INFRARED, CONDUCTANCE, AND KINETIC EVIDENCE FOR ALKALI-METAL ION INTERACTIONS WITH DERIVATIVES OF MANGANESE CARBONYLATES
INFRARED, CONDUCTANCE, AND KINETIC EVIDENCE FOR ALKALI-METAL ION INTERACTIONS WITH DERIVATIVES OF MANGANESE CARBONYLATES
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DOI：
10.1021/ja00427a011
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发表时间：
1976-01-01
影响因子：
15
通讯作者：
DREW, DA
中科院分区：
文献类型：
--
作者：
DARENSBOURG, MY;DARENSBOURG, DJ;DREW, DA
红外光谱，动力学和电导率数据的组合已被用来定义的性质和重要性，在碱金属锰羰基化合物的离子配对现象。红外光谱分析表明，在-NaMn（CO）* L（L= PMe_2Ph，PPh_3，P（OPh）_3，和CO）中观察到的接触离子相互作用是Na ~+与赤道CO基团中的氧相互作用。电导滴定表明，在形成溶剂分离的离子对和M+ Mn（CO）s-的过程中，每个Na+或Li+中有2 ~ 4个HMPA分子和每个Na+或Li+中有1个15-冠-5-大环聚醚分子的特异性相互作用。这些络合阳离子的重要性体现在卤代烷与M+ Mn（CO）4L_（L= CO和P（OPh）3）在THF中反应的活化参数中。在阳离子配位剂HMPA存在下，RX生成m-RMn（CO）_4L的速率因活化负熵增大而大大降低。中心到中心的距离参数和解离常数的离子对来自电导对浓度的依赖性进行了讨论的阴离子和阳离子的溶剂化球的电子性质。本文还指出了与不对称负离子有关的一个特别有趣的距离参数，离子配对在碳负离子反应中的作用已引起有机化学家和物理化学家的极大注意。2 - 4对过渡金属有机阴离子的化学反应性的类似的离子配对效应还没有被很好地定义，尽管Ia和2a族金属离子与过渡金属羰基化物中的羰基氧相互作用的物理现象被很好地记录。已知[5-C5 H5 Mo（CO）3] 2 Mg（C5 H5 N）4的晶体结构包含平面py 4 Mg + 2，其中两个剩余的八面体位置被两个相邻的（5-C5 H5 MoCCO））-的一个羰基氧占据。5溶液中相互作用的鉴定主要是基于在r（CO）区或远红外区的红外光谱分析，在远红外区可以观察到阳离子-溶剂笼的振动运动。因此Edgell等证明纳科（CO）4是由溶剂分离和接触离子对（CO）3CoCO_-Na+在四氢呋喃中的平衡组成。6其他最近的相互作用溶液研究包括化合物，如LiMn（CO）5，7 NaMn（CO）5，7 NaRFe（CO）4，8和Li-[Ph 3 PFe（CO）3C（0）Ph]。9
A combination of ir, kinetic, and conductivity data has been used to define the nature and importance of ion-pairing phenomena in alkali metalmanganese carbonylates. Infrared analysis indicates the contact ion interactions observed for-NaMn (CO)* L (L= PMe2Ph, PPh3, P (OPh) 3, and CO) tobe that of Na+ interacting with the oxygen of an equatorial CO group. Conductometric titrations indicate specific interaction of two to four HMPA moleculesper Na+ or Li+ and one 15-crown-5-macrocyclic polyether per Na+ or Li+ in the formation of solvent-separatedion pairs and free ions of M+ Mn (CO) s-. The importanceof these complexed cations is manifest in the activation parameters for reactions of alkyl halides with M+ Mn (CO) 4L_ (L= CO and P (OPh) 3) in THF. In the presence of a cation-complexing agent such as HMPA, the rate of ad-dition of RX to form m-RMn (CO) 4L is drastically lowered as a result of a larger negative entropy of activation. Center-to-center distance parameters and dissociation constants for ion pairs as derived from conductance dependence on concentration are discussed in terms of the electronic nature of the anion and the solvation sphere of the cation. Aparticularly interesting ob-servation on distance parameters as related to asymmetric anions is noted.The role of ion pairing in reactions of carbanions has re-ceived an enormous amount of attention from organic and physical chemists. 2" 4 Similar ion-pairing effects on chemical reactivity of transition metal organic anions have not been well-defined although the physical phenomenon of group la and 2a metal ion interactions with the carbonyl oxygen in transition metal carbonylates is well documented. The crystal structure of [5-C5H5Mo (CO) 3] 2Mg (C5H5N) 4 is known to contain a planar py4Mg+ 2 with the two remaining octahedral sites occupied by one carbonyl oxygen of two adjacent^-CsHsMoCCO))-. 5 Identification of interaction in solution has been based principally on the analysis of infrared spectra either in the r (CO) region or in the far infrared where cat-ion-solvent cage rattling motions may be observed. Thus NaCo (CO) 4 was shown by Edgell et al. toconsist of an equilibrium of solvent separated and contact ion pairs,(CO) 3CoCO_—Na+, in tetrahydrofuran. 6 Other more recent solution studies of interactions include compoundssuch as LiMn (CO) 5, 7 NaMn (CO) 5, 7 NaRFe (CO) 4, 8 and Li-[Ph3PFe (C0) 3C (0) Ph]. 9