Dithiene complexes

Fig. 9. Examples of dyes used in optical disks. (14), pentamethine cyanine [36536-22-8] (1 )> nickel dithiene complex [38465-55-3] and (16) lR-810.

Recent Advances in the Chemistry of Transition Metal Complexes of Unsaturated Bidentate Sulfur Donor Ligands (Metal Dithienes)... 

Ti etal dithienes (J), which are known also as dithiolenes (2), comprise a group of neutral complexes of metals with ligands derived from 1,2-dithiodiketones (l) or cis-l,2-ethylenedithiols (2). The complexes... 

Complexes of most transition metals have become accessible by improved methods of synthesis. The most general method utilizes acyloins as starting materials which react first with P4S10 to afford thiophosphates of substituted cis-l,2-ethylenedithiols. The latter react with metal salts in aqueous solution to give metal dithienes (4),... 

The infrared spectrum of 19 is typical of a 1,2-ethylenedithiolato complex rather than of a dithiene and, thus, permits the classical formulation. This is consistent with the absence of typical dithiene reactivity. Complex 19 does not undergo reversible electron transfer reactions, for example (16),... 

Complexes of 1,2-dithiotropolone were predicted to possess properties different from metal dithienes, the ligand being a typical odd system (I). Forbes and Holm (27) reported recently the synthesis of the ligand and a number of complexes which confirm this proposal. 

I express my thanks and appreciation to my co-workers and colleagues who have participated in the work on metal dithienes. At Munich, V. P. Mayweg, W. Heinrich, and H. W. Finck. At Shell Development Co., E. J. Rosa, A. E. Smith, and D. C. Olson. At La Jolla, H. N. Rabino-witz, R. P. Murillo, and R. K. Y. Ho. Particular thanks are also extended to I. C. Paul (Urbana, 111.) for confirming the structure of complex 36 by single crystal x-ray diffraction. 

Metal complexes of 1,2-dithiolates (or dithienes) have been of great interest to inorganic chemists because of their redox properties. Schlapfer and Nakamoto prepared a series of complexes of the type [Ni(S2C2R2)2]" where R is H, Ph, Cp3, and CN and n is 0, —1, or -2, and carried out normal coordinate analysis to obtain rough estimates of the charge distribution based on the calculated force constants. 

The name dithiolenes was chosen to describe these compounds without prejudice towards one of the limiting structures. The equally descriptive name dithienes has been coined for the same reason, but it is now rarely used. The less fortunate description of dithiolenes as dithiolato complexes is found occasionally, but it does have a much more restricted meaning (see Section 16.5.2.4) and should be avoided for the neutral species. Nevertheless, Chemical Abstracts refers to dithiolenes as bis[l,2-ethenedithiolato(2—)] complexes of the respective central metal, for example the parent nickel complex (4) is listed as nickel, bis[l,2-ethenedithiolato(2—)-5,S ]- however, depending on the date of the CA issue, its tetraphenyl derivative will be found either under bis[a,a -stilbenedithiolato(2 — )]-nickel or as bis[ 1,2-diphenyl-1,2-ethenedithiolato(2 -)-S,S"]-nick-el. Even less appropriate are the CA names for the radical anions and dianions of the dithiolenes, which are referred to as metallates(—) and metallates(2 —) of the respective ligands the dianion of the parent nickel dithiolene thus is found as bis[l,2-ethenedithiolato(2—)]-nickelate(2—), a name which has little to do with the electronic structure of the compound. 

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