Marti Niklaus, Spingler Bernhard, Breher Frank, Schibli Roger
Centre for Radiopharmaceutical Science, ETH-PSI-USZ, 5232 Villigen, Switzerland.
Inorg Chem. 2005 Aug 22;44(17):6082-91. doi: 10.1021/ic050442h.
The ligand substitution behavior of ReBr3(CO)32 (1) and [ReBr3(CO)2(NO)]NEt4 (2) in aqueous media was compared. Ligand exchange reactions were performed with multidentate chelating systems such as picolylaminediacetic acid (L1; N,N',O,O'), nitrilotriacetic acid (L2; N,O,O',O''), iminodiacetic acid (L3; N,O,O'), and bis(2-pyridyl)methane (L4; N,N'). The products of the substitution reactions were isolated and characterized by means of IR, NMR, MS, and X-ray structure analysis. NMR and crystallographic analyses confirmed the formation of single structural isomers in all cases with a ligand-to-metal ratio of 1:1. With ligands L1 and L2 and precursor 1 the tridentately coordinated complexes [Re(L1)(CO)3] (7) and [Re(L2)(CO)3]2- (8) were formed. With precursor 2 the same ligands unexpectedly coordinated tetradentately after displacing a CO ligand, yielding complexes [Re(L1)(CO)(NO)] (3) and [Re(L2)(CO)(NO)]- (4). In both complexes NO was found to be coordinated trans to the carboxylate group. Time-dependent IR spectra of the reaction of 2 with ligand L1 and L2 confirmed the loss of one CO during the reaction. The product of the reaction of 2 with L3 was identified as the neutral complex [Re(L3)(CO)2(NO)] (5), again, with the nitrosyl coordinated trans to the carboxylate. With 1, ligand L3 formed the anionic complex [Re(L3)(CO)3]- (9). Finally the reactions with L4 yielded the complexes [ReBr(L4)(CO)2(NO)]Br (6) and [ReBr(L4)(CO)3] (10), in which bromide was found to be coordinated trans to the NO and CO, respectively. The X-ray structures of 3, 5-7, and 10 are discussed: 3, monoclinic P2(1)/n, with a = 14.6071(6) A, b = 8.0573(3) A, c = 24.7210(11) A, beta = 107.117(5) degrees, and Z = 4; 5, triclinic P1, with a = 6.9091(5) A, b = 9.8828(7) A, c = 14.2834(10) A, alpha = 89.246(9) degrees, beta = 89.420(9) degrees, gamma = 86.196(9) degrees, and Z = 4; 6, triclinic P1, with a = 9.8236(8) A, b = 10.0949(8) A, c = 12.5346(10) A, alpha = 108.679(9) degrees, beta = 111.992(9) degrees, gamma = 95.426(10) degrees, and Z = 2; 10, monoclinic P2(1)/c, with a = 12.7491(12) A, b = 13.3015(13) A, c = 9.0112(9) A, beta = 107.195(2) degrees, and Z = 7.
比较了ReBr₃(CO)₃₂（1）和[ReBr₃(CO)₂(NO)]NEt₄（2）在水介质中的配体取代行为。使用多齿螯合体系如吡啶甲胺二乙酸（L1；N,N',O,O'）、次氮基三乙酸（L2；N,O,O',O''）、亚氨基二乙酸（L3；N,O,O'）和双(2 - 吡啶基)甲烷（L4；N,N'）进行配体交换反应。取代反应产物通过红外光谱（IR）、核磁共振（NMR）、质谱（MS）和X射线结构分析进行分离和表征。核磁共振和晶体学分析证实，在所有情况下均形成了配体与金属比例为1:1的单一结构异构体。对于配体L1和L2以及前体1，形成了三齿配位的配合物[Re(L1)(CO)₃]（7）和[Re(L2)(CO)₃]²⁻（8）。对于前体2，相同的配体在取代一个CO配体后意外地形成了四齿配位，生成配合物[Re(L1)(CO)(NO)]（3）和[Re(L2)(CO)(NO)]⁻（4）。在这两种配合物中，发现NO与羧酸根基团呈反式配位。2与配体L1和L2反应的时间分辨红外光谱证实了反应过程中一个CO的损失。2与L3反应的产物被鉴定为中性配合物[Re(L3)(CO)₂(NO)]（5），同样，亚硝酰基与羧酸根呈反式配位。对于1，配体L3形成了阴离子配合物[Re(L3)(CO)₃]⁻（9）。最后，与L4的反应生成了配合物[ReBr(L4)(CO)₂(NO)]Br（6）和[ReBr(L4)(CO)₃]（10），其中发现溴分别与NO和CO呈反式配位。讨论了3、5 - 7和10的X射线结构：3，单斜晶系P2(1)/n，a = 14.6071(6) Å，b = 8.0573(3) Å, c = 24.7210(11) Å，β = 107.117(5)°，Z = 4；5，三斜晶系P1，a = 6.9091(5) Å，b = 9.8828(7) Å，c = 14.2834(10) Å，α = 89.246(9)°，β = 89.420(9)°，γ = 86.196(9)°，Z = 4；6，三斜晶系P1，a = 9.8236(
