Syntheses, crystal structures and magnetic behaviour of [Li(12-crown-4)2][Li(12-crown-4)OH2]2[Nb6Cl18], [Li(15-crown-5)2(OH2)]3[Nb6Cl18], and [(18-crown-6)2(O2H5)]3[Nb6Cl18]

The title compounds were prepared through reactions of Li2Nb6Cl16 With the corresponding crown ethers in acetone. All three compounds were obtained as dark brown crystals. Their structures were solved with the means of single-crystal X-ray diffraction. [Li(12-crown-4)(2)] [Li(12-crown-4)(OH2)](2) [Nb6Cl18]: space group P2(1)/n, Z=2, a=1320.4(1), b=1879.1(1), c=1321.7(1) pm, beta =92.515(6)degrees, R-1=0.0297 (I>2 sigma (I)). The crystal structure contains Li+ sandwiched by two 12-crown-4-ethers plus Li+ coordinated by one 12-crown-4-ether and one water molecule. [Li(15-Crown-5)(2)(OH2)](3)[Nb6Cl18]: space group R (3) over bar, Z=3, a=b=2081.7(1), c=1991.7(1) pm, R-1=0.0395 (I>2 sigma (I)). In the crystal structure Li+ and one water molecule are sandwiched by two 15-crown-5-ethers. [(18-crown-6)(2)(O2H5)](3) [Nb6Cl18]: space group P (1) over bar, Z=1, a=1405:1 (1), b=1461.1(2), c=1492.2(2) pm; alpha =98.80(1)degrees, beta =98.15(1)degrees, gamma =97.41(1)degrees, R-1=0.0538 (I>2 sigma (I)). H5O2+ was found in the structure refinement sandwiched between two 18-crown-6-ethers. All compounds reported contain [Nb6Cl18] clusters with Nb-Nb distances between 299 and 301 pm. The paramagnetic behaviour expected for [Nb6Cl18](3-) in all three compounds was confirmed by magnetic measurements.