Metathetical Exchange, Synthesis, and Carbon Dioxide Addition of Higher Homologues of Group 9 Metal Carbynes

A one-pot synthesis for previously unknown heavy homologues of Group 9 metal carbynes [(Me₃P)₃Co≡GeAr*] (1), [(Me₃P)₃Rh≡GeAr*] (2), [(Me₃P)₃Ir≡GeAr*] (3), [(Me₃P)₃Ir≡SnAr*] (5), and [(Et₃P)₃Ir≡PbAr*] (7) is presented [Ar* = C₆H₃-2,6-(Trip)₂, Trip = 2,4,6-C₆H₂iPr₃]. During these preparations, the tetrylidynes [(Me₃P)₃Rh≡SnAr*] (4), and [(Me₃P)₃Rh≡PbAr*] (6), were also prepared in a one-pot procedure. In a hitherto unknown metathetical exchange reaction, the transition metal plumbylidynes were converted into the respective stannylidynes in reaction with terphenyl stannylene chloride, and the germylidynes were formed from the corresponding stannylidynes in reaction with terphenyl germylene chloride. These metathesis reactions were tracked by ³¹P{¹H} NMR spectroscopy, which shows complete exchange of the tetrel [EAr]-fragment and the formation of an intermediate in the rhodium plumbylidyne reaction with stannylene chloride (Ar = Ar*, Tbb). Reactions of the tetrylidynes (2-5) with carbon dioxide yield the products of a redox reaction [(Me₃P)₃(CO)M-E(η²-O₂CO-κ²O)Ar*] [E = Ge, M = Rh (11); M = Ir (12); E = Sn, M = Rh (14), M = Ir (16)] with a carbon monoxide coordinated at the transition metal and a carbonate coordinated at the Group 14 element. For tin the intermediates formed by mono CO₂ addition [(Me₃P)₃M(μ,η²-CO₂-κC:κO)SnAr*] [M = Rh (13), M = Ir (15)] have been isolated.