The invention discloses ruthenium alkylidene complexes of the type (PCy.sub.3)(L)Cl.sub.2 Ru(CHPh), where L is a triazolylidene ligand of the general formula: ##STR1## These catalysts have been found to be considerably more active for olefin metathesis at elevated temperatures than the parent catalyst (PCy.sub.3).sub.2 Cl.sub.2 Ru(CHPh)(2). For example, complex 14 (L=1,3,4-triphenyl-4.5-dihydro-1H-triazol-5-ylidene) is able to catalyze the ring-closing metathesis of substituted dienes to give tetra-substituted cyclic olefins in good yield. In addition, this complex demonstrates the analogous stability towards oxygen and moisture exhibited by ruthenium alkylidene 2.

A invenção divulga complexos do alkylidene do ruthenium do tipo (PCy.sub.3)(L)Cl.sub.2 Ru(CHPh), onde L é um ligand do triazolylidene da fórmula geral: ## do ## STR1 Estes catalizadores foram encontrados para ser consideravelmente mais ativos para o metathesis do olefin em temperaturas elevated do que o catalizador do pai (PCy.sub.3).sub.2 Cl.sub.2 Ru(CHPh)(2). Para o exemplo, o complexo 14 (L=1,3,4-triphenyl-4.5-dihydro-1H-triazol-5-ylidene) pode catalyze o metathesis defechamento de dienes substituídos para dar olefins cíclicos tetra-substituídos no rendimento bom. Além, este complexo demonstra a estabilidade analogous para o oxigênio e a umidade exibidos pelo alkylidene 2 do ruthenium.