Transition Metal Polypnictides from Zintl Ions
Transition Metal Polypnictides from Zintl Ions
Files
Publication or External Link
Date
1995
Authors
Charles, Scott
Advisor
Eichhorn, Bryan W.
Citation
DRUM DOI
Abstract
The chemistry of the soluble E7 3- ions (E = P, As, Sb) with various transition
metal complexes has been investigated. Alloys of K3E7 react with (arene)M(CO)3 (M
= Cr, Mo, W) complexes in the presence of three equivalents of 2,2,2-crypt in
ethylenediamine to give [K(2,2,2-crypt)]3[E7M(CO)3] complexes. Nine
[E7M(CO)3] 3- compounds (E = P, As, Sb; M = Cr, Mo, W) have been prepared. The
compounds have norbomadiene-like E7 fragments, with a formal negative charge
associated with the unique two-coordinate pnictogen furthest from the transition
metal. The bonding is described as E7 π-type interactions with the metal center. 31p
NMR studies show that these compounds undergo an intramolecular wagging process
in solution. The [E7M(C0)3] 3- ions are modestly basic and highly nucleophilic. The
complexes react with weak acids, tetraalkylammonium salts and
(arene)M'(CO)3 complexes to form the [K(2,2,2-crypt)]2[HE7M(CO)3], [K(2,2,2-
crypt)]2[RE7M(CO)3] and [K(2,2,2-crypt)]3[(L2)(CO)3M'E7M(CO)3] compounds,
respectively. Each of the structures contains a norbornadiene-like E7 fragment bound
η4 to the M(CO)3 fragment and η1 to the appended moiety [H+, R+, M(CO)3(en)] that is attached to the pnictogen atom furthest from the M(CO)3 center. The [K(2,2,2-crypt)]3 [η4-E7M(CO)3] complexes also react with carbon monoxide at the M(CO)3 center and reversible binds CO to form [K(2,2,2-crypt)]3[η4-E7M(CO)4] complexes.
These complexes are more easily protonated and undergo faster alkylations of the E7
cages than the parent [K(2,2,2-crypt)]3[η4-E7M(CO)3] compounds. Each of these
structures contains an E7 fragment bound η2 to the M(C0)4 center. Products were
characterized by various physical and spectroscopic techniques including UV-vis, IR,
1H, 13C, and 31P NMR spectroscopies, mass spectrometry, elemental analyses, and
single crystal X-ray diffraction studies.