The chetale complex [OsCl2(iPr2PCH2CH2OMe-κ2P,O)2] (1) reacted with the propargylic alcohol HC≡CCPh2(OH) to give the vinylidene osmium(II) derivative [OsCl2{═C═CHCPh2(OH)}(iPr2PCH2CH2OMe-κP)(iPr2PCH2CH2OMe-κ2P,O)] (2), which upon treatment with HCl in benzene was transformed to the carbyne complex fac-[OsCl3(≡CCH═CPh2){iPr2PCH2CH2OMe-κP}2] (3a). Thermal rearrangement of 3a led to the formation of the mer-isomer 3b. Reactions of either [OsH2Cl2(iPr2PCH2CO2Me-κP)2] (4) or [OsCl2(iPr2PCH2CO2Me-κ2P,O)2] (5) with alkynols HC≡CCPh(R)OH (R = Ph, Me, H) gave the vinylcarbyne complexes trans,trans-[OsCl2{≡CCH═C(Ph)R}{iPr2PCH2CO2Me-κP}{iPr2PCH2C(═O)O-κ2P,O}] (6−8) by converting one of the phosphinoester ligands into a phosphinoacetate moiety. The six-coordinate carbyne(hydrido) osmium(II) compound [OsHCl2{≡CCH═CPh2}(PiPr3){iPr2PCH2CH2NMe2-κP}] (10) was obtained from [OsH2Cl2(PiPr3)(iPr2PCH2CH2NMe2)] (9) and HC≡CCPh2(OH).