in dichloromethane (N2 or Ar); a soln. of Fe complex added to a suspn. of B complex at -78°C, warmed to 20°C over 30 min, stirred for 3 h; filtered, layered with hexanes;

in dichloromethane (N2 or Ar); a soln. of Fe complex added to a suspn. of B complex at -78°C, warmed slowly to 20°C, reacted for 72 h; filtered, evapd. (vac.), recrystd. (hexanes, -30°C); obtained as a mixt.;