Synthesis and characterization of trans-(pyH) [Mo(NCS)4py2] and trans-(py2H) [Mo(NCS)4PY2].: Crystal structure of trans-(py2H) [Mo(NCS)4py2]

(pyH)[Mo(NCS)(4)py(2)] (1) (py = pyridine) was prepared by refluxing of the mixture of KSCN and [MoCl(3)py(3)] in pyridine. After the recrystallization of 1 in pyridine, single crystals of trans-(py(2)H)[Mo(NCS)(4)py(2)] (2) were obtained. X-ray structure determination of 2 reveals trans slightly elongated (4 + 2) octahedral arrangement of two staggered conformated (85.9(4)degrees) N-bond pyridine molecules (Mo-N(py) = 2.191(6), 2.176(5) (A) over circle) and four isothiocyanato groups in square-planar orientation, bonded within the range 2.083(7)-2.106(7) (A) over circle to molybdenum atom in the anion. In the (py(2)H)(+) cation, pyridine molecules are held together by a strong hydrogen bond with contact distance N7(...)N8 = 2.708(12) (A) over circle (N8-H8'(...)N7 geometry: N8-H8'(...)N7 = 175(7)degrees, N7(...)H8' = 1.65(7) (A) over circle, N8-H8' = 1.06(7) (A) over circle). The angle between the best planes through the pyridine-cation rings is 70.7(6)degrees. The results of IR and UV/Vis spectroscopy indicate the same arrangement of the ligands in the compounds 1 and 2.