Novel Cyclizations Involving Cationic Carbyne Complexes

Novel Reactions of Cationic Carbyne Complexes of Manganese and Rhenium with (Ph3P)2NW(CO)5NCO, (Ph3P)2NW(CO)5SCN, and NaW(CO)5CN

“…However, the formation of 6 might involve initial formation of the - NCO anion arising from breakage of the - W(CO) 5 NCO anion; then, the - NCO anion attacks at the carbyne carbon of 1 with bonding of the N atom to the carbene carbon C(9) and the carbon atom C(8) to the cyclopentadienyl ring C(20) to form a chelated manganese carbene complex accompanied by migration of a hydrogen atom from the cyclopentadienyl ring to the N atom. Analogous results have been observed in the reactions of the cationic manganese carbyne complexes [Cp(CO) 2 Mn⋮CR] + (R = Ph, Tol) with imines Ph(H)CNR‘ (R‘ = Me, −N(H)Ph), which give the chelated carbene complexes [η-C 5 H 4 (CO) 2 MnC(R)N(R‘)C(H)Ph], in which the imine carbon has been coupled to the cyclopentadienyl ligand. , Similar metallacyclic carbene complexes [η-C 5 H 4 (CO) 2 MnC(NR 2 )NCPh] (R = Me, Et, i-Pr, i-Bu) have also been obtained , in the reaction between the cationic manganese carbyne complex [Cp(CO) 2 Mn⋮CPh] + and dialkylcyanamides N⋮CNR 2 .…”

Mixed Dinitrogen−Organocyanamide Complexes of Molybdenum(0) and Their Protic Conversion into Hydrazide and Amidoazavinylidene Derivatives

“…Cyanamides, N⋮CNR 2 (R = H, alkyl or aryl), can be regarded as amino-functionalized nitriles, but despite the well developed coordination chemistry of organonitriles , and of the biological and synthetic interest of such species [in particular cyanamide itself, N⋮CNH 2 , and its dimeric form, cyanoguanidine, NCNC(NH 2 ) 2 ], − only scarce examples of reactions of cyanamide ligands have been reported, and the study of their activation by coordination to a transition metal center still remains virtually unexplored, as well as the effect of the amino moiety on the reactivity of the cyano group. Insertion into a metal−carbon multiple bond, − metathesis with a metal−metal triple bond, nucleophilic addition of an oxime or of an alcohol (in this case to cyanoguanidine) to form a five- or six-membered azametallacycle, respectively, and dehydrogenation of NCNH 2 followed by electrophilic addition , or deprotonation or deamination (of cyanoguanidine) are the most significant reactions reported so far.…”

Azametallacycles from Ag(I)- or Cu(II)-Promoted Coupling Reactions of Dialkylcyanamides with Oximes at Pt(II)

“…These reactions contrast with the usual unreactivity of ligating diorganocyanamides, e.g., NCNR 2 (R = Me or Et) at the Pt(II) and Fe(II) complexes we have previously prepared. Moreover, only scarce examples of reactions of diorganocyanamides with transition metal complexes (apart from conventional coordination) have been quoted, and they involve, e.g., their insertion into metal−carbon double − or triple bonds and metathesis like reactions with a metal−metal triple bond to give alkylidyne and nitride complexes.…”