trans-(2,2′-Bipyrimidine)diiodido(isopropoxido)oxidorhenium(V)

In the title compound, [Re(C3H7O)I2O(C8H6N4)], the ReV atom adopts a distorted octahedral ReI2O2N2 geometry, with the O atoms in a trans conformation and the I atoms in a cis conformation. Two intramolecular C—H⋯I contacts occur. The crystal structure is stabilized by intermolecular C—H⋯O, C—H⋯N and C—H⋯I hydrogen bonds.

In the title compound, [Re(C 3 H 7 O)I 2 O(C 8 H 6 N 4 )], the Re V atom adopts a distorted octahedral ReI 2 O 2 N 2 geometry, with the O atoms in a trans conformation and the I atoms in a cis conformation. Two intramolecular C-HÁ Á ÁI contacts occur. The crystal structure is stabilized by intermolecular C-HÁ Á ÁO, C-HÁ Á ÁN and C-HÁ Á ÁI hydrogen bonds.
Financial support by the Polish Ministry of Science andHigher Education (grant No. N N204 016735, in years 2008-2010)
The O-Re-O unit is nearly linear with an angle of 169.69 (3)°. Moreover, a molecule of 2,2'-bipyrimidine is coordinated with Re-N bond length of Re1-N1 2.175 (5) %A, Re1-N2 2.183 (6) Å, which is comparable to the previously investigated trans-[ReCl 4 (py) 2 ] (Mrozinski et al., 2002, Herrman et al., 1990. Re atom lies within the plane of I1, I2, N1, N2 atoms, the N1-Re1-O1 and N2-Re1-O1 angles are 88.63 (19), 86.93 (14) and N1-Re1-O2, N2-Re1-O2 83.37 (14) and 84.87 (15) and are directed in side to 2,2'-bipyrimidine. The rings of the 4,4'-bpy ligand are coplanar with the plane defined by the I ligands, one of the Re-N bond is shorter (Re1-N1 2.175 (5) Å, Re1-N2 2.183 (6) Å), which may be a result of iodido ligand presence. The molecule conformation is stabilized by intramolecular hydrogen bonds C(1)-H(1)···I(1) and C(6)--H(6)···I(2), as well as by the intermolecular hydrogen bonds of C-H···O and C-H···N type. All hydrogen bonds are summarized in  Fig. 2. In the structure the stacking interactions are observed. pi-pi stacking interactions between the 2,2'-bypirymidine rings contribute to forming a supramolecular network structure (Fig. 2). The centroid-centroid distance of the adjacent aromatic rings is about 3.58%A, indicating a normal pi-pi interaction. The corresponding TG-DTA curves (the measurement was carried out under nitrogen atmosphere) for the title compound (Fig. 3) show a three-step decomposition process and that the compound is very stable during heating. In the first step of the thermal decomposition process weight loss in the temperature range 242-247°C of 1.39% (calc. 1.43%) is observed. In DTA curve, this decomposition is visible as an endothermic peak at temperature 247°C, indicating the presence of coordinated 4.4,-bipyrimidine (corresponding to the weight loss of 1.39% in thermal decomposition, which is in agreement with the calculated value of 1.43%). Further weight losses correspond to decomposition of further compound parts, they are continuous and are difficult for unambiguous interpretation (decomposition of all compound constituents except for rhenium part). Another peak at 800°C is also observed, however, it is difficult to interpret. It is possible, that the decomposition process leads to rhenium oxides. Similar decomposition process through many intermediate stages has been observed for (NH 4 ) 2 [Re 3 Cl 12 ] (Irmler et al., 1991). In conclusion, an interesting rhenium(V) trans-2,2,bipyrimidine-diiodido-oxido-(2-propoxido)-rhenium(V) complex with 2-propoxido ligand was obtained. The crystal structure is stabilized by hydrogen bonding interactions. This is the first structural report confirming the existence of a iodido rhenium complex with an aromatic amine and 2-propoxido ligand in coordination sphere.

Experimental
A mixture of (NH 4 ) 2 [ReI 6 ] (prepared according to the literature procedure (Watt & Thompson, 1963)  TG-DTA Thermogravimetric measurements were carried out using a TG-DTA SETSYS 16Y18 device under nitrogen atmosphere for a sample placed in Al 2 O 3 crucible. The investigated temperature range was from room temperature to 1400°C at 10°C / min. temperature changes rate. IR spectra The room temperature FT-IR spectra of polycrystalline samples were measured by means of the Bruker IFS-66 instrument.

Refinement
The H atoms were generated geometrically and refined using a riding model, with C-H = 0.95 Å and U iso (H) = 1.2 U eq (C).
The highest peak of 0.82 electrons at the difference Fourier map was situated near the Re atom.

trans-(2,2'-Bipyrimidine)diiodido(isopropoxido)oxidorhenium(V)
Crystal data 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 Rfactors(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