Revisiting [Mn(CO)3(η5-nido-7,8-C2B9H11)]-, the Dicarbollide Analogue of [(η5-C5H5)Mn(CO)3]: Reactivity Studies Leading to Boron Atom Functionalization

Treatment of Na 2 [7,8-R 2 - nido -7,8-C 2 B 9 H 9 ] (R = H, Me) with the reagent [Mn(NCMe) 3 (CO) 3 ][PF 6 ] affords the anions [3,3,3-(CO) 3 -1,2-R 2 - closo -3,1,2-MnC 2 B 9 H 9 ] -, typically isolated as Cs + or [N(PPh 3 ) 2 ] + salts. These anions interact with cationic metal fragments {M(PPh 3 )} + (M = Cu, Ag, Au) to give the bimetallic compounds [3,8-{M(PPh 3 )}-8- μ -H-3,3,3-(CO) 3 -1,2-R 2 - closo -3,1,2-MnC 2 B 9 H 8 ], for which the structures of the Cu and Au species (R = H) have been confirmed by X-ray diffraction studies. In contrast, other electrophiles such as H + and Me + abstract hydride from carborane boron vertexes, which in the presence of donors (L) produces the neutral zwitterions [8-L-3,3,3-(CO) 3 -1,2-R 2 - closo -3,1,2-MnC 2 B 9 H 8 ]. The halogenated derivatives [8-X-3,3,3-(CO) 3 -1,2-R 2 - closo -3,1,2-MnC 2 B 9 H 8 ] - (X = Cl, Br, I) of the parent anions are obtained by hydride abstraction in halogenated solvents or by direct reaction with Br 2 or I 2 . Moreover, further cluster functionalization is achieved by treating the 8-iodo species with the Grignard reagents R‘MgBr, leading to the anions [8-R‘-3,3,3-(CO) 3 -1,2-R 2 - closo -3,1,2-MnC 2 B 9 H 8 ] - . When the substitution processes are repeated, the latter series of anions yield compounds with yet more functionality. Crystallographic studies of the boron-substituted derivatives [8-{( E )-N(Me) C(H)Me}-3,3,3-(CO) 3 - closo -3,1,2-MnC 2 B 9 H 10 ], [N(PPh 3 ) 2 ][8-( p -C 6 H 4 Me)-3,3,3-(CO) 3 -1,2-Me 2 - closo -3,1,2-MnC 2 B 9 H 8 ], and [4-{( Z )-N(Me) C(H)Me}-3,3,3-(CO) 3 -1,2,8-Me 3 - closo -3,1,2-MnC 2 B 9 H 7 ] confirmed their structures and the sites of cage substitution.