The BPh4- salt of the carbyne complex [CP(CO)2Re=CTol]+, 1, undergoes net [2 + 2] cycloaddition of cis-azobenzene, cis-azotoluene, and benzo[c]cinnoline to give new complexes 5a, 5b, and 7, respectively, which possess four-membered metallacycles. The BCl4- salt of complex 1 initially reacts with cis-azobenzene and cis-azotoluene to give metallacycles 5a and 5b, but upon stirring these complexes abstract chloride from the BCl4- anion and insert a CO ligand into the Re-carbon bond of the metallacycle to give new complexes possessing five-membered metallacycles. With benzo[c]cinnoline, the BC14- salt of complex 1 reacts to give initially the metallacycle 7 formed from the BPh4-salt, but upon stirring, the benzo[c]cinnoline group is displaced by chloride (from BCl4-) to yield the chlorocarbene complex CP(CO)2Re=C-(CI)Tol. The metallacycles 5a and 5b react with [(Ph3P)2N]CI to give new complexes (10a,b) that result from loss of a CO ligand and an ''NPh'' group from the metallacycle, coordination of Cl-tothemetal, ortho-metalation of the N-aryl group, and hydrogen migration to the remaining nitrogen atom. The BC14- salt of complex 1 reacts with ethylene oxide, propylene oxide, and isobutylene oxide to form new carbene complexes of the form CP(CO)2Re=C(Tol)OCR2CR2Cl that result from chloride-induced ring opening and addition of the epoxide to the carbyne carbon. A similar ring-opening and addition of 3,3-dimethyloxetane occurs with the BC14- salt of complex 1 to form the new carbene complex CP(CO)2Re=C(Tol)OCH2CMe2CH2Cl (17). With 2-methylaziridine, carbyne complex 1 reacts to give an aziridinocarbene complex, and complex 1 abstracts sulfur from 2 equiv of propylene sulfide to give the eta2-dithiocarboxylate complex [Cp(CO)2Re{eta2-S2CTol}]BPh4(19). Carbyne complex 1 and its methylcarbyne analogue both react with benzophenone hydrazone to give the hydrazonyl carbene complexes Cp(CO)2Re=C(R)NHN--CPh2,20 (R = Tol) and 21 (R = Me). Complex 19 reacts with PMe3 to displace the Cp ligand as the phosphonium salt [CpPMe3]BPh4 and form the new complex trans-(CO)2(PMe3)2Re{eta2-S2CTol}. A similar reaction of PMe3 occurs with complex 7 to give initially a cis-bis(phosphine) complex 24 which isomerizes upon heating to a trans derivative 25. Complexes 5a and 5b react with PMe3 to give similar Cp displacement reactions and form trans-bis(phosphine) complexes 26a,b in which the metallacycles have undergone a rearrangement to form eta2-benzamidinato ligands. Complexes 10a, 17, 20, 21, 24, 25, and 26a have been crystallographically characterized.
