Degree Name

Master of Science (MS)

Semester of Degree Completion

2001

Thesis Director

Richard L. Keiter

Abstract

Four phosphines (Ph2P)2C=CHPPh2, (p-tol)2PCH2P(p-tol)2, (o-tol)2PCH2P(o-tol)2, Ph2PCH2P(p-tol)2 and their pentacarbonyltungsten complexes have been prepared and studied as part of a continuous investigation of polydentate phosphines that are coordinated as monodentate ligands. The ligand, (Ph2P)2C=CHPPh2, was prepared by base-catalyzed addition of Ph2PH to Ph2PC=CPPh2. Reaction of this ligand with (OC)5WNH2Ph led to formation of a monodentate complex in which the diphenylphosphino group attached to CH=C is coordinated to tungsten, (OC)5W[η1-PPh2CH=C(PPh2)2]. Similar reactions led to the formation of (OC)5W[η1-P(p-tol)2CH2P(p-tol)2] and (OC)5W[η1-P(o-tol)2CH2P(o-tol)2]. The linkage isomers, (OC)5W[η1-PPh2CH2P(p-tol)2] (A) and (OC)5W[η1-P(p-tol)2CH2PPPh2] (B) were also studied and their rates of isomerization in chloroform were followed with 31P{1H} NMR spectroscopy. Rate constants for the conversion of A to B and B to A are (1.4 ± 0.6) x 10-6 s-1 and (6.9 ± 0.3) x 10-7 s-1 at 55°C, respectively. The equilibrium constant, B/A, is 2.00.

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