NacNac explained

NacNac is a class of anionic bidentate ligands. 1,3-Diketimines are often referred to as "HNacNac", a modification of the abbreviation Hacac used for 1,3-diketones. These species can exist as a mixture of tautomers.[1]

Preparation of ligands and complexes

Acetylacetone and related 1,3-diketones condense with primary alkyl- or arylamines resulting in replacement of the carbonyl oxygen atoms with NR groups, where R = aryl, alkyl. To prepare 1,3-diketimines from bulky amines, e.g. 2,4,6-trimethylanilines, prolonged reaction times are required. 2,6-Diisopropylaniline is a common bulky building block.

Deprotonation of HNacNac compounds affords anionic bidentate ligands that form a variety of coordination complexes.[2] Some derivatives with large R groups can be used to stabilize low valent main group and transition metal complexes.[3] Unlike the situation for the acetylacetonates, the steric properties of the coordinating atoms in NacNac ligands is adjustable by changes in the R substituent. Attachment to a metal center is usually carried out by initial deprotonation of HNacNac with n-butyllithium; the lithium derivative is then treated with a metal chloride to eliminate lithium chloride. In some cases, HNacNacs also serve as charge-neutral 1,3-diimine ligands.

Related NacNac ligands

NacNac ligands are diimine analogues of acetylacetonate ligands. An intermediate class of ligands are derived from monoimino-ketones.[4] [5] The first Dipp-NacNac ligand was synthesized by Dr. Francis S. Mair in 1998.[6]

See also

References

  1. D. J.. Mindiola . P. L.. Holland. T. H. . Warren . Complexes of Bulky β-Diketiminate Ligands . . 2010 . 35 . 1–55 . 10.1002/9780470651568.ch1.
  2. Bourget-Merle . L. . Lappert. M. F. . Severn . J. R. . The Chemistry of Diketiminatometal Complexes . . 2002 . 102 . 3031–3066 . 10.1021/cr010424r.
  3. Qian. B.. Ward. D. L.. Smith. M.R. . Synthesis, Structure, and Reactivity of β-Diketiminato Aluminum Complexes . . 1998 . 17 . 3070–3076 . 10.1021/om970886o .
  4. Birgit . Weber . Ernst-G. . Jäger . Structure and Magnetic Properties of Iron(II/III) Complexes with -Coordinating Schiff Base-Like Ligands. Eur. J. Inorg. Chem. . 2009. 455 . 10.1002/ejic.200990003 . 2009.
  5. Dennis P. . Riley . Daryle H. . Busch . Macrocyclic Tetraazatetraenato Ligands and their Metal Complexes . . 1978 . 18 . 36 . 10.1002/9780470132494.ch7.
  6. Mair. Frank S.. Cope. Elaine K.. Clegg. William. Edwards. Andrew J.. Structural Characterization of [(2,6-Pr<sup>i</sup><sub>2</sub>C<sub>6</sub>H<sub>3</sub>)NC(Me)C(H)C(Me)N(2,6-Pr<sup>i</sup><sub>2</sub>C<sub>6</sub>H<sub>3</sub>)K·PhCH<sub>3</sub>]:  A Heavy Alkali Metal Diazapentadienyl Complex. Inorg. Chem.. 37. 1998. 10.1021/ic970956j.