The organolithium dimer [Li2C(Ph2PNSiMe3)2]2 ([Li2-1]2) reacts with 2 equiv of [PtCl2(cod)] (cod = 1,5-cyclooctadiene) in Et2O solution to give the novel Pt−carbene complex [(η4-cod)Pt{C(Ph2PNSiMe3)2-κC,κN}] (2), which is characterized by a relatively long Pt−C(carbene) bond and relatively short Pt−C(olefin) interactions indicative of an electron-rich Pt center. Under oxygen- and moisture-free conditions, 2 is remarkably inert; the cod ligand is not displaced by either monodentate or bidentate phosphines, phosphine sulfide, phosphite, or pyridine at room temperature, nor is the four-membered C,N-chelate ring opened by these reagents. However, 2 reacts with the electrophiles MeOTf (OTf = trifluoromethanesulfonate) and CO2. In the former case, the uncoordinated N atom of 2 is methylated to form [(η4-cod)Pt{C(Ph2PNSiMe3)(Ph2PN(Me)SiMe3-κC,κN}][OTf] (3). In the latter, initial nucleophilic attack by the uncoordinated N atom on CO2, followed by trimethylsilyl group migration from N to O, gives [(η4-cod)Pt{C(Ph2PNSiMe3)(Ph2PNC(O)OSiMe3-κC,κN}] (4). Heating a benzene solution of 2 to 100 °C in a sealed tube for several hours, or to 60 °C for 10 min in the presence of H2O, yields the ortho-metalated complex [(η4-cod)Pt{CH(Ph(C6H4)PNSiMe3)(Ph2PNSiMe3)-κC,κC ‘}] (5), which is characterized by Pt−C distances that are in the typical range for Pt−C(alkyl) and Pt−C(arene) interactions. The diastereoselectivity of the ortho metalation is consistent with an oxidative addition (nucleophilic) reaction mechanism for the ortho metalation. In contrast to 2, 5 displays typical cod substitution reactivity with chelating phosphines. The reaction between [Li2-1]2 and [PtCl2(cod)] in C6H6 solution proceeds only very slowly and gives [Li][Pt{CH(Ph(C6H4)PNSiMe3)(Ph2PNSiMe3)-κC,κC ‘}{CH(Ph2PNSiMe3)2-κC,κN}] (7) in low yield.

Carbon monoxide replaces cod in the mono carbene phosphane imine complex 1 (see picture) to form, through a double silyl migration reaction, the remarkable complex 2 containing three carbene centers bound to platinum (cod=cycloocta‐1,5‐diene).

Stoichiometric reaction of [ Sm(Tp(Me2))2 ], 1, with a variety of reducible ketone- and quinone-type substrates gave thermally stable, isolable radical anions/ketyls in moderate to good yields. Thus reaction with benzophenone gave [Sm(Tp(Me2))2(OCPh2)], 2, with fluorenone [Sm(Tp(Me2))2(eta1-OC13H8)], 3, and di-tert-butylparaquinone [Sm(Tp(Me2))2(eta1-OC6H2(tBu)2O)], 4, each of which was structurally characterized. In the case of the less-hindered benzoquinone, an unimetallic semiquinone [Sm(Tp(Me2))2(OC6H4O)], 5, could be isolated, although it was unstable with respect to formation of the dimetallic complex [Sm(Tp(Me2))2]2(mu-OC6H4O), 6. Compound 6 was structurally characterized, as was its anthraquinone analogue [Sm(Tp(Me2))2]2(mu-OC14H8O), 7. When the analogous reaction was carried out between the less-reducing [Eu(Tp(Me2))2] and benzoquinone, only the europium analogue of the semiquinone 5, [Eu(Tp(Me2))2(OC6H4O)], 8, could be isolated. The use of the sterically hindered 3,5-di-tert-butyl-o-benzoquinone allowed isolation of [Sm(Tp(Me2))2(DTBSQ)], 9.