Redox and non-redox reactions of multiply-bonded dirhenium complexes with terminal alkynes and halogens

David Alan Kort, Purdue University

Abstract

The complexes $\rm Re\sb2(\mu$-X)($\mu$-CO)X$\sb3(\mu$-dppm)$\sb2$(CO) (X = Cl or Br) react with terminal alkynes in the presence of TlO$\sb3$SCF$\sb3$ and concentrated HCl to afford the dirhenium alkylidyne complexes $\rm\lbrack Re\sb2(\mu$-X)($\mu$-CO)X$\rm\sb3({\equiv}CCH\sb2R)(L) (\mu$-dppm)$\rm\sb2\rbrack O\sb3SCF\sb3$ (X = Cl or Br; L = CNxylyl or CO; R = n-Pr or n-Bu). These reactions are of higher yield and greater purity than previous synthetic routes to these complexes, developed from the reactions of dirhenium 3-metallafuran complexes. The A-frame monoisocyanide complexes Re$\sb2(\mu$-X)X$\sb3(\mu$-dppm)$\sb2$(CNR) (X = Cl or Br; R = xylyl or t-Bu) react with terminal alkynes in the presence of TlO$\sb3$SCF$\sb3$ to afford the complexes $\rm\lbrack Re\sb2X\sb3(\eta\sp2$-HCCR$\sp\prime)(\mu$-dppm)$\rm\sb2 (CNR)\rbrack O\sb3SCF\sb3$ (X = Cl or Br; R = xylyl or t-Bu; R$\sp\prime$ = H or n-$\rm C\sb3H\sb7)$ in high yield. The physical properties of these compounds were compared and contrasted with the physical properties of the corresponding monocarbonyl/$\eta\sp2$-alkyne complexes. The A-frame monocarbonyl complexes Re$\sb2(\mu$-X)X$\sb3(\mu$-dppm)$\sb2$(CO) (X = Cl or Br) react with Cl$\sb2$ or Br$\sb2$ to afford the oxidative addition products (Re$\sb2(\mu$-Cl)$\rm\sb2Cl\sb3(\mu$-dppm)$\sb2$(CO)) Cl and $\rm\lbrack Re\sb2(\mu$-Br)$\rm\sb2Br\sb3(\mu$-dppm)$\sb2$(CO)) Br$\sb3.$ These complexes react with inorganic reagents as net two-electron oxidants and halide donors. These complexes represent the first examples of fully reversible oxidative addition chemistry to be developed using the electron-rich Re-Re triple bond. The reactions of the A-frame monoisocyanide complexes Re$\sb2(\mu$-X)X$\sb3(\mu$-dppm)$\sb2$(CNR) (X = Cl or Br; R = xylyl or t-Bu) with chlorine (Cl$\sb2)$ afford the oxidative addition products (Re$\sb2(\mu$-Cl)$\rm\sb2Cl\sb3(\mu$-dppm)$\sb2$(CNR)) Cl (R = xylyl or t-Bu). These compounds react with $\rm Re\sb2Cl\sb4(\mu$-dppm)$\sb2$ as net one-electron oxidants and halide donors, producing $\rm Re\sb2Cl\sb5(\mu$-dppm)$\sb2$ and Re$\sb2(\mu$-Cl)$\rm\sb2Cl\sb3(\mu$-dppm)$\sb2$(CNR).

Degree

Ph.D.

Advisors

Walton, Purdue University.

Subject Area

Chemistry

COinS