POLYATOMIC (ZINTL) ANIONS

Another field of synthetic/structural main-group inorganic chemistry where we have made significant contributions is to the study of anions of the heavy main-group elements. These species are synthesized in basic solvent media such as liquid NH₃ or ethylenediamine. Classical chain, ring and cage anions and electron deficient cluster anions are represented. Although single crystal X-ray diffraction is extensively employed for structural characterization, the structures that are determined often times are not representative of all of the species that are present in these solutions. We have therefore promoted the value of multi-NMR spectroscopy as a means to provide a complete picture of the complex equilibria that are characteristic of these systems. As a result, rational explanations are emerging for the interrelationship of structures and synthetic conditions. The multi-NMR studies of these heavy-element systems have also contributed in a significant way to our understanding of the role that relativistic effects play in heavy element nuclear (indirect) spin-spin couplings.

Naked Main-Group Metal Cluster Anions

nido-Pb₉^4- (C_4v)

closo-Pb₉^3- (C_2v)

closo-Ge₅^2- (D_3h)

Coordination of Organometallic Fragments to Naked Main-Group Metal Clusters

closo-Sn₉M(CO)₃^4- (M = Cr, Mo, W)

closo-Pb₉Mo(CO)₃^4-

Classically Bonded Anions

Our studies have led to an understanding of how self-assemblies among main-group chalcogenide anions take place. The recognition that some long-known, simple anions are at the origin of these condensation processes and the conditions that control their formation has provided more rational avenues to the syntheses of anions exhibiting novel structural features and bonding.

Sn₂Ch₆^4- (D_2h)
SnCh₃^2- (D_3h) Sn₂Ch₇^4- (C_s) (Ch = Se and Te)
Sn₄Ch₁₀^4- (T_d)

TlSe₃^3- (D_3h) & Tl₂Se₂^2- (C_2v, butterfly shape)
Tl₄Se₅^4- (C_3v)
Tl₄Se₆^4- (C_2v)
Tl₅Se₅^3- (C_s)

Tl₂Se₆^6- (D_2h)
TlSe₃^3- / Se^2- Tl₃Se₆^3- (C_2v)
Tl₃Se₇^5- (C_3v)
Tl₄Se₈^4- (D_2h chain)
[Tl₂Se₄^2-] (infinite chain).