INIDENE COMPLEXES - EXTENSION OF AN ISOELECTRONIC SERIES TO THE 3RD MAIN-GROUP

The reaction of K2[Cr(CO)5] with InCl3, followed by addition of [Bu4N]Br, gives {[(CO)5Cr]2InBr}2- (1), that can be isolated in good yield as its tetrabutylammonium salt. Similarly, the reaction of K2[Cr(CO)5] with TlCl3, after metathesis with [Bu4N]Hal, gives {[(CO)5Cr]2TlHal}2- (Hal = Cl, Br, 1; 2a-c) in yields of around 60%. X-ray analyses show trigonal planar coordination of the bridging elements, In (1) and Tl (2), in all products. Short In-Cr (266 pm, 1) and Tl-Cr (268 pm, 2) bond distances indicate substantial shortening by pi-interactions. Compounds 1 and 2 thus extend the series of ''inidene'' complexes to compounds with third main group bridging elements.