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Reactions of the Dianion [1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H9]2- with Transition-Metal Cations:  Facile Insertion and Then Extrusion of Cluster Vertexes

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posted on 18.04.2005, 00:00 by Shaowu Du, John C. Jeffery, Jason A. Kautz, Xiu Lian Lu, Thomas D. McGrath, Thomas A. Miller, T. Riis-Johannessen, F. Gordon A. Stone
The manganacarborane dianion in [N(PPh3)2][NEt4][1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H9] (1b) reacts with cationic transition metal−ligand fragments to give products in which the electrophilic metal groups (M‘) are exo-polyhedrally attached to the {closo-1,2-MnCB9} cage system via three-center two-electron B−H ⇀ M‘ linkages and generally also by Mn−M‘ bonds. With {Cu(PPh3)}+, the Cu−Mn−Cu trimetallic species [1,6-{Cu(PPh3)}-1,7-{Cu(PPh3)}-6,7-(μ-H)2-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H7] (3a) is formed, whereas reactions with {M‘(dppe)}2+ (M‘ = Ni, Pd; dppe = Ph2PCH2CH2PPh2) give [1,3-{Ni(dppe)}-3-(μ-H)-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H8] (5a) and [1,3,6-{Pd(dppe)}-3,6-(μ-H)2-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H7] (5b), both of which contain M‘−Mn bonds. The latter reaction with M‘ = Pt affords [3,6-{Pt(dppe)}-3,6-(μ-H)2-1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H7] (6), which lacks a Pt−Mn connectivity. Compound 6 itself spontaneously converts to [1-Ph-2,2,2-(CO)3-8,8-(dppe)-hypercloso-8,2,1-PtMnCB9H9] (7b) and thence to [3,6,7-{Mn(CO)3}-3,7-(μ-H)2-1-Ph-6,6-(dppe)-closo-6,1-PtCB8H6] (8). This sequence occurs via initial insertion of the {Pt(dppe)} unit and then extrusion of {Mn(CO)3} and one {BH} vertex. In the presence of alcohols ROH, compound 6 is transformed to the 7-OR substituted analogues of 7b. X-ray diffraction studies were essential in elucidating the structures encountered in compounds 58 and hence in understanding their behavior.