Undeca-carbonyl-1κC,2κC,3κC-(triethyl phosphite-1κP)-triangulo-triruthenium(0).

In the title triangulo-triruthenium compound, [Ru(3)(C(6)H(15)O(3)P)(CO)(11)], each Ru atom has distorted octa-hedral coord-ination geometry. The monodentate phosphine ligand is equatorially coordinated to one Ru atom, leaving one equatorial and two axial carbonyl substituents on the Ru atom. Each of the remaining two Ru atoms carries two equatorial and two axial carbonyl groups. In the crystal, mol-ecules are linked into an inversion dimer by a pair of inter-molecular C-H⋯O hydrogen bonds and the dimers are stacked along the b axis.

In the title triangulo-triruthenium compound, [Ru 3 (C 6 H 15 -O 3 P)(CO) 11 ], each Ru atom has distorted octahedral coordination geometry. The monodentate phosphine ligand is equatorially coordinated to one Ru atom, leaving one equatorial and two axial carbonyl substituents on the Ru atom. Each of the remaining two Ru atoms carries two equatorial and two axial carbonyl groups. In the crystal, molecules are linked into an inversion dimer by a pair of intermolecular C-HÁ Á ÁO hydrogen bonds and the dimers are stacked along the b axis.
In the title compound, the monodantate phosphine ligand has replaced a carbonyl group in the equatorial plane of the Ru 3 triangle. The triangulo-triruthenium is bonded equatorially to a monodentate phosphine ligand. The Ru2-Ru3 bond is noticeably longer [2.8605 (2) Å] compared to the other two Ru-Ru bonds [2.8348 (2) and 2.8436 (2) Å]. The unusual increase in the length of Ru-Ru bond in comparison with those of Ru 3 (CO) 12 structure (Churchill et al., 1977) can be attributed to the steric effect induced by the bulky substituent.
As observed in Ru 3 (CO) 12 , the bond from metal atoms to the axial CO groups in complex (I) are longer (Ru-C ave = 1.941 Å) compared to the equatorial CO groups (Ru-C ave = 1.917 Å). The equatorial Ru-C-O moieties are linear (average angle: 178.30°) whereas the axial Ru-C-O moieties are slightly bent (average angle: 174.14°). Similar observations were made by Bruce and co-workers for the range of monosubstituted complexes synthesized by them (Bruce et al., 1988).
In the crystal structure, the molecules are linked into dimers by intermolecular C12-H12A···O2 hydrogen bonds and stacked down the b axis ( Fig. 2 and Table 1).

Experimental
All the manipulations were performed under a dry oxygen-free nitrogen atmosphere using standard Shlenk technique. THF was dried over sodium wire and freshly distilled from sodium benzophenone ketyl solution. Radical anion method was used for the synthesis of complex (Bruce et al., 1987). The title compound (I) was prepared by mixing Ru 3 (CO) 12 (Aldrich) and P(O-CH 2 CH 3 ) 3 (BDH Chemicals Ltd. Poole England) in a 1:1 molar ratio in THF at 313 K. Separation of the product in pure form was done by column chromatography (Florisil, 100-200 mesh, eluant, dicholomethane: hexane). IR (cyclohexane): γ (CO) 2100, 2045, 2031 and 2015 cm -1 . Crystals suitable for X-ray diffraction were grown from dichlomethane/methanol solution at 283 K.