Alkynylselenolatoalkylidynes: [Mo(≡CSeC≡CR)(CO) 2 {HB(pzMe 2 ) 3 }] (R = CMe 3 , SiMe 3 ; pzMe 2 = 3,5-Dimethylpyrazol-1-yl)

The reactions of [Mo(≡CCl)(CO)2{HB(pzMe2)3}] (pz = 3,5-dimethylpyrazol-1-yl) with lithium alkynylselenolates (LiSeC≡CR; R = CMe3, SiMe3) provide the alkynylselenolatoalkylidyne complexes [Mo(≡CSeC≡CR)(CO)2{HB(pzMe2)3}]. Cobalt carbonyl adds across the C≡C rather than the Mo≡C multiple bond to provide [Mo{≡CSeCC(CMe3)Co2(CO)6}(CO)2{HB(pzMe2)3}], which upon reaction with dppm affords the complex [Mo{≡CSeCC(CMe3)Co2(CO)4(dppm)}(CO)2{HB(pzMe2)3}] in addition to traces of the selenium extrusion product [Mo{≡CCC(CMe3)Co2(CO)4(dppm)}(CO)2{HB(pzMe2)3}].