Structural analysis of nine-coordinate lanthanide complexes: Steric control of the metal-water distance across the series
Structural analysis of nine-coordinate lanthanide complexes: Steric control of the metal-water distance across the series
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DOI：
10.1021/ic030203z
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发表时间：
2003-12-29
影响因子：
4.6
通讯作者：
Senanayake, K
中科院分区：
文献类型：
--
作者：
Parker, D;Puschmann, H;Senanayake, K
用单晶X-射线衍射法研究了手性DOTA四酰胺配体(L-1)[LnL(1)(H2O)](CF3-SO3)(3)·3H(2)O的10个类晶稀土(Ln)配合物的结构。Ln配位是一个O_4N_4正方形反棱镜，其O-4碱基被水配体覆盖。后者的空间要求位置导致沿Pr到Lu系列的Ln-OH2距离延长0.06埃(考虑到稀土元素的收缩)。同时，结合水氧与二球水氧之间的距离从3.17埃(Pr)减小到3.04埃(Lu)，这与配位水氧跨系列氢键受体能力的增强是一致的。剑桥结构数据库对[Ln(H2O)(9)](CF3-SO3)(3)盐(空间群P6(3)/m)和六个已报道的DOTA[L-2]等结构络合物的调查显示了类似的趋势。讨论了由此产生的基态结构失稳对水交换过程的影响。
The structures of 10 isomorphous lanthanide (Ln) complexes of a chiral DOTA tetra-amide ligand (L-1), [LnL(1)(H2O)](CF3-SO3)(3).3H(2)O, crystallizing in space group P2(1), have been studied by single-crystal X-ray diffraction. The Ln coordination is a O4N4 square antiprism, the O-4 base of which is capped by an aqua ligand. The sterically demanding position of the latter results in the lengthening of the Ln-OH2 distance along the Pr to Lu series by 0.06 Angstrom (after allowing for the lanthanide contraction). In parallel, the distance between the bound water oxygen and the second-sphere water oxygen is reduced from 3.17 Angstrom (Pr) to 3.04 Angstrom (Lu), consistent with the enhanced hydrogen bond acceptor ability of the coordinated water oxygen across the series. A Cambridge Structural Database survey of [Ln(H2O)(9)](CF3-SO3)(3) salts (space group P6(3)/m) and of six reported isostructural complexes of DOTA [L-2] revealed a similar trend. The implications of the resultant destabilization of the ground state structure for the water interchange process are discussed.