Metal–carbonyl and metal–nitrosyl complexes. Part XIII. X-Ray study of the molecular structures of π-cyclopentadienyl- and π-(methylcyclopentadienyl)-trans-iododicarbonyl(trimethyl phosphite) molybdenum

The molecular geometries of π-cyclopentadienyl- and π-(methylcyclopentadienyl)-trans-iododicarbonyl(trimethyl phosphite) molybdenum [(I) and (II)] have been determined by X-ray crystal-structure analysis. The Mo-P distances [2·406(9) and 2·388(8)A] are significantly shorter than in π-cyclopentadienyl-trans-iododicarbonyl(triphenylphosphine)molybdenum (III)[2·481(5)A], whereas the Mo-l distances [2·836(4) and 2·850(3)A in (I) and (II); 2·858(3)A in (III)] are essentially constant. Both (I) and (II) crystallize in the orthorhombic space group p212121, with Z= 4 in unit cells of dimensions : (I), a= 10·75, b= 16·60, c= 8·57 (all ± 0·01)A; (II), a= 16·317(6), b= 11·323(3), c= 8·740(2)A. Photographic data were used for (I) and diffractometer data for (II). The structures were solved by Patterson and Fourier methods and refined by least squares to R 7·8%[(I), 906 reflections] and 5·9%[(II), 1847 reflections].