Isolation and X‑ray Structure of a Dialkylbismuth(III) Iodo “Nanosquare”: Breaking the Polymeric Mold of R2BiX

• Published in: Inorganic chemistry 2019-10, Vol.58 (20), p.13751-13754
• Main Authors: Cashman, Brenna K, Sandmann, Karissa M, Rose, Michael J
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.9b01969

We report the synthesis, X-ray structure, and solution behavior of a “nanosquare” formed by four repeating ( i Pr2BiI) units. The title complex [ i Pr2BiI]4 (1) formed spontaneously as the major product from the reaction of i Pr3Bi with MI2 (M = Mn, Co, Fe). Complex 1 was then more directly synthesized via bromination of i Pr3Bi to form ( i Pr2BiBr), followed by iodide substitution. The X-ray structure of 1 exhibited acute Bi–I–Bi bonds (∼85–95°) that enabled formation of the hollow square motif. Synthetic control experiments with R2BiX (R = i Pr, Bn; X = I, Br) revealed that the identities of both the halide and bismuth R group are determinants for square formation: the bromo-substituted [ i Pr2BiBr] n (2) and benzyl-substituted [Bn2BiI] n (3) variants formed only polymers as determined by X-ray crystallography. Density functional theory calculations revealed nearly pure p-orbital-based bonding molecular orbitals on both iodide and bismuth, facilitating the ∼90°/180° bonding motifs.