“…The first part focuses on preparation of silyl alkylidene complexes (Me 3 ECH 2 ) 2 Ta(]CHEMe 3 )(SiR 3 ) [R 3 ¼ (SiMe 3 ) 3 , E ¼ C, 3a, Si, 3b; R 3 ¼ Bu t Ph 2 , E ¼ C, 4a, Si, 4b] [12,28] and studies of pathways in the formation of the silyl alkylidene (Me 3 SiCH 2 ) 2 Ta(]CHSiMe 3 )-[Si(SiMe 3 ) 3 ] (3b) [28] as well as alkyl alkylidenes (Me 3 ECH 2 ) 3 Ta] CHEMe 3 (E ¼ C, 5a; Si, 5b) [13,41]. The second part discusses the tautomerization of silyl alkylidyne (Me 3 CCH 2 ) 2 W(^CCMe 3 )(SiBu t Ph 2 ) (6a) with bis-alkylidene (Me 3 CCH 2 )W(]CHCMe 3 ) 2 (SiBu t Ph 2 ) (6b) [32,38] as well as (Me 3 SiCH 2 ) 3 W(^CSiMe 3 )(PR 3 ) [R 3 ¼ Me 3 , 7a; Me 2 Ph, 8a; Me 2 (CH 2 ) 2 PMe 2 (DMPE-P), 9a] with (Me 3 SiCH 2 ) 2 W(]CHSiMe 3 ) 2 (PR 3 ) (R 3 ¼ Me 3 , 7b; Me 2 Ph, 8b; DMPE-P, 9b) [P refers to a dangling P atom in Me 2 P(CH 2 ) 2 PMe 2 ] [37,39,42]. The conversion of the tungsten phosphine tautomerization mixtures to alkyl alkylidene alkylidyne (Me 3 SiCH 2 )W(] CHSiMe 3 )(^CSiMe 3 )(PR 3 ) 2 [(PR 3 ) 2 ](PMe 3 ) 2 , 10; (PMe 2 Ph) 2 , 11; DMPE, 12], including its pathway [40], will also be presented.…”