Question
These rules have 4n, 5n, and 6n versions, depending on whether there are approximately 4, 5, or 6 electrons per vertex, which respectively predict structures based on deltahedra, 3-connected polyhedra, and rings. For 10 points each:
[10h] Name these rules for classifying the structures of clusters, which in the 4n case may be classified as closo, nido, or arachno. These rules are commonly used for clusters of boron and hydrogen, known as boranes.
ANSWER: Wade’s rules [or Wade–Mingos rules; or polyhedral skeletal electron pair theory; or PSEPT]
[10m] Wade’s rules are the molecular orbital theory-based improvement to the earlier analysis of boranes based on B-B-B and B-H-B instances of these bonds. Two of these bonds form the B-H-B bridges in diborane.
ANSWER: three-center two-electron bonds [or 3c-2e bonds]
[10e] Each of the B-H bonds in diborane’s B-H-B bridges has a value of 0.5 for this quantity because a single electron pair is spread over two such bonds. This quantity is 1 for a single bond and 2 for a double bond.
ANSWER: bond order
<Gerhardt Hinkle, Chemistry>
Summary
| 2023 Penn Bowl @ Waterloo | 10/28/2023 | Y | 4 | 22.50 | 100% | 25% | 100% |
| 2023 Penn Bowl @ FSU | 10/28/2023 | Y | 2 | 10.00 | 50% | 0% | 50% |
| 2023 Penn Bowl (Harvard) | 10/21/2023 | Y | 3 | 13.33 | 67% | 33% | 33% |
| 2023 Penn Bowl (Mainsite) | 10/21/2023 | Y | 6 | 11.67 | 67% | 17% | 33% |
| 2023 Penn Bowl (Norcal) | 10/28/2023 | Y | 1 | 20.00 | 100% | 0% | 100% |
| 2023 Penn Bowl (South Central) | 10/28/2023 | Y | 3 | 3.33 | 33% | 0% | 0% |
| 2023 Penn Bowl (UK) | 10/28/2023 | Y | 5 | 14.00 | 60% | 40% | 40% |
Data
| Berkeley C | Stanford | 10 | 0 | 10 | 20 |