Reaction of tetracyanoethylene with the thiolato-bridged d8 diiridium complexes [Ir(.mu.-S-tert-Bu)(CO)(PR3)]2, R = Me, Ph and OMe. Crystal structure of the complex [Ir(.mu.-S-tert-Bu)(CO)(P(OMe)3)]2[C(CN)2]2

Tetracyanoethylene (TCNE): The Characteristic Geometries and Vibrational Absorptions of Its Numerous Structures

Tetracyanoethylene (TCNE) undergoes numerous reactions and is reported to exist in many structural motifs. Identification of these forms and motifs can be challenging. Nonetheless, the number of nu(CN) absorptions and their frequencies provide insight with respect to the specific forms and charge on the TCNE fragment. Particularly informative is the average of the fundamental nu(CN) bands, as well as the length of the central C-C bond. This Review discusses the assignment of structure and formal charge for TCNE-containing compounds. Scrutiny of previous assignments reveals some discrepancies which are discussed, and provides a basis for further study of TCNE structure-function relationships. Several multimetal complexes with bridging [TCNE](z) units exhibit mixed valency and extensive delocalization. The scarcity of suitable model compounds, especially those with M(d(pi-pi*)) backbonding to the CN groups, have thwarted the detailed description of these valence ambiguous compounds; thus, new well-characterized polynuclear compounds are needed.

A Room-Temperature Molecular/Organic-Based Magnet

The reaction of bis(benzene)vanadium with tetracyanoethylene, TCNE, affords an insoluble amorphous black solid that exhibits field-dependent magnetization and hysteresis at room temperature. The critical temperature could not be estimated as it exceeds 350 kelvin, the thermal decomposition temperature of the sample. The empirical composition of the reported material is V(TCNE)x.Y(CH(2)Cl(2)) with x approximately 2 and Y approximately 1/2. On the basis of the available magnetic and infrared data, threedimensional antiferromagnetic exchange of the donor and acceptor spins resulting in ferrimagnetic behavior appears to be the mode of magnetic coupling.