Komplexchemie reaktiver organischer verbindungen. XLVII. Synthese, strukturchemie und druckcarbonylierung von metallcarben-komplexen

The diazoalkane route has been used for the clean incorporation of diarylcarbene ligands into the organomanganese complexes of composition (η⁵-C₅H₄R)Mn(CO)_2- thf (1, R = H; 2, R = CH₃; thf = tetrahydrofuran), whose precursors are labile to substitution. The structure of the complex 4b derived from diazosuberon (3b) and exhibiting a seven-membered carbocyclic carbene ligand has been established by virtue of a single-crystal X-ray diffraction study (monoclinic, space group C_2h⁵-P2/n; a 1045.6(4), b 789.9(4), c 2153.6(4) pm; β 101.56(3)°; Z = 4; R = 0.075, R_w = 0.059). Using the same synthetic approach, the dinuclear compound 4d containing an ω,ω′-biscarbene bridge is accessible in 52% yield starting from 1,4-bis(diazobenzyl)benzene (3d). A methodologically simple procedure for the synthesis of η²-ketene complexes emerges from high-pressure carbonylation of the metal carbenes 4b and 5b. The geometry of the benzannelated cycloheptanylidenketene derivative 7b has also been elucidated by X-ray diffraction techniques (monoclinic, space group P2₁/n; a 998.9(3), b 1302.3(4), c 1466.6(4) pm; β 91.33(4)°; Z = 4; R = 0.057; R_w = 0.062).