Ligand Toolkit

Hey, guys! It’s been forever, hasn’t it? [laughs sadly] I’m back to studying, and this time, I’m putting together a ligand sheet.

I apologize in advanced, because this might not be the most fascinating thing, but I’ll be referencing these a lot in my next posts, and I need to know them anyway, sooo…

(I’m still watching the cat video. ^^)


Ligand Toolkit

Hydrogen Ligands:

Hydrido: H

  • Two-electron donor
  • No pi accepting ability
  • Bonds to soft metals
  • Negatively charged

Carbon Ligands:

Carbonyl: CO

  • Two-electron sigma donor through carbon
  • Pi-accepting into pi antibonding orbitals
  • Bonds to soft metals
  • Neutral charge

Cyanido: CN

  • Two-electron sigma donor through carbon
  • Pi-accepting into pi antibonding orbitals
  • Bonds to hard and soft metals
  • Negatively charged

Alkenes

  • Two-electron sigma donor through pi orbitals
  • Pi-accepting into pi antibonding orbitals
  • Bond to soft and hard metals
  • Neutral charge

Alkynes

  • Two-electron (monodentate) or four-electron (bidentate bridging) sigma donors through pi orbitals
  • Pi-accepting into pi antibonding orbitals
  • Bond to soft and hard metals
  • Neutral charge

Cyclic Aromatic

Benzene: η6-C6H6

  •  Six-electron sigma donor through pi orbitals
  • Pi-accepting into pi antibonding orbitals
  • Bonds to soft metals
  • Neutral charge

Cyclopentadienyl: η5-C5H5

  • Six-electron sigma donor through pi orbitals
  • Pi-accepting into pi antibonding orbitals
  • Bonds to soft and hard metals
  • Negatively charged

Carbene

Carbenes: CRR’

  • Two-electron sigma donor through sp2 on carbon
  • Pi-accepting into 2p orbital on carbon
  • Bond to soft metals
  • Neutral charge

Carbanion

Alkyl and Aryl Carbanions

  • Two-electron sigma donor through sp3 on carbon
  • Possible pi-accepting on aryl carbanions through pi antibonding orbitals
  • Bond to soft and hard metals
  • Negatively charged

Acyl

Acyl: C(O)R

  • Two-electron sigma donor through sp2 on carbon
  • Possible pi-accepting through pi antibonding orbitals
  • Bond to soft metals
  • Negatively charged

Allyl

Allyl: η3-C3H5

  • Four-electron sigma donor through pi orbitals
  • Pi-accepting through pi antibonding orbitals
  • Bonds to soft metals
  • Negatively charged

Nitrogen Ligands:

Aliphatic Amines

  • Two-electron sigma donor through sp3 on nitrogen
  • No pi accepting
  • Bond to hard metals
  • Neutral charge

Heterocyclic Nitrogen Bases (Pyridine, Imidazole, etc.)

  • Two-electron sigma donor through sp2 on nitrogen
  • Possible pi-accepting into pi antibonding orbitals
  • Bonds to soft and hard metals
  • Neutral charge

Imines: C=N

  • Two-electron sigma donor through sp2 on nitrogen
  • Pi-accepting into pi antibonding orbitals
  • Bonds to soft and hard metals
  • Neural charge

Nitrile: R-CN

  • Two-electron sigma donor through sp on nitrogen
  • Possible pi-accepting into pi antibonding orbitals
  • Bonds to soft and hard metals
  • Neural charge

Dinitrogen: N2

  • Two-electron sigma donor through sp on nitrogen
  • Pi-accepting into pi antibonding orbitals
  • Bonds to soft metals
  • Neural charge

Nitrosyl: NO

  • Has two forms: linear (triple bonded) and bent (double bonded)

Linear Nitrosyl:

  • Two-electron sigma donor through sp on nitrogen
  • Pi-accepting into pi antibonding orbitals
  • Bonds to soft metals
  • Positive charge

Bent Nitrosyl:

  • Two-electron sigma donor through sp2 on nitrogen
  • Pi-accepting into pi antibonding orbitals
  • Bonds to soft metals
  • Negative charge

Phosphorus Ligands:

Phosphine, Phosphite

  • Two-electron sigma donor per phosphorus
  • Pi-accepting into d orbitals (in phosphite)
  • Bonds to soft metals
  • Neutral charge

Oxygen Ligands:

Ether, Alcohol, Aqua

  • Two-electron sigma donors
  • No pi backbonding
  • Weaky bond to hard metals
  • Neutral charge

Alkoxo an Aryloxo: RO

  • Two-electron donors
  • No pi backbonding
  • Strongly bond to hard metals
  • Negatively charged

Beta-Diketonato

  • Four-electron donors (chelating)
  • Pi-accepting through pi antibonding orbitals
  • Bond to soft and hard metals
  • Negatively charged

Carboxylato

  • Two-electron donors per carboxylato group
  • No pi-backbonding
  • Bond to hard metals
  • Negatively charged

Sulfur Ligands:

Thiolato

  • Two-electron donors
  • No pi-backbonding
  • Bond to soft metals
  • Negatively charged

Dithiocarbamato

  • Four-electron donor (chelating)
  • No pi-backbonding
  • Negatively charged

Halide Ligands:

Halido

  • Either two-electron donor or four-electron bridging

Macrocyclic Ligands:

Porphyrinato, Crown Ethers, Cryptands

  • Form more stable complexes than equivalent numbers of nonchelating ligands

All right! That’s it! I’m done! Now I’m going to watch the Iron Bowl! (Not that I have a choice… I’m basically watching it right now, so…)

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