Iridium, linear chain

The spectacular iridium compound HH,HT,HH-[Ir6(/t-OPy)6(I)2(CO)i2] 231 containing an unprecedented almost linear metal chain made up of six iridium atoms has been prepared by Tejel et al. by oxidation of [Ir2(/t-OPy)2(CO)4] with iodine at 0°C in toluene. The formal oxidation state of the iridium atoms is 1.33. The new hexairidium compound has been characterized by X-ray diffraction analysis showing a linear array of iridium-bonded atoms with an HT-[Ir2(/t-OPy)2(CO)4] complex sandwiched in between two HH-[Ir2(/t-OPy)2(I)(CO)4] units (Figure 18). Complex 231 represents the longest polyiridium chain complex so far know. Other polyiridium species with as many as four iridium atom chain have been reported, see Ref 112,112a,l 12b... 

Vaska-type iridium compounds Ir(CO)Cl(PR3)2 bind readily and reversibly to fullerenes via the iridium atom. Flexible, aromatic substituents on both phosphorus atoms then may accommodate interactions with the convex exterior of Ceo- As a result linear fullerene chains precipitate as black crystallites (Figure 5.37). 

X-ray structure revealed the hexametallic chain formed by an almost linear array in which two A isomers sandwich a B isomer (Figure 27). The six iridium atoms are linked by metal-metal bonds, two of whieh are unsupported. The unsupported Ir-Ir distances are (range 2.7757(14) 2.7929(14) A) longer... 

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