Topics (384k) Articles (398k) Users (410) Discussions (242) Comments (383) Files (13k) New article
A pi-donor ligand has an occupied orbital that can overlap sideways with a metal orbital. In the standard octahedral splitting picture it raises the metal -derived levels, tending to reduce their separation from .
A pi-acceptor ligand has a suitable unoccupied orbital for pi backbonding. Stabilization of metal -derived levels increases the usual octahedral splitting.
A nitro ligand is N-bound nitrite, , normally treated as a sigma-donor ligand and pi-acceptor ligand. The word here concerns coordinated nitrite, not an independently introduced organic nitro substituent.
A nitrito ligand is O-bound nitrite, . Its oxygen donor provides sigma donation and can provide pi donation; an N-bound nitro ligand is its linkage isomer.
A hydroxo ligand is coordinated . Deprotonation of coordinated water can make it without first breaking the metal–oxygen bond.
A phosphine ligand such as donates a phosphorus lone pair. It can also accept pi backbonding into orbitals with substantial P–R antibonding character; phosphorus orbitals need not be essential acceptors. Alkyl substitution generally increases sigma donation relative to electron-withdrawing substituents.
A carbonyl ligand is coordinated carbon monoxide, usually attached through carbon. Sigma donation and pi backbonding cooperate in the metal–carbon bond. Terminal and bridging forms have different electron-counting descriptions.
A chloride ligand is coordinated . It is an anionic two-electron donor in ionic electron counting, with occupied orbitals that can contribute pi donation.
An amido ligand contains an anionic nitrogen donor, such as . A neutral secondary amine retaining its N–H bond is a different donor type; confusing them changes formal metal oxidation state.
The cyclopentadienyl ligand is based on . In its common mode it binds through five ring carbons and donates six electrons in ionic electron counting. Ring substitution can create distinct NMR environments.
An allyl ligand can bind as , donating four electrons in ionic electron counting. Protonation can release an alkene and make coordination sites available.
A phosphite ligand such as binds through a phosphorus lone pair and can accept pi backbonding. Its donation and acceptance differ from those of both phosphine ligands and carbonyl ligands.
An alkene ligand commonly binds through both double-bond carbons, . The balance of donation and backbonding is described by the Dewar-Chatt-Duncanson model.
A bromide ligand is coordinated , conventionally an anionic two-electron donor in ionic electron counting.
An alkyne bound through its pi system. The neutral two-electron donor picture and a reduced metallacyclic picture emphasize different limits of the same bonding interaction.
Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 2. You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website.
Figure 3. Visual Studio Code extension installation.
Figure 5. . You can also edit articles on the Web editor without installing anything locally. Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension. 
- Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact