Compounds of Iron, Molybdenum, Tungsten, Rhenium, Platinum, Nickel and Cobalt

Mononuclear Compounds of Iron, Molybdenum, Tungsten, Rhenium, Platinum, Nickel and Cobalt 

Reactions between salts of [ z 7o-7-CB10I b3] and [Fe3(CO)12] afford the mononuclear anionic iron compound [2,2,2-(CO)3-c/oxo-2,l-FeCB10Hn], typically isolated as its [N(PPh3)2]+ salt (11) (Chart 4).14 No anionic triiron complex analogous to 5 and 7 is formed in this reaction. The anionic mononuclear iron, ruthenium and osmium complexes and the previously mentioned neutral mononuclear ruthenium dicarbollide complex 4, obtained from [Ru3(CO)12] and /zfo-7,8-C2B9H13, are iso-lobal with the cyclopentadienide species [Mn(CO)3(ti-C5H5)] and [Fe(CO)3 (tl-C5H5)] +.  

Salts of [ k/o-7-CB10Hh]3 have not been extensively employed as yet to obtain half-sandwich compounds 2-(ligand)B-c/oxo-2,l-MCB10Hn, but their potential as precursors is demonstrated in the synthesis of rhenium and platinum compounds. Thus salts of the dianion [2,2,2-(CO)Tcloso-2,1 -ReCB10H,, ]2 have been prepared by 

Contemporary studies with the nickel system have extended the series of known nickel-monocarbollide anions (Chart 5). The salt [NMe4][2,2-(CNBu )2-c/rt.w-2,1 -NiCBioHn] (17a) was prepared in the original study, using [Ni(CNBul)2(cod)] 

As has been described, the parent monocarbollide-metal carbonyl piano-stool species 2-(CO)n-closo-2,1 -MCB,0II n] 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 dicarbonyl-platinum analogue of compound 18,20 and as mentioned earlier, the manganese analogue of 14 has also briefly been reported.3a A notable absence from this list, however, is any representative of the Group 9 metals. The carbonyl nitrosyl-cobalt complex 21 is very closely related to the hitherto unknown dicarbonyl-cobalt dianion [2,2-(CO)2- 7 9.v 9-2,1 -CoCB10H 11]2 and this species remains an attractive synthetic target. 

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