The bond bundle in open systems

Much of modern chemistry is concerned with the properties and dynamics of chemical bonds. Although they have been described variously, the most familiar representation is that of a link connecting two atoms. However, no one has yet developed a scheme by which to partition a molecule into bond volumes with well‐defined properties. As a consequence, the chemical bond is left as nothing more than a heuristic devise. Here, we show molecules can be partitioned into bond‐bundles–volumes that share many of the properties associated with the conceptual bond. This partitioning follows naturally through an extension of Baders topological theory of molecular structure. Surprisingly, it also bounds regions of space containing nonbonding or lone‐pair electrons and leads to bond orders consistent with those expected from theories of directed valance. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010