Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Petersenstrasse 20, 64287 Darmstadt, Germany.
J Phys Chem A. 2009 Nov 5;113(44):12115-21. doi: 10.1021/jp906140b.
Endohedral clusters, formed by incorporating a single Mn atom into a cage of tin atoms, have been generated in the gas phase. Mass spectrometry reveals that a cage size of 10 tin atoms is necessary for the efficient incorporation of one Mn atom. Some of the cluster compounds with one Mn atom attached to the tin clusters display large intensities compared to the pure tin clusters, indicating that the compound clusters are particularly stable. The manganese-doped tin cluster assemblies Mn@Sn12, Mn@Sn13, and Mn@Sn15 have been further analyzed within a molecular beam magnetic deflection experiment. Interestingly, although the effect of the magnetic field on the behavior of Mn@Sn12 is quite different from that of Mn@Sn13 and Mn@Sn15, the magnetic dipole moments are the same within the uncertainty of the measurements. Magnetic dipole moments have been found in close agreement with the spin quantum number S = 5/2 predicted by theory for Mn@Sn12, indicating that the magnetic moment of the Mn atom is not quenched. This supports the idea that within a tin cluster cage a single Mn atom can be encapsulated, resulting in the formation of endohedral clusters consisting of a central Mn2+ ion surrounded by a particularly stable Zintl-ion cage Sn(N)(2-). The observed molecular beam profiles indicate that at a nozzle temperature of 55 K the magnetic moment is strongly locked to the molecular framework of Mn@Sn12; in contrast, the magnetic moment of Mn@Sn13 and Mn@Sn15 tends to align with the magnetic field. The experiments therefore demonstrate that the size of a presumably nonmagnetic cluster cage might have a fundamental influence on the magnetization dynamics of paramagnetic species. The influence of vibrational excitation on the Stern-Gerlach profile of Mn@Sn12 is further analyzed, and it is shown that the behavior of Mn@Sn12 at elevated nozzle temperatures changes continuously toward a nonlocked moment, pointing to size- and temperature-dependent magnetization dynamics.
笼型内包物簇合物是由一个锰原子嵌入锡原子形成的笼型结构中生成的。质谱分析表明，要有效地将一个锰原子嵌入锡原子的笼型结构中，锡原子的笼型大小需要达到 10 个。与纯锡原子簇相比，一些附着有一个锰原子的簇化合物显示出较大的强度，这表明这些化合物的簇合物特别稳定。在分子束磁偏转实验中，进一步分析了掺杂锰的锡原子簇组装体 Mn@Sn12、Mn@Sn13 和 Mn@Sn15。有趣的是，尽管磁场对 Mn@Sn12 行为的影响与 Mn@Sn13 和 Mn@Sn15 的影响完全不同，但磁偶极矩在测量的不确定度内是相同的。磁偶极矩与理论预测的 Mn@Sn12 的自旋量子数 S = 5/2 非常吻合，表明锰原子的磁矩没有被猝灭。这支持了这样一种观点，即在锡原子簇笼中可以封装单个锰原子，从而形成由中心 Mn2+ 离子被一个特别稳定的 Zintl 离子笼 Sn(N)(2-) 包围的内包物簇合物。观察到的分子束轮廓表明，在喷嘴温度为 55 K 时，磁矩强烈锁定在 Mn@Sn12 的分子框架中；相比之下，Mn@Sn13 和 Mn@Sn15 的磁矩倾向于与磁场对齐。因此，实验表明，一个假定的非磁性簇笼的大小可能对顺磁性物质的磁化动力学有根本的影响。进一步分析了振动激发对 Mn@Sn12 的斯特恩-盖拉赫轮廓的影响，结果表明，在较高的喷嘴温度下，Mn@Sn12 的行为连续地向非锁定磁矩转变，这表明磁化动力学与尺寸和温度有关。
