I've been promising a post about my own research for the past couple of weeks, so here you are! This post is about the research I did for my Part II project as a fourth year undergraduate back in 2008/09. (Fourth year Chemistry undergrads at Oxford spend the year working in one of the research labs. Which is awesome and should be implemented everywhere.) Anyway if you read my previous rather epic post you'll know that the reactivity of group 6 (Cr, Mo, W) and group 10 (Ni, Pd, Pt) transition metal compounds towards group 15 Zintl ions has been very well studied by Bryan Eichhorn, however very few other transition or post-transition metal compounds have been investigated. So I set out to fill in some of these gaps, and I started by looking beyond group 10 to groups 11 (Cu), 12 (Zn, Cd) and 13 (In). And this is what I found...
Both K3P7
and K3As7 react with Cu5(mes)5 in ethylenediamine and in the presence of 2,2,2-crypt to form [K(2,2,2-crypt)]4[Cu2(E7)2] (E = P, As). These compounds contain the novel cluster anions [Cu2(P7)2]4–
and [Cu2(As7)2]4–. The crystal structure of [Cu2(As7)2]4–shows two As73– cages bridged by a Cu22+ dimetallic centre. Each Cu atom is bound by one As73– cage in an η4-fashion and by the other in an η1-fashion. The two Cu atoms are also linked by a Cu-Cu bond, giving each Cu atom a coordination number of six.
 |
[Cu2(As7)2]4–.
|
K3P7
and K3As7 also react with the group 12 organometallics MPh2 (M = Zn, Cd) and 2,2,2-crypt to form [K(2,2,2-crypt)]4[M(E7)2]
(M = Zn: E = P, As; M = Cd: E = P). These contain the novel cluster anions [Zn(P7)2]4–, [Zn(As7)2]4– and [Cd(P7)2]4–. The crystal structures of [Zn(P7)2]4–
and [Cd(P7)2]4– both show two P73– clusters bridged by a metal atom. Both P73– cages are bound in an η2-fashion to the metal centre, resulting a a distorted tetrahedral coordiantion geometry. Each η2-P7
acts as a four-electron donor, and the metal is formally in the +2 oxidation state with a d10
electron configuration. The metal centre therefore has eighteen valence electrons and is electronically saturated.
 |
[Zn(P7)2]4–.
|
 |
[Cd(P7)2]4–.
|
Moving on to group 13, K3P7 and K3As7 react with InPh3, again in ethylenediamine and in the presence of 2,2,2-crypt to form the compounds [K(2,2,2-crypt)]2[E7InPh2]
(E = P, As), which contain the In-functionalised cluster anions [P7InPh2]2– and [As7InPh2]2–. The crystal structure of [P7InPh2]2–
shows a P73– cage bound in an η2-fashion to a four-electron (fourteen if the d electrons are taken into account) [InPh2]+
fragment, resulting in a distorted tetrahedral coordination geometry. The η2-P7
acts as a four-electron donor, so that overall the In centre has eight (eighteen) valence electrons and is electronically saturated.
 |
[P7InPh2]2–.
|
So that's what I spent a year doing. Pretty cool, huh? If you want to know more about any of these compounds, why not read the paper? A second post about my research should be coming soon.
No comments:
Post a Comment