10-Vertex Manganese−Dicarbollide Complexes from a Monocarbon Precursor. Synthesis and Cluster Vertex Functionalization of [1-OH-2,2,2-(CO)₃-<i>closo</i>-2,1,10-MnC₂B₇H₈]⁻

Reaction between [NBun4][closo-1-CB7H8] and [Mn2(CO)10] in THF (THF = tetrahydrofuran) at reflux temperatures, or at room temperature with ultraviolet irradiation, followed by addition of [N(PPh3)2]Cl, affords the manganese−dicarbollide salt [N(PPh3)2][1-OH-2,2,2-(CO)3-closo-2,1,10-MnC2B7H8] (1). Addition of NOBF4 to 1 gives the neutral species [1-OH-2,2-(CO)2-2-NO-closo-2,1,10-MnC2B7H8] (2), which readily undergoes CO substitution with PEt3 in the presence of Me3NO to yield [1-OH-2-CO-2-NO-2-PEt3-closo-2,1,10-MnC2B7H8] (3). Protonation of 1 in the presence of dialkyl sulfides SR2 affords the neutral complexes [1-SR2-2,2,2-(CO)3-closo-2,1,10-MnC2B7H8] [R = Me (4); SR2 = S(CH2)4 (5); R = {CH2CHCH2} (6)]; the synthesis of 5 is accompanied by formation of a boron-substituted relative, [1-OH-6-{S(CH2)4}-2,2,2-(CO)3-closo-2,1,10-MnC2B7H7] (7). Addition of Me3NO to 6 in CH2Cl2 produces the anions [1-(SCH2CHCH2)-2,2,2-(CO)3-closo-2,1,10-MnC2B7H8]− and [1,2-σ:η2-(SCH2CHCH2)-2,2-(CO)2-closo-2,1,10-MnC2B7H8]−, isolated as the [N(PPh3)2]+ salts 10 and 11, respectively. Iodinated derivatives of 1 are obtained by direct reaction with I2: an equimolar reaction yields two species, [N(PPh3)2][1-I-2,2,2-(CO)3-closo-2,1,10-MnC2B7H8] (12) and [N(PPh3)2][1-OH-6-I-2,2,2-(CO)3-closo-2,1,10-MnC2B7H7] (13), whereas treatment with excess I2 affords [N(PPh3)2][1,6,9-I3-2,2,2-(CO)3-closo-2,1,10-MnC2B7H6] (14) as the only product. When 12 was heated with Cu powder in refluxing DMF (DMF = N,N-dimethylformamide) the “parent” unsubstituted compound [N(PPh3)2][2,2,2-(CO)3-closo-2,1,10-MnC2B7H9] (15) was the sole product. Further cluster functionalization was achieved by treating 14 with the Grignard reagent (p-tol)MgBr (p-tol = 4-Me-C6H4-), leading to [N(PPh3)2][6,9-(p-tol)2-2,2,2-(CO)3-closo-2,1,10-MnC2B7H7] (16). The latter reacts with NOBF4 in CH2Cl2 to form neutral [6,9-(p-tol)2-2,2-(CO)2-2-NO-closo-2,1,10-MnC2B7H7] (17). X-ray diffraction studies have confirmed the structural details of compounds 1, 2, 7, 8, 11−13, 15, and 17.