Boratocarbyne Complexes:Li[Mo{CB(OMe)3}(CO)2{HB(pzMe2)3}] and [K(18-crown-6)][Mo(CBF2OMe)(CO)2{HB(pzMe2)3}] (pz= pyrazol-1-yl).

The successive treatment of [Mo(CBr)(CO)2{HB(pzMe2)3}] (1; pz =pyrazol-1-yl) with nBuLi and B(OR)3(R = Me, iPr) affords,via the lithiocarbyne complex [Mo(CLi)(CO)2{HB(pzMe2)3}] (2), the boratocarbynes Li[Mo{CB(OMe)3}(CO)2{HB(pzMe2)3}] (R =Me, Li[3a]; R = iPr, Li[3b]). The salt Li[3b] readily eliminates LiOiPr to afford the neutral boryl carbyne [Mo{CB(OiPr)2}(CO)2{HB(pzMe2)3}] (4b). The analogous boryl carbyne [Mo{CB(OMe)2}(CO)2{HB(pzMe2)3}] (4a) on treatment with K[HF2] and 18-crown-6 (18C6)provides the structurally characterized difluoro(methoxy)boratocarbynesalt [K(18C6)][Mo(CBF2OMe)(CO)2{HB(pzMe2)3}] ([K(18C6)][6]). [ABSTRACT FROM AUTHOR]