Crystal and molecular structures of (dibenzo-18-crown-6)(nitrato-O,O ')tetrahydrofuranpotassium, [K(DB18C6)(THF)(NO3)]

The (dibenzo-18-crown-6)(nitrato-O,O')tetrahydrofuranpotassium complex [K(D B18C6)(THF)(NO3)] (I) was synthesized and studied using X-ray diffraction a nalysis. The crystals are orthorhombic: a = 9.608 Angstrom, b = 9.926 Angst rom, c = 27.234 Angstrom, Z = 4, space group P2(1)2(1)2(1). The structure w as solved by the direct method and refined by the least-squares method in t he anisotropic approximation to R = 0.099 over all 2620 measured independen t reflections (CAD4 automated diffractometer, lambda MoKalpha radiation). C omplex I in the crystal exists as individual host-guest molecules, the K+ c ation (CN 9) being located in the DB18C6 macrocycle cavity and being coordi nated to its six oxygen atoms and to two oxygen atoms of the nitrato ligand on one side of the macrocycle and to the THF oxygen atoms on the other sid e. The DB18C6 molecule in I has a butterfly conformation with approximate C -2v symmetry.