Chemists string together four different group 15 elements in a single molecule

One of the joys of inorganic chemistry is exploring the periodic table to see what new and interesting things can be done with the elements. For Alexander Hinz of Oxford University and Axel Schulz and Alexander Villinger of the University of Rostock, that joy comes from stringing together as many different elements in a periodic group as possible to form heterocyclic rings.

The team was working toward making a ring containing four different pnictogens (group 15 elements, N to Bi), but they were unable to close the linear precursor. So the researchers have settled for now on reporting the acyclic compound, which includes an unprecedented, Sb-N-As=P chain (Chem. Eur. J. 2016, DOI: 10.1002/chem.201601916).

“To the best of our knowledge, our compound is the first acyclic molecular species featuring four different pnictogens in a chain,” Schulz tells C&EN. “In principle, it should also be possible to include bismuth, but that would be much more difficult.”

On the periodic table, only groups 13 to 15 are likely to pull off the complete feat. So far, there are no examples from group 13 (B to Tl) with four or more elements. And although there are a few molecules containing various combinations of four group 14 elements (C to Pb), there is no species with all five.

“This paper shows the elegance of synthesis in main-group chemistry,” says Manfred Scheer of the University of Regensburg. “It’s impressive that by using one-element building blocks one succeeds in the alignment of four different adjacent pnictogens in one compound.”