Degree Type

Dissertation

Date of Award

1991

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

John G. Verkade

Abstract

This dissertation describes the synthesis and coordination chemistry of two new phosphine ligands and a novel fluoride-induced redox reaction. The tetratertiary phosphine 2,3-bis(diphenylphosphinomethyl)-1,4-bis(diphenylphosphino)butane (1) coordinates to a variety of transition metal fragments (ML[subscript] n) to yield bimetallic complexes of the type L[subscript] nM(PPh[subscript]2CH[subscript]2)[subscript]2CHCH(CH[subscript]2Ph[subscript]2P)[subscript]2ML[subscript] n, and monometallic complexes of Mo(CO)[subscript]3 wherein 1 coordinates in a tridentate fashion. The structures of the homobimetallic complexes where ML[subscript] n = NiCl[subscript]2, PdCl[subscript]2, and PdI[subscript]2 have been confirmed by X-ray crystallography. Reaction of (Cl[subscript]2Pd(Ph[subscript]2PCH[subscript]2)[subscript]2CH) [subscript]2 with 1 in air gives Cl[subscript]2Pd(PPh[subscript]2Ch[subscript]2)[subscript]2CHCH(CH[subscript]2P(O)Ph[subscript]2)[subscript]2 via metal-catalyzed air oxidation. The structure of this complex is also reported. Unsuccessful attempts to prepare monometallic complexes of Rh(I), Ni(II), and Pd(II) wherein 1 would coordinate as a tetradentate ligand are also examined;The new ditertiary phosphine ether cis-1,5-bis(diphenylphosphinomethyl)-3-oxabicyclo(3.3.0) octane (2) coordinates to transition metals in either a bidentate (P, P[superscript]') manner through the two phosphorus donors, or in a tridentate (P,P[superscript]',O) manner in which the ether oxygen is also coordinated. Single-crystal X-ray diffraction studies on (2-P,P[superscript]')Mo(CO)[subscript]4 and fac-(2-P,P[superscript]',O)W(CO)[subscript]3 verify the bidentate and tridentate coordination modes of 2, respectively. The metal-ether interaction in the complexes fac-(2-P,P[superscript]',O)M(CO)[subscript]3 are liable to stereospecific substitution by additional ligands (L) to yield two diastereomers of fac-(2-P,P[superscript]')M(L)(CO)[subscript]3 (M = Mo, W; L = CO, [superscript]13CO, (P(OCH[subscript]2)[subscript]3CCH[subscript]3), CH[subscript]3CN, py, pip) in each case. Complexes of the N-donor ligands equilibrate in solution with (2-P,P[superscript]',O)M(CO)[subscript]3 and uncoordinated N-donor ligand. This equilibrium was verified by monitoring the exchange reaction between fac-(2-P,P[superscript]')W(NCCH[subscript]3)(CO)[subscript]3 and CD[subscript]3CN by [superscript]2H NMR spectroscopy;In the course of this work, it was discovered that addition of fluoride to palladium(II) phosphine complexes results in a redox reaction yielding a difluorophosphorane and a phosphine complex of palladium(0). This reaction has been explored utilizing PPh[subscript]3, Ph[subscript]2P(CH[subscript]2)[subscript] nPPh[subscript]2(n = 1-4), Ph[subscript]2PCH[subscript]2C(CH[subscript]3)[subscript]2CH[subscript]2PPh[subscript]2, MePh[subscript]2P, and P(CH[subscript]2CH[subscript]2CN)[subscript]3; several solvent systems and temperatures; and both hydrated and anhydrous fluoride sources. The rapid reduction of ((Ph[subscript]3P)[subscript]3PdCl) BF[subscript]4 to yield Pd(PPh[subscript]3)[subscript]2 in the presence of fluoride and its relevance to the previously reported synthesis of (Pd[subscript]3Cl([mu][subscript]2-PPh[subscript]2)[subscript]2(PPh[subscript]3)[subscript]3) BF[subscript]4 is also discussed. Complexes of platinum were also found to undergo this fluoride-induced redox reaction, but Ni complexes yield only NiF[subscript]2.

DOI

https://doi.org/10.31274/rtd-180813-11520

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Mark R. Mason

Language

en

Proquest ID

AAI9126222

File Format

application/pdf

File Size

332 pages

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