Platinum polynuclear carbonyl anions

Fig. 12. Infrared spectra of rhodium and platinum polynuclear carbonyl anions in the carbonyl stretching region (tetrasubstituted ammonium or phosphonium salts in THF). MA/NC, ratio of number of metal atoms to the number of negative charges.

No reactions of complexes 62 and 63 have been reported. Palladium and platinum form no well-defined dinitrogen complexes. However, until relatively recently there were few carbonyl complexes of palladium and platinum. This has changed rapidly with the preparation of a wide variety of compounds such as dinuclear complexes, e.g., [M2Cl2(ju,-CO)-(ju. -dppm)2] where M = Pd, Pt, and neutral and anionic polynuclear complexes such as [Os2(CO)6 /t-Pt-(CO)(PPh3) 2] and [Pt9(CO)i8]. The absence of simple, mononuclear palladium and platinum dinitrogen complexes should not be construed as evidence that this is a barren area for research. 

Transition metals with odd atomic numbers cannot achieve the expected FAN in monomeric compounds. In cases where carbonyls of these elements are known, the compormds contain more than one metal atom and metal-metal bonds these effectively contribute one extra electron to each metal Mn2(CO)io, Co2(CO)s. Many polynuclear metal carbonyls are known. The largest metal cluster that has been characterized is a polynuclear platinum carbonyl anion,... 

In this section, we consider polynuclear carbonyl compounds that contain only platinum we consider polynuclear carbonyls that contain platinum and other metals in Section 8.07.1.6. We further split up the discussion on the platinum only compounds into three groupings the homoleptic carbonyl anions, the mixed ligand triangular compounds and assorted others. 

Polynuclear anionic metal carbonyl compounds are usually prepared by reduction reactions of metal carbonyls M(CO) with such reducing agents as the alkali metals, NaBH4 in ethers, hydrocarbons, liquid ammonia, and similar solvents [see, for example, reactions (2.54), (2.55), (2.84), (2.89), (2.95>-(2.102), and (2.108)-(2.113)]. In alkali medium the metal carbonyls may be reduced by certain solvents (e.g., alcohols) or by the CO ligand itself, and in the presence of Lewis bases the carbonyls disproportionate to give anionic clusters. The mixed metal clusters containing platinum and rhodium are formed by reduction reactions of chloro complexes... 

---