Resonance Raman study of (h2-TCNE)M(CO)5 (M = Cr, W; TCNE = tetracyanoethene). Evidence for an olefin-complex $\rightarrow$ metallacyclopropane transition upon low-energy metal-to-ligand charge-transfer excitation. Journal of Organometallic Chemistry, (409)1-2:189--195, 1991. [PUMA: Raman Raman;charge Raman;chromium Raman;hybridization Raman;tungsten carbonyl carbonyltetracyanoethane charge chromium complex metal tetracyanoethane transfer transfer;cyanoethane tungsten]