Crystal structure of a mixed-valence μ-oxide Sn12 cluster

The mixed-valence μ-oxide Sn12 cluster, decacarbonyltetra-μ4-oxido-hexa-μ3-oxido-tetrakis[μ-2,2′-(pyridine-2,6-diyl)bis(1,1-diphenylethanolato)]decatin(II)ditin(IV)dimolybdenum(O)(2 Mo—Sn) toluene heptasolvate, [Mo2Sn12(C33H27NO2)4O10(CO)10]·7C7H8, has a crystallographically imposed inversion centre. The asymmetric unit also contains three and a half toluene solvent molecules, one of which is disordered about a centre of symmetry. The complex molecule comprises six distinct Sn atom species with four different coordination numbers, namely 3, 4, 5, and 6. The SnII atoms forming the central Sn10O10 core adopt distorted trigonal–pyramidal, square-pyramidal and octahedral coordination geometries provided by the μ-oxide atoms and by the O- and N-donor atoms of two pyridinediethanolate ligands. The terminal SnIV atoms have distorted trigonal–bipyramidal coordination geometries, with a μ4-oxide atom and the N atom of a pyridinediethanolate ligand occupying the axial positions, and the Mo atom of a Mo(CO)5 group and the alkoxy O atoms of a ligand forming the equatorial plane. In the crystal, weak intra- and intermolecular C—H⋯O hydrogen bonds are observed.

The mixed-valence -oxide Sn 12 cluster, decacarbonyltetra-4 -oxido-hexa-3 -oxido-tetrakis[-2,2 0 -(pyridine-2,6-diyl)bis(1,1-diphenylethanolato)]decatin(II)ditin(IV)dimolybdenum(O)(2 Mo-Sn) toluene heptasolvate, [Mo 2 Sn 12 (C 33 H 27-NO 2 ) 4 O 10 (CO) 10 ]Á7C 7 H 8 , has a crystallographically imposed inversion centre. The asymmetric unit also contains three and a half toluene solvent molecules, one of which is disordered about a centre of symmetry. The complex molecule comprises six distinct Sn atom species with four different coordination numbers, namely 3, 4, 5, and 6. The Sn II atoms forming the central Sn 10 O 10 core adopt distorted trigonal-pyramidal, square-pyramidal and octahedral coordination geometries provided by the -oxide atoms and by the O-and N-donor atoms of two pyridinediethanolate ligands. The terminal Sn IV atoms have distorted trigonal-bipyramidal coordination geometries, with a 4 -oxide atom and the N atom of a pyridinediethanolate ligand occupying the axial positions, and the Mo atom of a Mo(CO) 5 group and the alkoxy O atoms of a ligand forming the equatorial plane. In the crystal, weak intraand intermolecular C-HÁ Á ÁO hydrogen bonds are observed.

S2. Experimental
The title compound was obtained in 10% yield by the reaction of equimolar mixture of [C 5 H 3 N(CH 2 CPh 2 O) 2 ] 2 Sn and Mo(CO) 5 *THF (generated at room temperature in THF in situ under UV irradiation of Mo(CO) 6 in THF) in toluene solution. The crystals suitable for X-Ray analysis were obtained after recrystallization from toluene at room temperature.

S3. Refinement
All non-hydrogen atoms were refined with anisotropic thermal parameters except for the toluene solvent molecules. The C141-C147 toluene molecule is disordered over two orientations about an inversion centre. The C(sp 2 )-C(sp 2 ) and C(sp 2 )-C(sp 3 ) bond distances of the C121-C127 and C131-C137 toluene molecules were constrained to be 1.400 (5) and 1.480 (5) Å, respectively, and isotropic displacement parameters set equal and refined as free variables were applied. All U iso (H) = 1.2 U eq (C) or 1.5 U eq (C) for methyl H atoms. A rotating model was applied to the methyl groups. Nine outliers were omitted in the last cycles of refinement.

Figure 1
The molecular structure of the title compound, with displacement ellipsoids shown at the 50% probability level. Toluene solvent molecules, hydrogen atoms and labels for carbon atoms are omitted for clarity. Suffix A indicates the symmetry operator 2-x, 2-y, -z. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.002 Δρ max = 1.05 e Å −3 Δρ min = −0.86 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (