Synthesis of the manganese-monocarbollide dianion [1-NHBut-2,2,2-(CO)3-closo-2,1-MnCB10H10]2−: Reactions with transition metal cations

Reaction of [Mn(NCMe)3(CO)3][PF6] with Li3[7-NHBut-nido-7-CB10H10] in THF (THF = tetrahydrofuran) affords the twelve-vertex manganacarborane dianion [1-NHBut-2,2,2-(CO)3-closo-2,1-MnCB10H10]2−, isolated as the bis-[N(PPh3)2]+ salt (5a). This species reacts with {Pt(dppe)}2+ (dppe = Ph2PCH2CH2PPh2) to afford the bimetallic complex [1-NH2But-2,3-{Pt(dppe)}-2,2,2-(CO)3-closo-2,1-MnCB10H9] (7) which has an Mn–Pt bond. In contrast, with {Cu(PPh3)}+ the anion of 5a yields a CuMnCu trimetallic compound [1-{NH(But)Cu(PPh3)}-2,3,7-{Cu(PPh3)}-3,7-(μ-H)2-2,2,2-(CO)3-closo-2,1-MnCB10H8] (8) in which one of the Cu centers is bonded to Mn, whilst the other is attached to the pendant NHBut group. Upon treatment with Ag+, compound 5a is oxidized giving the very unusual Mn(III)-carbonyl complex [1,2-μ-NHBut-2,2,2-(CO)3-closo-2,1-MnCB10H10] (9a) in which the carborane ligand formally acts as an eight-electron donor to manganese. The novel structural features of compounds 7, 8, and 9a have been confirmed by X-ray diffraction studies.

The title twelve-vertex manganacarborane anion undergoes a variety of reactions with cationic transition-metal fragments, giving products that range from bimetallic and trimetallic species which retain the Mn(I) oxidation state of the precursor, to an unusual mononuclear Mn(III)-carbonyl complex (shown).Figure optionsDownload as PowerPoint slide