Bond lengths nitrate complexes

The coordination modes of the nitrate ligand in the complexes [TpBut]M(N03) (M = Cu, Ni, Co, Zn) are summarized in Fig. 46. (171, 184). Evidently, the coordination mode varies from unidentate for Zn to symmetric bidentate for Ni and Cu, with the cobalt derivative exhibiting an anisobidentate coordination mode. Moreover, the related cadmium derivative [TpBut,Me]Cd(N03) also exhibits bidentate coordination of the nitrate ligand, with Cd-0 bond lengths of2.272(6) A and 2.295(7) A (91). Such symmetric bidentate coordination contrasts with the significantly different Zn-0 interactions [1.978(3) A and 2.581(3) A] in unidentate [TpBut]Zn(N03). The coordination modes for a variety of [TpRR ]M(N03) complexes are summarized in Table VIII. 

Complexation of lanthanides in dimethyl sulfoxide with nitrate ion studied with Er(III) and Y(III) showed [98] coordination of 1.5 nitrate groups to the metal ion and 6 DMSO molecules. The nitrate is probably in a bidentate disposition with M-O(l) bond length of 2.38 A and M-0(2) length of 2.57 A. The overall coordination number for Er(III) is close to 9, similar to the solid complex of the composition Er(N03)3 -6DMS0. 

The crystal structure of (NH4)Ce(N03)6 shows monoclinic symmetry with each Ce(IV) atom coordinated by six bidentate nitrate groups and the symmetry around the cerium atom approximating closely to Th. The bond lengths and bond angles for Ce(IV) and Ce(III) nitrato complexes are given in Table 4.14 for comparison. 

The nitrate complexes Tb(N03)3(bipy)2, Ln(bipy)2(N03)3-H20 (Ln = Dy, Ho) have been synthesized and characterized. The anhydrous complexes have coordinated nitrate groups suggesting a coordination number of ten for Ln(bipy)2(N03)3. The molecular geometry is that of a bicapped triangularly faced dodecahedron [237] of D2 symmetry with Ln-O bond length of 2.605 A and two Ln-N bond lengths of 2.665 and 2.648 A. 

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