A Five-Coordinate Compound with Inverted Ligand Field: An Unprecedented Geometry for Silver(III)

By using suitable synthetic procedures, we have first isolated the square-planar organosilver(III) compounds [PPh4][trans-(CF3)(2)AgX2] [X=Cl (1 a), Br (2 a)]. The geometry and stereochemistry of the chloro-derivative 1 a have been unambiguously established by single-crystal X-ray diffraction (SC-XRD) methods. Following our calculations on the relative stability of the cis-/trans-[(CF3)(2)AgX2](-) couples (X=F, Cl, Br, I), the experimentally obtained compounds 1 a and 2 a appear to be kinetically favored stereoisomers. They display some tendency to associate an additional X- ligand affording rare five-coordinate Ag-III species [(CF3)(2)AgX3](2-). Interestingly, compound [PPh4](2)[(CF3)(2)AgBr3] (3) has been identified by SC-XRD methods as the first Ag-III derivative with trigonal symmetry in general and trigonal bipyramidal geometry in particular. This unusual five-coordinate species also exhibits inverted ligand field.

Automated summary

By utilizing suitable synthetic procedures, researchers isolated square-planar organosilver(III) compounds and determined their geometry and stereochemistry. The experimentally obtained compounds exhibit kinetic preference for specific stereoisomers and show a tendency to form rare five-coordinate Ag-III species. Additionally, a unique silver(III) derivative with trigonal bipyramidal geometry and inverted ligand field has been identified for the first time.