Manganese complexes carbyne

Additional developments in the synthesis of enediyne motifs, beyond the now well-established Pd-catalyzed routes, have recently been reported. Casey et al. (377, 399) demonstrated that cw-enediyne complexes can be readily obtained via dimerization of Cp(CO)2Re-aIkynylcarbene complexes at 100°C (cf. Fig. 27), as well as from the addition of a,oc)-diynes to manganese carbyne complexes that rearrange to enediynes below room temperature. In parallel, Cummins and co-workers have demonstrated that sequential reductive coupling of Mo(IV) acetylides and alkyne metathesis can also be used as a novel route to both ( )- and (Z)-enediyne constructs (523). 

Mixed tetranuclear Mu2lr2 clusters incorporating either fi- or /t3-benzylydine ligands have been reported from the reaction of (PPN)Ir(CO)4 and the manganese carbyne complex [Cp(CO)2Mn( CC6H5)]BBr. ... 

The nucleophilic character of the allenylidene Cp was experimentally demonstrated for the first time by N. E. Kolobova and co-workers in 1984, who obtained alkenyl-carbyne complexes [MnCp sCC(H)=CR2 (CO)2][X] (R = t-Bu, Ph X = Cl, BF4, CF3C02 ) by treatment of the corresponding neutral manganese(I) alleny-lidenes [MnCp(=C=C=CR2)(CO)2] with Brpnsted acids HX [229]. Since then, a... 

Electrophilic attack on //-vinylidene complexes can occur either on the methylene carbon, or at the metal-metal bond. With the manganese complexes (45, R = H or Me), protonation affords the//-carbyne complexes (46), which in the case of R = Me, exist in the stereoisomeric forms shown (57). Interconversion of the two forms is slow at room temperature ... 

The carbyne complex 319 reacts with CO to give 320 °, which results from a double CO insertion and PMes migration, while 321 reacts with the manganese carbonyl complex 322 in refluxing toluene to give 323 °°. 

The reactions of cationic carbyne complexes of manganese with X = C bonds are strongly substrate- and concentration-dependent. The comi unds may be used as Cj sources in the synthesis of carbo- and heterocycles via cyclization or transfer reactions. 

E. O. Fischer and W. Schambeck, /. Organomet. Chem., 1980, 201, 311. Ketene-iminyl complexes of manganese and rhenium formed by addition of isocyanides to cationic carbyne complexes. 

E. O. Fischer and G. Besl, Z. Naturforsch., Teil B, 1980, 34, 1186. Novel carbene complexes of manganese obtained by reaction of cationic carbyne complexes with nucleophiles. 

Complexes Containing Metal-Carbon a-Bonds of the Groups Scandium to Manganese, Including Carbenes and Carbynes ... 

---