Zintl ions are naked anionic clusters of main group elements (e.g. Sn94- and Sb73-) that have been known for over 100 years.  Bimetallic Zintl ions provide an excellent bridge between large molecular clusters and small metallic nanoparticles.  Three examples are shown in Figure 1.   

These complexes show remarkable dynamic properties and are ideally suited for NMR studies. These clusters and their transition metal derivatives show a wide range of dynamic behavior; including rapid global exchange of up to 18 metal atoms in the Pd2@Sn184- ion.  The compounds span large regions spectral regions of the chemical shift windows (119Sn = 4388 ppm, 207Pb = 5965 ppm) and show a variety of couplings to various heteroatoms (e.g. 1H, 31P, 195Pt). In addition, 117Sn satellites on 119Sn NMR resonances are used to assess fluxionality and nuclearity in the tin-containing derivates.

Several of these clusters posses high symmetry structures, such as the perfect Ih point symmetry in the Pt@Pb122-  and As@Ni12@As203- clusters that are icosahedra or have icosahedral subunits (Figure 2).  The As20 shell of As@Ni12@As203- is isosturctural to Ti8C12 and C20, but unlike the metcars and small fullerenes, they can also be prepared in macroscopic quantities, fully characterized and used in subsequent reactions. 

In addition to being ideal models for small bimetallic nanoparticles, they are excellent precursors to phase-specific bimetallic NPs.  For example, we can prepare 2 – 10 nm NPs all of the Ni-As phases in the phase diagram by controlling stoichiometry and conditions in reactions between Ni(COD)2 and As73-.  XRD and HR-TEM analyses (Figure 3) show the uniform, single-phase syntheses.

Representative Publications

  1. F.Sanem Kocak, Domonique O. Downing, Peter Zavalij, Y.-F. Lam, Andrei N. Vedernikov and Bryan Eichhorn “The

Surprising Acid-Base and Ion-Sequestration Chemistry of Sn94-: HSn93-, Ni@HSn93- and the Sn93- ion revisited”

J. Am. Chem. Soc., 2012, 134, 9733-9740.

Andrej Grubisic, Haopeng Wang, Xiang Li, Yeon-Jae Ko, F. Sanem Kocak, Mark Pederson, Kit Bowen, Bryan Eichhorn,

“Photoemission Studies and Electronic Properties of the Pt@Pb101-/2- and Pt@Pb121-/2- Anions” Proc. Nat. Acad. Sci., 

2011, 108, 14757–14762.

  1. F.Sanem Kocak, Peter Zavalij, and Bryan W. Eichhorn “Reactions of exo-substituted RSn93- Clusters with Pd:

Endohedral Formation and Oxidative Insertions ” Chem.-Eur. J., 2011, 17, 4858-4863.

Bryan Eichhorn and Sanem Kocak “Dynamic Properties of the Group 14 Zintl Ions and Their Derivatives” 2011, Structure and Bonding, 140, 59-89.

Sanem Kocak, Peter Zavalij, and Bryan W. Eichhorn “Reactions of exo-substituted RSn93- Clusters with Pd: Endohedral Formation and Oxidative Insertions” Chem.-Eur. J., 2011, 17, 4858-4863.

Domonique O. Downing, Peter Zavalij, Bryan W. Eichhorn “The closo-[Sn9Ir(cod)]3- and [Pb9Ir(cod)]3- Zintl Ions:  Isostructural Ir(I) Derivatives of the nido-E94- Anions (E = Sn, Pb)” Eur. J. Inorg. Chem., 2010, 890–894.

Sanem Kocak, Peter Zavalij, Yiu-Fai Lam and Bryan W. Eichhorn “Substituent-Dependent Exchange Mechanisms in Highly Fluxional RSn93- Anions” Chem. Commun. 2009, 4197–4199.

Sanem Kocak, Peter Zavalij, Yiu-Fai Lam and Bryan W. Eichhorn “Solution Dynamics and Gas Phase Chemistry of Pd2@Sn184-” Inorg. Chem., 2008, 47, 3515-3520.

Banu Kesanli, Jordan Halsig, Yiu-Fai Lam, Peter Zavalij, James Fettinger and Bryan Eichhorn “Oxidative Coupling and Cluster Growth in the Highly Fluxional Platinum Derivatives of Sn94-: Synthesis, Characterization and Solution Dynamics of Pt2@Sn174- and Pt@Sn9H3-” J. Am. Chem. Soc., 2007, 129, 4567.

E. N. Esenturk, J. Fettinger, Y.-F. Lam and B. Eichhorn “Pt@Pb122-” Angew. Chem. Int. Ed., 2004, 43, 2132-2134.

M. Moses, J. Fettinger and B. Eichhorn “Interpenetrating As20 Fullerene and Ni12 Icosahedra in the Onion-Skin [As@Ni12@As20]3- Ion” Science, 2003, 300, 778.


Zintl Clusters –

the Interface Between

Large Clusters and Nanoparticles