Observation of gas phase organometallic free radicals: Monomethyl derivatives of calcium and strontium

We have observed the organometallic free radicals CaCH3 and SrCH3 by the gas phase reaction of Ca or Sr metal vapor with Hg(CH3)2 and several other CH3 containing oxidants. The positions of the à 2E–X̃ 2A1 and B̃ 2A1–X̃ 2A1 transitions were determined, as well as several vibrational frequencies. The observation of predissociation in the à 2E state gives an upper limit of 46 kcal/mol (43 kcal/mol) to the bond dissociation energy for CaCH3 (SrCH3).