trans-Acetyldicarbonyl(η5-cyclopentadienyl)[tris(furan-2-yl)phosphane-κP]molybdenum(II)

The title compound, [Mo(C5H5)(C2H3O)(C12H9O3P)(CO)2], was prepared by reaction of [Mo(C5H5)(CO)3(CH3)] with tris(furan-2-yl)phosphane. The MoII atom exhibits a four-legged piano-stool coordination geometry with the acetyl and phosphine ligands trans to each other. The O atom of the acetyl ligand points down, away from the Cp ring. In the crystal, molecules form centrosymmetrical dimers via π–π interactions between furyl rings [the centroid–centroid distance is 3.396 (4) Å]. The dimers are linked by C—H⋯O hydrogen bonds into layers parallel to (100).

There are several particularly short intermolecular distances involving H atoms. One short contact (2.38 Å) is present between O1 of the acetyl carbonyl on one Mo complex and H8 of a Cp ring on another (Table 2). Another short contact (2.40 Å) involves O1 of the acetyl group of one Mo complex and H11 of a furyl group on another (Table 2). These contacts between the acetyl carbonyl and hydrogen atoms may contribute to the unusual geometry adopted by the acetyl ligand, where the carbonyl points down, away from the Cp ring. In related structures reported by this laboratory (Whited et al., 2012) and others (Churchill & Fennessey, 1968;Michelini-Rodriguez et al., 1993;Adams et al., 1997Adams et al., , 2000, the carbonyl points up toward the Cp ring. These hydrogen-bonding interactions lead to the formation of layers parallel to (100), as shown in Fig. 4.

CpMo(CO) 3 (CH 3 )
. This compound was prepared by a modification of the method used by Gladysz et al. (1979), as previously reported by Whited et al. (2012).
Crystalline material was obtained as yellow-orange prisms by vapor diffusion of pentane into a concentrated solution of I in diethyl ether at 233 K.

Refinement
H-atoms were treated in calculated positions and refined in the riding model approximation with distances of C-H = 0.95, 1.00 and 0.98 Å for the furanyl, cyclopentadienyl and methyl groups, respectively, and with U iso (H) = k×U eq (C), k = 1.2 for furanyl and cyclopentadienyl groups and 1.5 for methyl groups. Methyl group H atoms were allowed to rotate in order to find the best rotameric conformation. The maximum and minimum electron densities in the final difference Fourier map are located 0.98 and 0.77 Å, respectively, from atom Mo1.
Eight low-angle reflections were rejected from the high-quality data set due to the arrangement of the instrument with a conservatively sized beam stop and a fixed-position detector. The large number of reflections in this data set (and the Fourier-transform relationship of intensities to atoms) ensures that no particular bias was thereby introduced into this routine structure determination.

Figure 3
The centrosymmetrical dimers of I.