# Is the term “heteroatom” reserved for exclusive elements?

From my experience, typically in organic chemistry, the implication of "hetero-atom" in some molecule is understood as B, N, O, S, P or a halogen -- or any nonmetallic element, perhaps.

If one describes a nanostructure that contains inorganic and organic ligands (like metal-organic frameworks), is it safe to describe the metals as heteroatoms? Or should the term be reserved for covalent-type atoms only?

For example, is this an acceptable statement?

Snurr and co-workers showed results for simulated H$_2$ sorption in a variety of rht-MOFs containing only carbon and hydrogen in the linkers, as originally these MOFs did not contain heteroatoms other than oxygen and the metal.

• I would argue that this is propably a matter of style much more than one of definition or scientific accuracy. An organic scientist may have other views on that than somebody occupied with inorganics. Take heavy atoms for example, which for some people start with nitrogen, other would start somewhere around silicon/phosphorus, while somebody who works a lot with different metal might at the split only at iron. – tillyboy May 19 '17 at 19:22

The IUPAC Goldbook provides no 'official' definition of the term heteroatom,and as such you're somewhat free to use (and abuse) the term as you see fit.

Since no IUPAC definition exists, it may be helpful for you to define what you plan on calling a heteroatom at the beginning of whatever you're writing, to inform the reader (common practice in scientific literature for poorly defined terms). Clearly an organic chemist would have a very different definition to someone involved in purely metallic synthesis.

I would however, point to several other IUPAC documents in which, whilst no 'definition' of a heteroatom is given, they do suggest lists of possible heteroatoms. For example, the following statement from the IUPAC nomenclature guidelines which includes many elements (including metallic ones, possibly going against your suggested definition). This priority order of heteroatoms is repeated multiple times.

P-22.2.2.1.3 If two or more kinds of heteroatoms occur in the same name, their order of citation follows the sequence: F, Cl, Br, I, O, S, Se, Te, N, P, As, Sb, Bi, Si, Ge, Sn, Pb, B, Al, Ga, In, Tl, Hg.

The most common context is as you've indicated; a heteroatom is typically a non-metallic atom that replaces a part of the hydrocarbon backbone of an organic molecule. However this is not the only context, and a metal atom would also be considered a heteroatom, and the statement that you've made would be acceptable.

Also, here is an example of a somewhat different context from this Wikipedia article:

In the context of zeolites, the term heteroatom refers to partial isomorphous substitution of the typical framework atoms (silicon, aluminium, and phosphorus) by other elements such as beryllium, vanadium, and chromium.