1,1,2,2,2,3,3,3-Octacarbonyl-1,1,2,3-tetrakis(1,3,5-triaza-7-phosphatricyclo[3.3.1.13,7]decane-κP)-triangulo-triosmium(0)

The title molecule consists of a triangular triosmium(0) core surrounded by eight carbonyl ligands and four 1,3,5-triaza-7-phosphatricyclo[3.3.1.13,7]decane ligands.


data reports
ligands. Previous efforts to produce triangular triosmium carbonyl compounds with more than three phosphane ligands have typically resulted in cluster fragmentation (Alex et al., 1987).
In the title compound, the four phosphane ligands adopt positions that maximize the distance between them (Fig. 1). Two PTA ligands coordinate to Os1 through their P atoms, and the other two PTA ligands coordinate one each to Os2 and Os3 through their P atoms. All PTA ligands are located in equatorial coordination sites so that the four phosphorus atoms are within 1 Å of residing in the same plane as the three osmium atoms. Two carbonyl ligands occupy equatorial sites (one each on Os2 and Os3), while the other six CO ligands occupy axial sites (two per Os atom). Each Os atom exhibits a pseudo-octahedral coordination environment, but the three coordination spheres are twisted relative to one another so that the axial CO ligands are no longer perpendicular to the Os3 plane as they are in Os 3 (CO) 12 (Corey & Dahl, 1962). The average C ax -Os-Os-C ax torsion angle is 29 (3) . Crystal structures have been reported for five Ru 3 (CO) 12-x L x complexes: one [L = P(OMe) 2 Ph] with two bridging CO ligands (Bruce et al., 1985), two [L = P(OEt) 3 , PMe 2 Ph] with two semi-bridging CO ligands, and two [L = P(OMe) 3 , P(OPh) 3 ] with only terminal CO ligands (Bruce et al., 1989). In all cases, the phosphane or phosphite ligands adopt the same coordination geometry as in the title complex. The average C ax -Ru-Ru-C ax torsion angles in the latter two are similar to that in the title complex with 35 (3) for L = P(OMe) 3 and 30 (2) for L = P(OPh) 3 . Such torsional twisting was also noted in the cases of Ru 3 (CO) 9 (PTA) 3 and Os 3 (CO) 9 (PTA) 3 , albeit to a significantly lower degree with average C ax -M-M-C ax torsion angles of 19 (2) and 17 (2) , respectively (Mager et al., 2015;Dugan et al., 2016). The average Os-Os bond length of 2.903 (22) Å in the title complex is virtually the same as that of 2.90 (2) Å in Os 3 (CO) 9 (PTA) 3 , suggesting that torsional distortion is preferred over metal-metal bond lengthening.
In the structure of the title complex, the molecules are stacked parallel to the a axis of the unit cell with every other Os 3 triangle facing in the opposite direction and tilted at an angle of 9 (1) from the previous Os 3 triangle in the same stack (Fig. 2). The planes defined by the Os 3 units appear to be roughly perpendicular to the b axis, but actually form 21 (1) angles with the ac plane. There is a slight disorder in the title View of the title molecule showing the atom-labeling scheme. Displacement ellipsoids are scaled to the 50% probability level. The Os 3 core is represented by the major disorder component. For the sake of clarity, the atoms labels for C15 (in front of N7) and C22 (behind N11) are omitted.

Figure 2
Packing of the molecules viewed approximately along the a axis.

Synthesis and crystallization
Dodcecacarbonyltriosmium (63.3 mg, 0.0698 mmol), PTA (87.6 mg, 0.557 mmol), 1,2-dichlorobenzene (6 ml), and acetonitrile (2 ml) were added to a 35 ml glass reaction vessel, then sealed with a PTFE cap and placed in a CEM Discover-SP microwave reactor. The mixture was stirred and heated at 458 K for 24 min to produce a vibrant orange solution. The solvent was removed and water (15 ml) was added to dissolve the residue. The resulting solution was filtered through a glass frit and the orange filtrate collected. After 16 h, a precipitate had formed. Filtering again allowed for the isolation of the title complex as an orange solid. IR (CO cm À1 in CHCl 3 ): 2033(w), 1970(sh), 1953(vs), 1921(m). Crystals grew as thin, reddish orange plates via diffusion of n-hexane into a CH 2 Cl 2 solution.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1. Three rather large electron density peaks located near the Os atoms persisted in the difference electron-density map after all of the expected atoms were included in the model. The position of these peaks suggested there was a slight disorder in the complex resulting from an approximately 60 rotation about an axis perpendicular to the plane through the three Os atoms. A disorder model with this in mind was proposed where these three electron-density peaks represented the alternate orientation of the Os 3 core. The variable x was assigned to the site occupancy for Os1, Os2 and Os3, while the site occupancy for Os1A, Os2A and Os3A was set to (1 À x). The displacement parameters for the lower occupancy Os atoms were set to be equal to those of the major component. The variable x refined to 0.9783 (4). Disorder of the associated CO and PTA ligands could not be resolved.

data-2
IUCrData (2020). 5, x200935 Refinement. Three rather large peaks persisted in the difference electron density map after all the expected atoms were included in the model. These peaks, all greater than 4 e-/A 3 , were located near the Os atoms. The position of these peaks suggested there was a slight disorder in the complex. The disorder resulted from an approximately 60 degree rotation about an axis perpendicular to the plane through the three Os atoms. A disorder model with this in mind was proposed where these three peaks represented the alternate orientation of the Os atoms. The variable x was assigned to the site occupancy for Os1, Os2 and Os3, while the site occupancy factors for Os1a, Os2a and Os3a was set to (1-x). The displacement parameters for the lower occupancy Os atoms was set to be equal to that of the major component. The variable x refined to 0.9783 (4). The other atoms of the alternate component were not included in the disorder model because the very low electron density of a 2% component would be lost in the noise.