)phosphine

Abstract Aromatic tertiary phosphine ligands having ortho -methoxy substituents reacted with Group 6 metal carbonyls to form complexes with monodentate bonding through the phosphorus atom. One tungsten hexacarbonyl derivative with two P-bonded phosphine ligands was also formed. The complexes were characterized by X-ray crystallography, 1 H, 13 C{ 1 H} and 31 P{ 1 H) NMR spectroscopy, IR spectroscopy and elemental analysis. The steric properties of the ligands were studied by molecular modelling methods. Metal–phosphorus bond distances correlate with cone angles of the phosphines.

Organometallic derivatives of multidentate phosphines [o-(methylthio)phenyl]diphenylphosphine and bis(o-(methylthio)phenyl(phenylphosphine: preparation and characterization of group 6 metal carbonyl derivatives

Heterodonor phosphines [ o -(methylthio)phenyl]diphenylphosphine and bis[ o -(methylthio)phenyl]phenylphosphine react with group 6 metal carbonyls to form chelate complexes with bidentate bonding through P and S atoms. Only Cr(CO) 6 forms also monodentate derivative with [ o -(methylthio)phenyl]diphenylphosphine. The complexes are characterized by X-ray crystallography, 1 H-, 13 C-{ 1 H} and 31 P-{ 1 H}-NMR spectroscopy, IR spectroscopy, and elemental analyses.

Hydroformylation of 1-hexene and propene with in situ formed rhodium phosphine catalysts

A series of triphenylphosphines modified with different heteroatom groups (‐SCH 3, ‐N(CH3)2 ,‐ OCH 3, ‐CF3 )i northo or para position of the phenyl ring(s) were synthesised and tested for their catalytic behaviour in the rhodium catalysed hydroformylation of 1-hexene (80C, 15 bar) and propene (100C, 10 bar). Hydroformylation results for 1-hexene and propene differed markedly. With 1-hexene, the differences in activity and in chemo- and regioselectivity obtained with the various ligands were minor. Among the heterodonor ligands, the strong s-donor ligands yielded higher hydroformylation activity than the less basic ligands. In the case of propene, heterodonor bidentate ligands suppressed the hydroformylation reaction. In addition, 1,4-bis(diphenylphosphino)butane and (o-thiomethylphenyl)bis(1-naphthyl)phosphine favoured the formation of n-butanal. Only the ‐CF3 modified ligands behaved similarly with the two alkenes. The influence of the structure of the ligand in hydroformylation was studied by using molecular modelling methods. The steric size of the ab initio energy minimised free ligand structures was evaluated by Tolman’s cone angle method. Co-ordination properties of ‐CF 3 group modified phosphines were studied in reaction with Rh 2(CO)4Cl2, and the structure of Rh(CO)Cl(P(o-CF3C6H4)Ph2)2 (1 )w as determined crystallographically.

Hydroformylation of methyl methacrylate with heterodonor phosphinerhodium catalysts prepared in situ

The catalytic activity and selectivity of heterodonor phosphinerhodium catalysts prepared in situ were tested in the hydroformylation of methyl methacrylate at 100°C and 60 bar. Systematic variation of the heterodonor atom in the ortho position of the ligand showed that the heterodonor atom has a significant influence on the initial reaction rates and selectivities of the reaction. An exceptionally high selectivity to methyl‐α‐formylisobutyrate was observed with [o‐(methylthio)phenyl]diphenylphosphine ligand, which gave a branched to normal ratio of about 27. Study was also made of the product distribution during the experiment. The decrease in the branched to normal ratio was more severe with the diphosphine ligands than with the other heterodonor ligands.

SYNTHESES AND CHARACTERIZATION OF NEW TERTIARY PHOSPHANE LIGANDS PREPARED FROM P-ANISYL- AND P-THIOANISYLDICHLOROPHOSPHANES

The syntheses and spectroscopic parameters of the new tertiary phosphane ligands (p-MeOC6H4)(o-MeOC6H4)2P (1), (p-MeOC6H4)(o-MeSC6H4)2P (2), (p-MeSC6H4)(o-MeSC6H4)2P (3), (p-MeSC6H4)(o-MeOC6H4)2P (4), (p-MeOC6H4)(o-NC5H4)2P (5), and (p-MeSC6H4)(o-NC5H4)2P (6) are reported. Single-crystal X-ray structures of all the compounds (1–6) have been determined. The dependence of the 31P-NMR chemical shifts on the substituent groups of the phosphanes is discussed.

Multidentate phosphanes as ligands in rhodium catalyzed hydroformylation of 1-hexene

Abstract Triphenylphosphine derivatives modified with thiomethyl (SCH3) and methoxy (OCH3) groups in ortho- and para-position of the phenyl ring(s) were screened in situ Rh4(CO)12 catalyzed 1-hexene hydroformylation reaction. The effect of amount and position of the substituents on the hydroformylation results are discussed in terms of geometric and electronic properties of the ligands. The ab initio molecular modeling methods were used to calculate the ground state structures of the free ligands and their higher energy conformers. Cone angle calculations were used to evaluate the steric attributes of the calculated ligand structures. Additionally, study was made of the reactions between the methoxy substituted phosphanes and Rh2(μ-Cl)2(CO)4. The crystal structure of trans-Rh(CO)Cl(o-OOP)2 (1) is reported.

Aspects of regioselective control in the hydroformylation of methyl methacrylate with the in situ formed (o-thiomethylphenyl)diphenylphosphine rhodium complex

The regioselective control of the in situ formed ( o -thiomethylphenyl)diphenylphosphine ( o SP) rhodium catalyst was studied in methyl methacrylate (MMA) hydroformylation by changing the functionality of the triphenyl phosphine based ligands by systematically adding the possibility for multidentate binding, increasing the steric stress and modifying the electronic properties. Chelation control has a significant effect on the regioselectivity.

New Heterodonor Phosphine Ligands

Abstract In our studies we have synthesized three novel mixed ortho- and pura substituted phenyl phosphines: pSoOOP, pOoSSP and pSoSSP and a new phosphine containing pyridyl units: pS2Py. Also pOoOOP and pO2Py, which have been previously mentioned in patent literature[1,2] were prepared.