The original "chop-chop." reaction reported by Schrock [J. Am. Chem. Soc. 1982, 104,4291] involving W-2((OBu)-Bu-t)(6) and organic nitriles, RC N to give the metal alkylidyne and nitride products ((BuO)-Bu-t)(3)WC R and (tBuO)(3)WC N, has been examined by a density functional theory based calculation where the bulky (BuO)-Bu-t ligands have been substituted by MeO. The reaction between W-2(OMe)(6) and MeCN proceeds via a ditungstaazacyclobutadiene intermediate having a planar W2CN core, I, with a structure related to that seen for MO2((OCH2Bu)-Bu-t)(6)(mu-NCNMe2). Another possible intermediate having a pseudo tetrahedral W2CN core, II; a ditungstaazatetrahedrane was examined and shown to have a higher energy. The interconversion of I and II was found to be energetically unfavorable with respect to their formation of metathesis products. The highest energy transition state involving the conversion of I to products was comparable to that for the conversion of II to products but the initial formation of I from the reaction between W-2(OMe)(6) and MeCN was favored over the formation of II. The related reaction between Mo-2(OMe)(6) and MeCN was shown to be thermodynamically unfavorable with respect to either adduct formation or metathesis products. However the reaction between Mo-2(OMe)(6) and Me2NCN did yield a thermodynamically favored 1:1 adduct with a structure related to I.