Manganese piano stool complex

Silane complexes were the first species formed solely by coordination of a metal to a CT-bond. The bonding in these complexes was recognized to be imusual and was described as a hydride bridged M-Si bond, instead of the later language of an X-H cr-bond coordinated to a transition metal. The first monomeric example of such a complex was the manganese piano stool complex shown in Figure... 

As has been deseribed, the parent monoearbollide-metal earbonyl piano-stool species [2-(CO) -c/oi o-2,l-MCBioHii] are now known for all of the metals M = Mo (12), W (13), Re (14), Fe (11), Ru (6), Os (8), and Ni (18). Evidence also exists for a diearbonyl-platinum analogue of eompound 18, ° and as mentioned earlier, the manganese analogue of 14 has also briefly been reported. A notable absenee from this list, however, is any representative of the Group 9 metals. The earbonyl nitrosyl-cobalt complex 21 is very elosely related to the hitherto unknown dicarbonyl-cobalt dianion [2,2-(CO)2-c/oi o-2,l-CoCBioHii] and this species remains an attractive synthetie target. 

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