The group 14 Zintl clusters [E\u2089]\u2074\u207B (E = Ge, Sn, Pb) have been reacted with organometallic reagents in solution in the presence of alkali metal cation sequestering agents. The synthesis, characterisation and reactivity studies of the resultant complexes are reported herein.

These negatively charged clusters reductively cleave one of the M\u2013C bonds in the group 12 homoleptic organometallic reagents MR\u2082 (M = Zn, Cd; R = Ph, mes, \u2071Pr) to yield \u03B7\u2074-coordinated functionalised clusters closo-[E\u2089MR]\u00B3\u207B. They can also activate both of the M\u2013C bonds in Cd(mes)\u2082 to form metal-bridged dimers [Ge\u2089CdGe\u2089]\u2076\u207B and [Pb\u2089CdCdPb\u2089]\u2076\u207B. Investigating the reactivity of the functionalised cluster [E\u2089CdPh]\u00B3\u207B (E = Sn, Pb) towards HSn(\u207FBu)\u2083 results in the synthesis of the novel closo-clusters [E\u2089CdSn(\u207FBu)\u2083]\u00B3\u207B.

The reaction of K\u2084Ge\u2089 with the heteroleptic organometallic reagent Fe(COT)(CO)\u2083 yields the metalated cluster anion [Ge\u2088Fe(CO)\u2083]\u00B3\u207B, in which the nuclearity of the Zintl anion is altered upon coordination of the [Fe(CO)\u2083] moiety. Two side products have also been isolated as [K(2,2,2-crypt)]\u207A salts of [Fe(\u03B7\u00B3-C\u2088H\u2088)(CO)\u2083]\u207B and [Fe\u2082(\u03B7\u00B3, \u03B7\u2032\u00B3-C16)(CO)\u2086]\u00B2\u207B.

In the presence of highly reduced Zintl anions, all the M\u2013C bonds in homoleptic mid-row transition metal organometallic reagents can also be cleaved. These \u2018naked\u2019 metal atoms have templated the formation of the endohedral clusters [Fe@Ge₁₀]\u00B3\u207B, [Fe@Sn₁₀]\u00B3\u207B and [Mn@Pb₁₂]\u00B3\u207B. These clusters adopt very different geometries and the electronic origin of their structures has been investigated in-depth by DFT calculations. Structural characterisation of some side products is also reported for: [E\u2089(mes)]\u00B3\u207B (E = Ge, Sn) and [Ge\u2089Mn(mes)]\u00B3\u207B.