“…As part of our ongoing theoretical work about the reaction mechanism of olefin addition to metal@E double bonds [3a,4a,b,5,7-13] we present a comparative study of [2+2] and [3+2] ethylene additions to W(@O) 2 (CH 3 ) 2 (W2), (O@)W(@NH)(CH 3 ) 2 (W3), (H 2 C@)W(@NH)(CH 3 ) 2 (W4), (H 2 C@) W(@CH 2 )(CH 3 ) 2 (W5) and (HN@)W(@NH)(CH 3 ) 2 (W6). We compare the results with our previously published data for the ethylene addition to (O@)W(@CH 2 )(CH 3 ) 2 (W1) [10a], its lighter homologs [10b], and similar group-7 [9,11], group-8 [7,8,12], and group-9 [13] compounds. Due to the diversity of the compounds, we only consider [3+2] and [2+2] pathways.…”