methyl-magnesium iodide in diethyl ether byproducts: CH4, MgClI, C2H5I; addn. of B10H14 soln. to Grignard reagent (O. degree.C, 2 min), then addn. of 6-chlorodecaborane (0°C), refluxing (12 h); removal of volatiles (0.01 mm Hg, 25 - 40°C, 12 h), chromy. (silica gel/hexane : benzene = 75 : 25);