Transition Metal Complexes of a Novel Tetradentate Phosphine and of a New Diphosphine Ether Mark R

Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1991 Transition metal complexes of a novel tetradentate phosphine and of a new diphosphine ether Mark R. Mason Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Inorganic Chemistry Commons Recommended Citation Mason, Mark R., "Transition metal complexes of a novel tetradentate phosphine and of a new diphosphine ether " (1991). Retrospective Theses and Dissertations. 9554. https://lib.dr.iastate.edu/rtd/9554 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. 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Mason A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Depaitment: Chemistry Major Inorganic Chemistry Approved: Signature was redacted for privacy. r Work Signature was redacted for privacy. Signature was redacted for privacy. Iowa State University Ames, Iowa 1991 ii TABLE OF CONTENTS Eâgs V DEDICATION PREFACE 1 SECTION L GENERAL INTRODUCTION 2 INTRODUCTION 3 MULTTTERTIARY PHOSPHINES 7 PHOSPHINE ETHERS 22 STATEMENT OF RESEARCH PROJECT 35 REFERENCES 39 SECTION n. COORDINATION CHEMISTRY OF A NEW 48 TETRATERTIARY PHOSPHINE LIGAND ABSTRACT 49 INTRODUCTION 51 EXPERIMENTAL SECTION 54 RESULTS AND DISCUSSION 73 ACKNOWLEDGMENTS 105 REFERENCES 106 SUPPLEMENTARY MATERIAL 112 SECTION m. BIDENTATE AND TRIDENTATE COORDINATION 130 MODES OF A NOVEL BICYCLIC DITERTIARY PHOSPHINE ETHER ABSTRACT 131 INTRODUCTION 132 iii EXPERIMENTAL SECTION 135 RESULTS AND DISCUSSION 151 ACKNOWLEDGMENTS 173 REFERENCES 174 SUPPLEMENTARY MATERIAL 178 SECTION IV. UNAMBIGUOUS DEMONSTRATCON OF 211 VACANT SITE INVERSIONiN A e/5-P2M(CO)3 INTERMEDIATE ABSTRACT 212 COMMUNICATION 213 ACKNOWLEDGMENTS 218 REFERENCES 219 SECTION V, LIGAND SUBSTITUTION REACTIONS IN 221 GROUP VI METAL CARBONYL COMPLEXES OF A NOVEL BICYCUC DITERTIARY PHOSPHINE ETHER ABSTRACT 222 INTRODUCTION 223 EXPERIMENTAL SECTION 226 RESULTS AND DISCUSSION 237 ACKNOWLEDGMENTS 254 REFERENCES 255 SECTION VI. FLUORIDE-ASSISTED REDUCTION OF 259 PALLADIUM# PHOSPHINE COMPLEXES ABSTRACT 260 iv COMMUNICATION 261 ACKNOWLEDGMENTS 264 REFERENCES 265 SECTION vn. A NEW REDOX REACTION INVOLVING 267 FLUORIDE AND PHOSPHINE COMPLEXES OF GROUP X METALS. CRYSTAL AND MOLECULAR STRUCTURE OF Pd(dppp)2. ABSTRACT 268 INTRODUCTION 269 EXPERIMENTAL SECTION 271 RESULTS AND DISCUSSION 286 ACKNOWLEDGMENTS 302 REFERENCES 303 SUPPLEMENTARY MATERIAL 308 GENERAL SUMMARY 325 ACKNOWLEDGMENTS 327 V DEDICATION To my wife and family for their constant love and encouragement 1 PREFACE This dissertation consists of seven sections. The first section is a review of the pertinent literature on which this thesis is based. At the end of the first section is a Statement of Research Project which outlines the goals of the research described herein. Each of the remaining six sections represents research as it was submitted for journal publication- Literature citations, tables, and figures pertain only to the section in which they are included. Section n involved the reinvestigation and continuation of a project initiated by Dr. Colleen M. Duff, and as such, a brief description of her contribution is included in the Acknowledgments portion of that section. Likewise, all other contributions to the work presented herein are similarly acknowledged. 2 SECTION L GENERAL INTRODUCTION 3 INTRODUCTION Phosphines have constituted one of the most extensively investigated classes of ligands in transition metal chemistry. Their use in a variety of homogeneous transition metal catalyzed applications of industrial significance, such as hydroformylation, hydrogénation, olefin isomerization, olefin oligomerization and olefin hydrocyanation (a phosphite is used in the Du Pont adiponitrile process), attest to their importance in the field of organometallic chemistry. ^ Multidentate phosphines, in particular, have several distinct advantages which account for their increasing use. Careful adjustments to steric, electronic, and structural features in multidentate phosphines can be used to control the coordination number, stereochemistry, and basicity at a metal center. In comparison to their monodentate counterparts, chelation of multidentate phosphines has been found to add increased stability to transition metal complexes. The chelate ring size is also of great importance and may drastically alter the reactivity of a given complex. For example, the bidentate ligand dppm prefers to bridge two metal centers rather than chelate to one metal. Hence "A-fiame" bimetallic conçlexes comprise a large portion of the chemistry of this ligand. As a second example, the rates of rhodium-catalyzed hydrogénation and hydroformylation have also been shown to be highly dependent on chelate ring size.^ Multidentate phosphines may also possess other donor atoms including N, As, Sb, O, S, and Se. Incorporation of these donor atoms into phosphine ligands has been achieved using a variety of functional groups such as amines,^ thioetherSj^®»^ ethers, esters,^ phosphine oxides, phosphine sulfides,^» ^ and phosphine selenides.^ Mixed donor ligands which contain phosphine groups, as well as weak donor atoms such as N, O, S, or Se, have been labeled "hemilabile".^ The phosphine groups provide a strong 4 anchor to the metal complex but the weak donors are readily displaced by other substrates, thus providing accessible coordination sites on the metal. Coordinative unsaturation is a known prerequisite for a catalytic transition metal catalyzed system.^ Numerous review articles pertaining to phosphrne transition metal complexes have appeared in the literature over the past twenty years. Early reviews by McAuliffe detailed the chemistry of bidentate and tetradentate phosphines including some mixed donor ligands.^ Meek published^O a less extensive review of phosphine transition metal chemistiy in 1978. A legendary review addressing steric factors in phosphine complexes was published^ ^ by Tolman in 1977. The coverage in this review included cone angles, chelate ring effects, NMR spectroscopy and some X-ray crystallographic data. Garrou has presented two reviews recentiy; the first detailing P-C bond cleavage in homogeneous systems^^ and the second discussing the utility of ^^P NMR spectroscopy in the study of transition metal phosphine complexes.^^ An extensive compilation of relevant ^Ip NMR spectroscopic data and references has also been included in a recent text edited by Quin and Verkade.^^ An excellent review of transition metal catalyzed asymmetric synthesis, including a discussion of approximately thirty chiral bidentate phosphines, has also been published. The most recent review was put forth by McAuliffe in 1987.^^ Included in his discussion are common synthetic routes used in the preparation of phosphines as well as recent advances in the chemistry of macrocyclic phosphine ligands. Although the number of review articles relevant to this topic is large (above is only a partial listing), several recent developments in the area of multidentate phosphines have not been covered. Additionally, the topic of mixed donor ligands has received littie attention in review articles and the author is aware of no review articles concerning phosphine ether ligands. This general survey will thus be divided into two parts. The 5 - - first will cover tertiary phosphines with a denticity of three or greater, concentrating

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