Struktur des Cycloheptatrien‐molybdän‐tricarbonyls, C7H8Mo(CO)3

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Abstract
Crystals of cycloheptatriene‐molybdenum‐tricarbonyl, C7H8Mo(CO)3, are monoclinic, a = 13,42; b = 7,144; c = 12,28 Å; β = 122° 15′; Z = 4; space group P 21/a. The crystal structure has been determined and refined by difference syntheses and least squares analysis of partial three‐dimensional data to a reliability index R = 6,4%. A feature of the refinement is that in spite of the presence of the molybdenum atom, the hydrogen contributions to the electron density and to the structure factors are discernable. The molecule possesses an approximate symmetry plane passing through the Mo atom, the CH2 group of the ring, and one of the CO groups, the three carbonyls (MoC; 1,95 to 1,99 Å; CO; 1,13 to 1,18 Å) being situated on the opposite side of the metal atom to the ring. In the 7‐membered ring the pattern of single and double bonds is clearly established from the observed CC distances. There is no tendency towards formation of a norcaradiene‐like arrangement. The CH2 group deviates markedly (0,67 Å) from the mean plane of the other six atoms, which are only roughly equidistant (2,31 to 2,46 Å) from the metal atom.