TRIAQUAHEXATHIOCYANATOBISMUTHLANTHANUM DIHYDRATE, [BI(SCN)(6)LA(H2O)(3)]CENTER-DOT-2H(2)O, AND TRIAQUAHEXATHIOCYANATOBISMUTHNEODYMIUM DIHYDRATE, [BI(SCN)(6)ND(H2O)(3)]CENTER-DOT-2H(2)O

In the crystal state, the title compounds form dihydrated three-dimens ional polymeric complexes of general formula [Bi(SCN)(6)Ln(H2O)(3)].2H (2)O, isomorphic with and with a similar structure to the LaFe(CN)(6). 5H(2)O structure type. The distorted octahedral BiS6 polyhedra and LnN (6)O(3) polyhedra are connected by the bridging thiocyanate groups in the three-dimensional network. Six N atoms form trigonal prisms around the Ln(III) ions with the three rectangular faces capped by three H2O molecules. This gives La and Nd coordination polyhedra in the form of tricapped trigonal prisms. The different structural roles of the wate r molecules explains the literature data regarding a two-stage dehydra tion of the crystals. A comparison of the bond lengths in the two stru ctures is given.