Thiocyanate coordination chemistry

The majority of U(V1) coordination chemistry has been explored with the trans-ddo s.o uranyl cation, UO " 2- The simplest complexes are ammonia adducts, of importance because of the ease of their synthesis and their versatihty as starting materials for other complexes. In addition to ammonia, many of the ligand types mentioned ia the iatroduction have been complexed with U(V1) and usually have coordination numbers of either 6 or 8. As a result of these coordination environments a majority of the complexes have an octahedral or hexagonal bipyramidal coordination environment. Examples iuclude U02X2L (X = hahde, OR, NO3, RCO2, L = NH3, primary, secondary, and tertiary amines, py n = 2-4), U02(N03)2L (L = en, diamiaobenzene n = 1, 2). The use of thiocyanates has lead to the isolation of typically 6 or 8 coordinate neutral and anionic species, ie, [U02(NCS)J j)/H20 (x = 2-5). 

A definite nitrido coordination chemistry has grown up including abstraction of sulphur from thiocyanate (Figure 1.74). 

Coordination chemistry of cyanate, thiocyanate and selenocyanate ions. A. H. Norbury, Adv. Inorg. Chem. Radiochem., 1975,17,232-386 (825). 

Coordination Chemistry of the Cyanate, Thiocyanate, and Selenocyanate Ions A. H. Norbury... 

The complex [Cr(THF)3Cl3] was first prepared in 1958.802 However pure bromide, iodide and thiocyanate complexes were reported only in 1983.803 The preparation of [Cr(THF)6]3+ by the reaction of [Cr(THF)3Cl3] with AgBF4 in THF was attempted only an impure brown/pink oil was obtained. The tris complexes are useful starting materials in both organometallic and coordination chemistry. 

The coordination chemistry of the cyanate, thiocyanate and selenocyanate ligands has been recently reviewed.1874 Platinum(II) forms the complex ion Pt(SCN)2-, and the corresponding homoleptic platinum(IV) complex Pt(SCN)i can be prepared. Numerous mixed ligand complexes of platinum(II) are known containing the thiocyanate ligand and other ligands, although there are fewer platinum(IV) examples. 4... 

Much discussion on the coordination chemistry of the thiocyanate ligand centers on its function as an ambidentate ligand. For coordination to platinum both N-bonded and S-bonded thiocyanate ligands are found and the small energy difference between the two bonding modes leads to small effects such as steric and electronic factors, as well as solvent changes, causing conversion between S- and N-bonded thiocyanate. 

Hexavalent. The majority of An(VI) coordination chemistry with N-donors has been explored with the uranyl cation, 50i. Stable adducts with the hgands discussed in the tri- and tetravalent complexes have been described, for example, U02X2L (X = halide, OR, NO3, RCO2). The coordination numbers observed for these complexes are typically 6, 7, or 8 with octahedral, pentagonal bipyramidal, or hexagonal bipyramidal geometries, respectively. Neutral and anionic thiocyanates have also been isolated, for example [U02(NCS)j2- yH20(x = 2 5). 

D. A. Buckingham, Linkage isomerism of thiocyanate bonded to cobalt(IIl), in Coordination Chemistry, A Century of Progress , ACS Symposium Series 565, ed. G. B. Morgan Kaufmann, American Chemical Society, Washington, DC, 1994, p. 256. 

COORDINATION CHEMISTRY OF THE CYANATE, THIOCYANATE, AND SELENOCYANATE IONS... 

Previously, reviews have appeared on the crystal chemistry of thiocyanate and selenocyanate coordination compounds (612), selenocyanate complexes 334), the stability and formation of thiocyanate complexes 637), the chalcogenocyanates in coordination chemistry 474), and the infrared spectra of thiocyanate and related complexes 57). Other reviews that are largely devoted to aspects of the chemistry of the chalcogenocyanates have appeared on organometallic pseudo-... 

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