Zirconium monovalent

Monovalent Halides. Zirconium monochloride [14989-34-5], ZrCl, was discovered during electrorefining studies of zirconium in a SrCl2—NaCl—ZrCl4 melt intended to produce pure ductile hafnium-depleted zirconium from cmde zirconium anodes (180—181). The monochloride is also called Zirklor. It is obtained as black flakes with a graphite sHp-plane behavior and was proposed as a lubricant (182,183). 

Reduction of ZrCl4 with Na/Hg at < -10 °C in the presence of cycloheptatriene gives Zr(i76-C7H8)2 it exhibits a non-parallel arrangement of the cycloheptatrienyl ligands (18-A-VIII) and can be used to prepare a series of zero- and monovalent 16-e zirconium complexes such as Zr(rf-CjH-,)(rf-CjH,)(PMe3), Zi(rf-0,H7)-(tmeda)Cl, and others.72... 

Structures of di- and monovalent zirconium and hafnium compounds contain octahedra, chains, or layers of metal atoms with metal-metal bonds. It is this that differentiates these compounds from those of M (MX3 or molecular M2X6L4 complexes) with isolated M-M bonds. A recent reinvestigation of the ZrL structure showed two distinct Zr-Zr distances (3.507 and 3.172 A) the latter is typical for a Zr-Zr bond (see Bond Length). 

Zirconium and hafnium tetrahalides form a variety of double halides with metal halides. The most widespread composition is Q2MX6 (Q = monovalent cation) but the QMX5 complexes and fluoride complexes Q3MF7 and Q4MF8 are also documented. Q2MX6 chlorides and bromides consist of [MXe] octahedra. The complex chloride anions [MCls]" and [MCle]" have been detected in molten MCI4 (equation 15) ... 

ZrFg]" " ones when the ionic radii of the monovalent cation increase (i.e., from Li-f to Na-I- and then to K+). In agreement with F high-temperature NMR experiments, MD calculations highlight an increase of the number of bridging fluorines between zirconium fluorides complexes and a contraction of the average... 

Doping of rare-earth elements into a sulfate electrolyte also contributes appreciably to obtaining a good ionic conductor similar to the case for stabilized zirconia. Doping causes retention of the high-temperature phase for superior ionic conduction. One different feature between stabilized zirconia and the sulfate electrolyte is that the trivalent rare earth substitutes a monovalent cation site in the sulfate electrolyte, while the tetravalent zirconium site is replaced with trivalent yttrium in zirconia. In the sulfate electrolyte, the vacancy produced is not an anion vacancy but a cation vacancy. Their production also enhances the cationic conduction which reflects in the improvement of the sensing characteristics. 

---