| Summary: | Recent development in the synthesis and characterization of noble-gas compounds is reviewed, i.e., noble-gas chemistry reported in the last five years with emphasis on the publications issued after 2017. XeF<sub>2</sub> is commercially available and has a wider practical application both in the laboratory use and in the industry. As a ligand it can coordinate to metal centers resulting in [M(XeF<sub>2</sub>)<sub>x</sub>]<sup>n+</sup> salts. With strong Lewis acids, XeF<sub>2</sub> acts as a fluoride ion donor forming [XeF]<sup>+</sup> or [Xe<sub>2</sub>F<sub>3</sub>]<sup>+</sup> salts. Latest examples are [Xe<sub>2</sub>F<sub>3</sub>][RuF<sub>6</sub>]·XeF<sub>2</sub>, [Xe<sub>2</sub>F<sub>3</sub>][RuF<sub>6</sub>] and [Xe<sub>2</sub>F<sub>3</sub>][IrF<sub>6</sub>]. Adducts NgF<sub>2</sub>·CrOF<sub>4</sub> and NgF<sub>2</sub>·2CrOF<sub>4</sub> (Ng = Xe, Kr) were synthesized and structurally characterized at low temperatures. The geometry of XeF<sub>6</sub> was studied in solid argon and neon matrices. Xenon hexafluoride is a well-known fluoride ion donor forming various [XeF<sub>5</sub>]<sup>+</sup> and [Xe<sub>2</sub>F<sub>11</sub>]<sup>+</sup> salts. A large number of crystal structures of previously known or new [XeF<sub>5</sub>]<sup>+</sup> and [Xe<sub>2</sub>F<sub>11</sub>]<sup>+</sup> salts were reported, i.e., [Xe<sub>2</sub>F<sub>11</sub>][SbF<sub>6</sub>], [XeF<sub>5</sub>][SbF<sub>6</sub>], [XeF<sub>5</sub>][Sb<sub>2</sub>F<sub>11</sub>], [XeF<sub>5</sub>][BF<sub>4</sub>], [XeF<sub>5</sub>][TiF<sub>5</sub>], [XeF<sub>5</sub>]<sub>5</sub>[Ti<sub>10</sub>F<sub>45</sub>], [XeF<sub>5</sub>][Ti<sub>3</sub>F<sub>13</sub>], [XeF<sub>5</sub>]<sub>2</sub>[MnF<sub>6</sub>], [XeF<sub>5</sub>][MnF<sub>5</sub>], [XeF<sub>5</sub>]<sub>4</sub>[Mn<sub>8</sub>F<sub>36</sub>], [Xe<sub>2</sub>F<sub>11</sub>]<sub>2</sub>[SnF<sub>6</sub>], [Xe<sub>2</sub>F<sub>11</sub>]<sub>2</sub>[PbF<sub>6</sub>], [XeF<sub>5</sub>]<sub>4</sub>[Sn<sub>5</sub>F<sub>24</sub>], [XeF<sub>5</sub>][Xe<sub>2</sub>F<sub>11</sub>][Cr<sup>V</sup>OF<sub>5</sub>]·2Cr<sup>VI</sup>OF<sub>4</sub>, [XeF<sub>5</sub>]<sub>2</sub>[Cr<sup>IV</sup>F<sub>6</sub>]·2Cr<sup>VI</sup>OF<sub>4</sub>, [Xe<sub>2</sub>F<sub>11</sub>]<sub>2</sub>[Cr<sup>IV</sup>F<sub>6</sub>], [XeF<sub>5</sub>]<sub>2</sub>[Cr<sup>V</sup><sub>2</sub>O<sub>2</sub>F<sub>8</sub>], [XeF<sub>5</sub>]<sub>2</sub>[Cr<sup>V</sup><sub>2</sub>O<sub>2</sub>F<sub>8</sub>]·2HF, [XeF<sub>5</sub>]<sub>2</sub>[Cr<sup>V</sup><sub>2</sub>O<sub>2</sub>F<sub>8</sub>]·2XeOF<sub>4</sub>, A[XeF<sub>5</sub>][SbF<sub>6</sub>]<sub>2</sub> (A = Rb, Cs), Cs[XeF<sub>5</sub>][Bi<sub>x</sub>Sb<sub>1-x</sub>F<sub>6</sub>]<sub>2</sub> (x = ~0.37–0.39), NO<sub>2</sub>XeF<sub>5</sub>(SbF<sub>6</sub>)<sub>2</sub>, XeF<sub>5</sub>M(SbF<sub>6</sub>)<sub>3</sub> (M = Ni, Mg, Zn, Co, Cu, Mn and Pd) and (XeF<sub>5</sub>)<sub>3</sub>[Hg(HF)]<sub>2</sub>(SbF<sub>6</sub>)<sub>7</sub>. Despite its extreme sensitivity, many new XeO<sub>3</sub> adducts were synthesized, i.e., the 15-crown adduct of XeO<sub>3</sub>, adducts of XeO<sub>3</sub> with triphenylphosphine oxide, dimethylsulfoxide and pyridine-N-oxide, and adducts between XeO<sub>3</sub> and N-bases (pyridine and 4-dimethylaminopyridine). [Hg(KrF<sub>2</sub>)<sub>8</sub>][AsF<sub>6</sub>]<sub>2</sub>·2HF is a new example of a compound in which KrF<sub>2</sub> serves as a ligand. Numerous new charged species of noble gases were reported (ArCH<sub>2</sub><sup>+</sup>, ArOH<sup>+</sup>, [ArB<sub>3</sub>O<sub>4</sub>]<sup>+</sup>, [ArB<sub>3</sub>O<sub>5</sub>]<sup>+</sup>, [ArB<sub>4</sub>O<sub>6</sub>]<sup>+</sup>, [ArB<sub>5</sub>O<sub>7</sub>]<sup>+</sup>, [B<sub>12</sub>(CN)<sub>11</sub>Ne]<sup>−</sup>). Molecular ion HeH<sup>+</sup> was finally detected in interstellar space. The discoveries of Na<sub>2</sub>He and ArNi at high pressure were reported. Bonding motifs in noble-gas compounds are briefly commented on in the last paragraph of this review.
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