Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School 2014 Improved Synthesis, Separation, Transition Metal Coordination and Reaction Chemistry of a New Binucleating Tetraphosphine Ligand Ekaterina Kalachnikova Louisiana State University and Agricultural and Mechanical College Follow this and additional works at: https://digitalcommons.edu/gradschool_dissertations Part of the Chemistry Commons Recommended Citation Kalachnikova, Ekaterina, "Improved Synthesis, Separation, Transition Metal Coordination and Reaction Chemistry of a New Binucleating Tetraphosphine Ligand" (2014). LSU Doctoral Dissertations.edu/gradschool_dissertations/1105 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Doctoral Dissertations by an authorized graduate school editor of LSU Digital Commons. For more information, please contactgradetd@lsu.
IMPROVED SYNTHESIS, SEPARATION, TRANSITION METAL COORDINATION AND REACTION CHEMISTRY OF A NEW BINUCLEATING TETRAPHOSPHINE LIGAND A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirement for the degree of Doctor of Philosophy in The Department of Chemistry by Ekaterina Kalachnikova B. University of South Alabama, 2007 May 2015 Acknowledgements I am very grateful to Prof. George Stanley for providing me with the opportunity to join his research group, for his guidance, encouragement, and constant support. Thank you for dedicating your time and energy to help me be an individual I am today.
Thank you for always being available and ready to help. I thank my doctoral committee members: Profs. Andrew Maverick, Evgueni Nesterov, Jun Xu for all their time and helpful suggestions. I am especially thankful to Dr.
Frank Fronczek and Dr. McCandless for their crystallographic expertise and willingness to explain how things work. I am very thankful to Dr. Dale Treleaven for his many helpful discussions, for introducing me to NMR, and for all the suggestions regarding this dissertation.
Thank you to Dr. Thomas Weldegheorghis for his NMR expertise and for all his help. I am forever thankful to Stanley group for helpful suggestions, fruitful discussions and friendships. ii Table of Contents Acknowledgements.
ii List of Tables. vi List of Figures. vii List of Schemes. xii List of Abbreviations.
xvi Chapter 1: Introduction .2 Mechanistic Aspects of Alkene Hydration Catalyzed by Late Transition Metal Complexes .3 Bimetallic Nickel Tetraphosphine Complexes as Possible Catalysts for Alkene Hydration/Oxidation .4 Alkene Oxidative Cleavage. 21 Chapter 2: Investigations into Alkene Hydration/Oligomerization by Nickel Phosphine Complexes: The Unfortunate Role of Rubber Septa .1 Review of Prior Research .2 Results and Discussion: Further Investigation into Ni oligomerization Catalysis. 35 Chapter 3: Nickel - Phosphine Mediated Oxidative Cleavage of Alkene C = C Bonds by O2.2 Results and Discussion .1 Investigations into Alkene Oxidation in the Presence of Ni(II) Phosphine Complexes.3 Synthesis and Characterization of meso-Ni2Br4(et,ph-P4) .4 Other Systems Tested .5 Other Reaction Observations. 48 Addition of AgBF4.
49 Other Organic Solvents Tested. 50 H2O2 as Primary Oxidant. 53 Investigations into the Nature of the Active Species. 53 Variable Temperature NMR.
57 Low Temperature NMR. 60 NMR Studies of the et, ph-P4 Ligand in Solution in the Presence of Oxygen .8 Oxidative Cleavage of Alkene in the Presence of Phosphine Ligands. 73 Chapter 4: New Tetraphosphine Ligand Synthesis, Separation, Transition Metal Coordination, and Characterization.2 Results and Discussion .1 Preparation of Cl(Ph)PCH2P(Ph)Cl, 2 .3 Preparation of rac,meso-et,ph-P4-Ph.4 Separation of rac and meso-Diastereomers of et,ph-P4-Ph .5 Improved Preparation of et,ph-P4-Ph Ligand via Grignard Mediated P-C Coupling .6 Synthesis of Pt2Cl4(rac-et,pt-P4-Ph), 4R .7 Synthesis of PtNiCl4(rac-et,pt-P4-Ph), 5R .3 Conclusions and Future Directions. 130 Chapter 5: Experimental Procedures and Additional Spectroscopic Data .2 General Procedure Used to Study Alkene Oligomerization Catalysis .3 General Procedure Used to Test for Alkene Hydration .4 Synthesis and Characterization of meso-Ni2Cl4(et,ph-P4) .5 General Procedure Used to Study Alkene Oxidative Cleavage Catalysis .6 Reaction of meso-Ni2Cl4(et,ph-P4) and 1-Hexene Monitored by Variable Temperature NMR .7 Variable Temperature NMR of the “final” Species .8 Synthesis of Methylenebis (Chlorophenylphosphine).11 Synthesis of rac,meso-et,ph-P4-Ph Ligand .12 Separation rac and meso-et,ph-P4-Ph via Column Chromatography .13 Synthesis of Pt2Cl4(rac-et,ph-P4-Ph), 4R .14 Synthesis of PtNiCl4(rac-et,ph-P4-Ph), 5R .16 Additional Spectroscopic Data.
156 v List of Tables Table 3.1 Crystallographic Data for meso-Ni2Br4(et,ph-P4)•2(CH3CN) .2 Selected Bond Distances (Å) and Angles (°) for meso-Ni2Br4(et,ph- P4)•2(CH3CN) .1 Chlorination of primary and secondary phosphines with C2Cl6 and PCl5 as reported by Weferling .2 Results from the chlorination of 2 with C2Cl6 and PCl5 .3 Preparation of arylphosphines via magnesium-halide exchange reaction of aryl halides with i PrMgBr, followed by reaction with PEt2Cl reported by Monteil.4 Selected Bond Distances (Å) and Angles (deg) for one molecule of rac Pt2Cl4(et,ph-P4-Ph) .5 Selected Bond Distances (Å) and Angles (deg) for rac-NiPtCl4(et,ph- P4-Ph)•CH2Cl2 .6 Selected Bond Distances (Å) and Angles (°) for [Rh2(nbd)2(rac- et,ph-P4 Ph)](BF4)2•2C3H6O. 127 vi List of Figures Figure 1.1 Binucleating tetraphosphine ligands rac- and meso-et,ph-P4 .2 Rac-Ni2Cl4(et,Ph-P4) and meso-Ni2Cl4(et,Ph-P4) .3 Binucleating tetraphosphine ligands rac- and meso-et,ph-P4-Ph .4 ORTEP plot of [Ni2Cl2(µ-OH)(meso-et,ph-P4-Ph)]+. Ni··Ni distance of 3.1 Gel permeation chromatography of the white solid produced from three reactions of 1-hexene, 1-octene, and a mixture of 1- hexene/1- octene and Ni2Cl4(meso-et,ph-P4) in a H2O/acetone solvent mixture (70°C) .2 FT-IR of the white solid produced from 1-hexene and Ni2Cl4(meso- et,ph-P4) in a H2O/acetone solvent mixture (70°C) compared to a C36H74 reference .3 (a) Nickel catalyst used by Keim to oligomerize ethylene to produce 1-alkenes of various chain lengths.1 (b) Ni(II) complexes used by Brookhart et al. in the presence of MAO (methylaluminoxane) as co-catalyst for ethylene polymerization.
R = i-Pr, R’ = H,Me, or 1,8-napthdiyl .4 400 MHz 1H NMR of white powder in CDCl3 from the reaction of 1- hexene in the presence of meso-Ni2Cl4(et,ph-P4) .5 400 MHz 1H NMR of white powder in CDCl3 Top: from the reaction of vinyl acetate in the presence of meso-Ni2Cl4(et,ph-P4) catalyst. Bottom: from the reaction of 1-hexene in the presence of meso- Ni2Cl4(et,ph-P4) catalyst .1 The 5-11 ppm region of the 1H NMR spectrum of the sample from the reaction of meso-Ni2Cl4(et,ph-P4) with 1-hexene in acetone-d6/D2O (15% by volume).5 ppm are due to the phenyl-ring hydrogens on the et-ph-P4 ligand .2 P{1H} spectrum of meso-Ni2Br4(et,ph-P4) in CD3CN. Solvent molecules and hydrogen atoms omitted for clarity .4 ORTEP plot of [Ni2(-OH)Cl2(et,ph-P4-Ph)], 2. Ellipsoids are shown at the 50% probability level.
Hydrogens on the carbon atoms and the [NiCl4]2 counter-anion are omitted for clarity .7 ppm region of the 1H NMR spectra: meso-Ni2Cl4(et,ph-P4) in acetone-d6; (red spectrum) D2O added, after 3 days under O2 .6 P{1H} spectra of meso-Ni2Cl4(et,ph-P4) in CD2Cl2 (red line). 31P{1H} spectra of meso - Ni2Cl4(et,ph-P4) in acetone-d6/D2O recorded 20 minutes after addition of D2O (green line). 31P{1H} spectra of meso- Ni2Cl4(et,ph-P4) in acetone-d6/D2O recorded 24 hours after addition of D2O (black line). 31P{1H} spectra of meso-Ni2Cl4(et,ph-P4) in acetone-d6/D2O recorded 2 days after addition of D2O (blue line) .7 P{1H} spectra of the sample taken from reaction with 1-hexene in the presence of meso-Ni2Br4(et,ph-P4) in in acetone-d6/D2O recorded 24 hours after the start of the reaction .8 ORTEP plot of [Ni2(µ-Cl)(meso-et,ph-P4)2]3+, (50% probability ellipsoids, hydrogen atoms omitted for clarity) .9 P{1H} spectra of meso-Ni2Cl4(et,ph-P4) with 1-hexene in acetone-d6/D2O recorded at 15°C (light blue), 10°C (dark blue), 25°C (black), 50°C (orange), 80°C (purple), and 100°C (red).
For higher temperatures the NMR tube was tube pressurized to 90 psi with O2 .10 H spectra of meso-Ni2Cl4(et,ph-P4) with 1-hexene in acetone-d6/D2O solution recorded at 100°C, tube pressurized 90 psi of O2 .11 P{1H} NMR spectra of meso-Ni2Cl4(et,ph-P4) in acetone-d6/D2O solution: a) at –20°, b) ‒20°, 1-hexene added, c) 5°C, d) 25°C.12 H spectra of meso-Ni2Cl4(et,ph-P4) in acetone-d6/D2O solution: a) at –20°, b) ‒20°, 1-hexene added, c) 5°C, d) 25°C .13 P{1H} NMR spectra of meso-et,ph-P4 in acetone-d6 exposed to air .14 P{1H} NMR spectra of meso-et,ph-P4 in acetone-d6 under 90 psi O2. Recorded 1 day after pressurizing with O2 (black line), 14 days (blue line), 35 days (red line) .5 ppm region of the 1H NMR spectra: sample taken from the reaction with of trans--methylstyrene and meso-(et,ph-P4) in acetone-d6/D2O exposed to air after 2 hours .16 P{1H} NMR spectra of the sample from the reaction with 1-hexene, meso-et,ph-P4 in acetone-d6/D2O under N2 recorded after 24 hrs (blue line), after 3 days (orange line), recorded 1.5 hours upon exposure to air (black line) .5 ppm region of the 1H NMR spectra: sample from reaction with 1-hexene, meso-(et,ph-P4) in acetone-d6/ D2O under N2, 24 hours (blue spectrum), same as above recorded 1.5 hours after exposure to O2(red spectrum).18 P{1H} NMR spectra of the sample from the reaction with 1-hexene, meso-et,ph-P4 in acetone-d6/D2O at 45°C exposed to O2 after 1.1 Binucleating tetraphosphine ligands rac- and meso-et,ph-P4 .2 New stronger binucleating tetraphosphine ligands rac- and meso-et,ph-P4-Ph.3 New P4-Ph ligand type with para substituted internal phenyl rings .1 P{1H} spectrum in CDCl3 of the final product mixture from the reaction of 2 and C2Cl6 in Et2O .2 P{1H} spectrum in CD2Cl2 of the final product mixture from the reaction with 1 eq H(Ph)PCH2P(Ph)H and 1.5 eq of C2Cl6 in Et2O .3 (Bottom spectrum) 31P{1H} NMR spectrum of the crude reaction mixture with 1 and C2Cl6 in toluene and (top spectrum) isolated final product in C6D6.5 P {1H} NMR of the final product mixture in C6D6 obtained after work up from the reaction of o-diiodobenzene with iPrMgBr, followed by addition of PEt2Cl .6 P {1H} NMR spectrum of the crude product mixture obtained from reaction of 3(I) with iPrMgBr, followed by addition of 2 .7 P {1H} NMR spectrum of the final product mixture in C6D6 purified via column chromatography on neutral alumina .8 H NMR spectra of 2.5 ppm region of the meso-et,ph-P4-Ph and unidentified phosphine impurities (red spectrum), mixture of ix meso and rac-et,ph-P4-Ph (black spectrum), and rac-et,ph-P4-Ph (orange spectrum) .9 P {1H} NMR spectra of first set of fractions containing unreacted 3(I) and other phosphine impurities (blue spectrum), second set containing meso-et,ph-P4-Ph and unidentified phosphine impurities (red spectrum), third set mixture of meso and rac-et,ph-P4-Ph (black spectrum), and forth set rac-et,ph-P4-Ph (orange spectrum).10 P {1H} NMR recorded on the sample taken from reaction with 3(I) andiPrMgBr (bottom) after 6h at 0°C and (top) after 24h .11 Final product mixture after 24 hours Mg-I exchange at 0°C in C6D6 .12 P {1H} NMR of the crude sample obtained from reaction of 1-bromo-2 iodobenzene with iPrMgBr (bottom) and final product obtained via distillation under reduced pressure (top spectrum) .13 P {1H} NMR spectrum recorded on the sample taken from reaction of 3(Br) with Mg turnings to generate arylphosphine magnesium reagent.14 (Bottom spectrum) 31P {1H} NMR crude product mixture and (top spectrum) final product mixture purified via column chromatography containing meso et,ph-P4-Ph in 96% purity .15 (Black spectrum) 31P {1H} NMR of 1:1 mixture of rac and meso-et,ph-P4-Ph, (purple spectrum) meso-et,ph-P4-Ph, and (red spectrum) rac-et,ph-P4-Ph .16 (Purple spectrum) 1H NMR of meso-et,ph-P4-Ph, (red spectrum) rac- et,ph-P4-Ph .17 The 31P{1H} NMR of the reaction of PtCl2(cod) and rac-et,ph-P4-Ph inCDCl3 after 2 hours .18 P{1H} NMR of the crude reaction mixture of PtCl2(cod) and rac-et,ph- P4-Ph after 6 hrs of reaction (bottom spectrum) and purified Pt2Cl2(rac-et,ph-P4-Ph), 5R in CDCl3 (top spectrum) .19 ORTEP (50% ellipsoids) of one molecule of Pt2Cl4(rac-et,ph-P4-Ph), 5R, in the asymmetric unit. Hydrogen atoms are omitted for clarity .21 H NMR of methylene bridge region for rac-NiPtCl4(et, ph-P4-Ph) in CDCl3 .22 H NMR of methylene bridge region for rac-Ni2Cl4 (et,ph-P4-Ph) in CD2Cl2 .23 The 31P{1H} NMR of orange powder in C6D6 obtained upon concentration of the filtrate in vacuo. Signals due to 6R are colored in red.
Hydrogen atoms omitted for clarity .25 The 31P{1H} NMR of [rac-Rh2(nbd)2(et,ph-P4-Ph)](BF4)2 in CD2Cl2 .26 The 1H NMR of [rac-Rh2(nbd)2(et,ph-P4-Ph)](BF4)2 in CD2Cl2 .1 P {1H} NMR (experimental and simulated) rac and meso-et,ph-P4- Ph .2 P {1H} NMR (experimental and simulated) meso-et,ph-P4-Ph .3 P {1H} NMR (experimental and simulated) rac-et,ph-P4-Ph .4 H NMR of rac and meso-et,ph-P4-Ph .5 H NMR of meso-et,ph-P4-Ph in C6D6 showing 7.6 H NMR of rac-et,ph-P4-Ph in C6D6 showing 7.7 The 1H NMR of rac-Pt2Cl2(et,ph-P4-Ph), 5R in CD2Cl2.