Nickel bis(dimethylglyoximate) is the

coordination complex A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many ...

with the formula Ni NC(CH₃)C(CH₃)NOHsub>2. The compound is a bright red solid. It achieved prominence for its use in the qualitative analysis of nickel.

Structure

The geometry of the nickel(II) ion is square planar. It is surrounded by two equivalents of the

conjugate base A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid donates a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a ...

(dmgH⁻) of

dimethylglyoxime Dimethylglyoxime is a chemical compound described by the formula CH3C(NOH)C(NOH)CH3. Its abbreviation is dmgH2 for neutral form, and dmgH− for anionic form, where H stands for hydrogen. This colourless solid is the dioxime derivative of the dike ...

(dmgH₂). The pair of organic ligands are joined through

hydrogen bond In chemistry, a hydrogen bond (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing a ...

s to give a

macrocyclic ligand In coordination chemistry, a macrocyclic ligand is a macrocyclic ring having at least nine atoms (including all hetero atoms) and three or more donor sites that serve as ligands that can bind to a central metal ion. Crown ethers and porphyrins ar ...

. The complex is distinctively colored and insoluble leading to its use as a

chelating agent Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are ...

in the

gravimetric analysis Gravimetric analysis describes a set of methods used in analytical chemistry for the quantitative determination of an analyte (the ion being analyzed) based on its mass. The principle of this type of analysis is that once an ion's mass has been ...

of nickel. The use of dimethylglyoxime as a reagent to detect

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...

was reported by L. A. Chugaev in 1905.{{cite journal , title = Über ein neues, empfindliches Reagens auf Nickel, first=Lev , last = Tschugaeff , journal = Berichte der Deutschen Chemischen Gesellschaft , volume = 38 , issue = 3 , pages = 2520–2522 , year = 1905, language=de, trans-title=About a new, sensitive reagent on nickel , url = https://zenodo.org/record/1426158 , doi = 10.1002/cber.19050380317

References

Nickel complexes