The reaction of TaCl 5 with 2 equiv of Li 2 [C 2 B 9 H 11 ] in refluxing toluene yields {(µ-H)-(C 2 B 9 H 10 ) 2 }TaCl 2 (1), which contains the unusual linked bis(carboranyl) ligand [(µ-H)-(C 2 B 9 H 10 ) 2 ] 3-, which is formed by formal oxidative coupling of two C 2 B 9 H 11 2ligands. Alkylation of 1 with ZnMe 2 yields {(µ-H)(C 2 B 9 H 10 ) 2 }TaMeCl (2), which retains the linked bis(carboranyl) ligand.

1-Methylindole was dimercurated upon treatment with mercuric acetate (2 equiv) in 1:1 ethanol−diethyl ether to afford 2,3-bis(acetoxymercurio)-1-methylindole (88%). 2,3-Bis(acetoxymercurio)-1-methylindole was converted to 2,3-bis(chloromercurio)-1-methylindole (92%) by refluxing with excess lithium chloride in methanol for 48 h. Treatment of 2,3-bis(chloromercurio)-1-methylindole with trimethylaluminum (4 equiv) in hexane afforded dimeric 2-(chloromethylaluminio)-3-(dimethylaluminio)-1-methylindole in 93% yield. The structure of dimeric 2-(chloromethylaluminio)-3-(dimethylaluminio)-1-methylindole was established by NMR, IR, and microanalysis and by an X-ray structure determination. Dimeric 2-(chloromethylaluminio)-3-(dimethylaluminio)-1-methylindole shows hindered rotation of the dimethylaluminio groups, with a barrier to rotation of 14.2 ± 0.2 kcal/mol. The molecular structure of dimeric 2-(chloromethylaluminio)-3-(dimethylaluminio)-1-methylindole was determined by X-ray crystallography and consists of a 2,3-dialuminated indole connected by a C4Al2 ring in a chair conformation. The C4Al2 ring is composed of two chloromethylaluminio groups bridging between the 2-position of one indole fragment and the 3-position of another. A dimethylaluminio group is bonded to the carbon at the 3-position in each indole ring, and a bridging chloride is situated between the dimethylaluminio and chloromethylaluminio units in each half of the dimeric structure.

The synthesis of 1,4-bis(chloromagnesio)-2,5-di-tert-butylbenzene was conducted by treating 1,4-bis(chloromercurio)-2,5-di-tert-butylbenzene with methylmagnesium chloride. The dimagnesiated compound was characterized by hydrolysis, halogenation, and treatment with allyl bromide. NMR spectra suggest that 1,4-bis(chloromagnesio)-2,5-di-tert-butylbenzene exists as a mixture of oligomers.

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