CATION-ANION INTERACTION IN THE [NA-KRYPTOFIX-221][W(CO)5O2CH] DERIVATIVE AND ITS RELEVANCE IN CARBON-DIOXIDE REDUCTION PROCESSES
CATION-ANION INTERACTION IN THE [NA-KRYPTOFIX-221][W(CO)5O2CH] DERIVATIVE AND ITS RELEVANCE IN CARBON-DIOXIDE REDUCTION PROCESSES
复制标题
DOI：
10.1021/ja00306a014
复制
发表时间：
1985-01-01
影响因子：
15
通讯作者：
PALA, M
中科院分区：
文献类型：
--
作者：
DARENSBOURG, DJ;PALA, M
[Na-kryptofix-221][W（C0）502CH]的结构已由X射线晶体学确定，并显示出甲酸酯配体的非配位氧与穴醚包封的钠阳离子之间的新型强接触离子配对。晶体属三斜晶系，空间群为P1，晶胞参数a = 10.221（2）λ，B = 10.845（2）λ，c = 12.779（2）λ，a = 87.93（1），λ = 89.47（1），y = 82.99（1）.最重要的结构方面是甲酸根的远端氧原子和钠之间的距离（2.388（9）π）是阳离子配位层中最短的Na-O键距离。虽然这种离子配对持续未络合的钠阳离子在四氢呋喃溶液中，穴状配体封装的物种存在作为溶剂分离或自由离子对在溶液中。对于五羰基乙酸钨阴离子衍生物，观察到类似的溶液行为。此外，在18-冠-6络合的Na+存在下，CH3CO2W（CO）5-阴离子显示出与在未络合的Na+阳离子存在下的阴离子的溶液结构近似的溶液结构。与这些溶液结构一致，在Na+或Na（18-冠-6）+的存在下，二氧化碳与CH3W（CO）5-反应以提供CH3CO2W（CO）5-的速率比用非相互作用的PPN+（双（三苯基膦）亚胺鎓阳离子）或Na-kryptofix-221 - 1-进行的速率提高了10倍。这些速率加速归因于在二氧化碳插入过程期间初始羧酸盐的阳离子稳定。
Thestructure of [Na-kryptofix-221][W (C0) 502CH] has been determined by X-ray crystallography and shown to exhibit a novel strong contact ion pairing between the uncoordinated oxygen of the formate ligandwith the cryptand-encapsulated sodium cation. The compound crystallizes in the triclinic space group P\with cell dimensions a= 10.221 (2) Á, b= 10.845 (2) Á, c= 12.779 (2) A, a= 87.93 (1), ß= 89.47 (1), and y= 82.99 (1). The most significant structural aspect is that the distance between the formate’s distal oxygen atom and sodium (2.388 (9) Á) is the shortest Na-O bond distance in the cation’s coordination sphere. Although this ion pairing persists for uncomplexed sodium cations in tetrahydrofuran solution, the cryptand-encapsulated species exists as a solvent-separated or free-ion pair in solution. Similar solutionbehavior is observed for the acetatotungsten pentacarbonyl anionic derivative. In addition, the CH3C02W (C0) 5" anion, in the presence of 18-crown-6 complexed Na+, displays a solution structure approximating that of the anion in the existence of the uncomplexed Na+ cation. Consistent with these solution structures, the rate of reaction of carbon dioxide with CH3W (CO) 5" to provide CH3C02W (C0) 5" is enhanced by a factor of 10 in the presence of Na+ or Na (18-crown-6)+ over that carried out with the non-interacting PPN+(bis (triphenylphosphine) iminium cation) or Na-kryptofix-221" 1". These rate accelerations are attributed to a cation stabilization of the incipient carboxylate during the carbon dioxide insertion process.