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High-energy relatives of benzene have captured the imagination of chemists, especially those with cumulative double bonds which feature strained ring structure and lack any aromaticity stabilization. The integration of transition metals and Group 14 elements into six-membered cycloallene rings has been achieved by a [5+1]-cycloaddition of diethynylsilane or diethynylgermane with simple transition metal complexes. Experimental and computational studies demonstrate the stability of these unprecedent cycloallenes, i.e. metalla-isosilabenzenes and metalla-isogermabenzenes, may root in the decreasing strain on the cumulative double bonds. More details are discussed in the article by Zhang et al. on page 1121—1127.