MIXED-VALENCE INTERACTIONS IN DI-MU-OXO BRIDGED MANGANESE COMPLEXES
MIXED-VALENCE INTERACTIONS IN DI-MU-OXO BRIDGED MANGANESE COMPLEXES
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DOI：
10.1021/ja00462a025
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发表时间：
1977-01-01
影响因子：
15
通讯作者：
CALVIN, M
中科院分区：
文献类型：
--
作者：
COOPER, SR;CALVIN, M
研究了配合物[（L）_2Mn_0_2Mn（L）_2]_3 ~+（其中L= 2，2 ′-联吡啶或1，10-菲咯啉）以及相应的菲咯啉配合物（Ⅳ，Ⅳ）。L= 2，2 '-联吡啶的混合价（III，IV）配合物的晶体结构表明，由于锰离子的键长差别很大，该配合物具有深陷阱价态，相当于Robin和Day分类中的II类。我们已经研究了（III，IV）配合物的电子光谱，并观察到宽频带在近红外线，我们已分配到混合价带预期的II类系统。邻菲咯啉（Ⅳ，Ⅳ）络合物没有可比较的谱带。降低pH值的（III，IV）二聚体溶液可逆地裂解的反铁磁耦合（III，IV）二聚体的溶液磁化率的增加所确定的;损失的近红外波段发生二聚体裂解，虽然可见光谱的其余部分基本上是不变的。吸光度和溶液磁化率随pH的变化都是可逆的。近红外波段的溶剂依赖性很小，但与Hush理论的预测相反。然而，带宽与根据Hush的处理所预测的那些很好地一致（例如，预测的0.53 gm ~ 1，观察到的0.46 gm ~ 1）。联吡啶（III，IV）二聚体红外光谱中688 cm-1处的一个谱带被同位素取代180而发生位移，并归属于桥的一种伸缩模;邻菲咯啉（III，IV）和-（IV，IV）配合物也有类似的谱带。1972年，Plaksin等人1报道了高氯酸二-^-氧代-四（2，2 '-联吡啶）二锰（III，IV）（以下称为联吡啶（III，IV）二聚体）的晶体结构，它最初是由Nyholm和Turco于1960年合成的。这种复杂的，尼霍姆和图尔科曾制定为一个
The complexes [(L) 2Mn02Mn (L) 2] 3+ where L= 2, 2'-bipyridine or 1, 10-phenanthroline, havebeen examined, in addition to the corresponding (IV, IV) complex of phenanthroline. The crystal structure of the mixed valence (III, IV) com-pound with L= 2, 2'-bipyridine demonstrated that this complex has deeply trapped valences, corresponding to class II in the classification of Robin and Day since the bond lengths differ considerably about the manganese ions. We have examined the electronic spectrum of the (III, IV) complexes and observed broad bands in the near infrared which we have assigned to the mixed valence band expected for a class II system. No comparableband is observed for the phenanthroline (IV, IV) complex. Lowering the pH of (III, IV) dimer solutions reversibly cleaves the antiferromagnetically coupled (III, IV) dimers as determined by the increase in solution magnetic susceptibility; loss of the near infrared band occurs with dimercleavage, although the remainder of the visible spectrum is substantially unaltered. Both absorbance and solution magnetic susceptibility changes with pH are reversible. The solvent dependence of the near infrared band is small but apparently opposite to that predictedby Hush’s theory. However, the bandwidths agree well with those predicted from Hush’s treatment (eg, 0.53 gm_1 predicted, 0.46 ĩ~] observed). A band at 688 cm-1 in the infrared spectrum of the bipyridyl (III, IV) dimer is shifted by isotopic substi-tution with l80, and has been assigned to one of the stretching modes of the bridge; analogous bands are found for the phenanthroline (III, IV) and-(IV, IV) complexes. Pertinent aspects of the electrochemistry are also discussed.In 1972 Plaksin et al. 1 reported the crystal structure of di-^-oxo-tetrakis (2, 2'-bipyridyl) dimanganese (III, IV) perchlorate (hereafter termed the bipyridyl (III, IV) dimer) which was originally synthesized by Nyholm and Turco2 in 1960. This complex, which Nyholm and Turco had formulated as a