Polycyclic polystannanes

As late as 1988, there were no known examples of polycyclic polystannanes reported in the literature. However, through the careful fractionation of complex mixtures of products obtained from various oligomeriza-... 

As shown in Scheme 19, the first example of a polycyclic polystannane, the bicyclo[2.2.0]hexastannane 87, was obtained from fractionation of the... 

All of the polycyclic polystannanes reported to date are thermally robust in solution to temperatures of at least 200°C. For the bicyclo[2.2.0]hexa-slannane derivative 87, this is not too surprising, since the calculated strain-energy value for the parent compound is still ca. 12 kcal mol" less than the parent cyclotristannane system (102). However, the parent perstanna-[ ]-prismanes for n = 4 and 5 are expected to be more ring-strained than cyclotristannane (cf. 73.2 and 61.0 kcal mol" , respectively) (99,I04) therefore, the thermal stability of the two compounds, 90 and 91, suggest that these compounds are kinetically stable by virtue of signifi-... 

ABSTRACT. Several new classes of polycyclic polystannanes have been prepared and these compounds have been fully characterized by spectroscopic methods, including crystallographic analysis. The information obtained horn these investigations should prove useful in predicting the structure and properties of extended macroscopic materials containing tin, such as the currently unknown polystannynes, [RSn]n-... 

We have found that if the thermolysis of the cyclotristannane 1 is carried out with benzophenone at 200° C, two new polycyclic polystannanes, 7 and 8, which are members of the perstanna-[n]-prismane, [RSn]2n, series of compounds, can be isolated by column chromatograpy in a 1 2.3 ratio for a combined yield of 12% [11,12]. Since the octastanna-[4]-prismane 7 and the decastanna-[5]-prismane 8 display different physici and chemical properties, an investigation of these compounds reveals important information concerning the impact that bond angle distortions have on the electronic structure and thermodynamic stability of heavy atom Group IVA polycyclic compounds. 

RSn]2o will be that of the dodecastanna-[10]-prismane rather than that of dodecastanna-dodecahedron. Currently, work is in progress to substantiate these views and the molecular and electronic structures of the new polycyclic polystannanes which are discovered in the process will undoubtedly help to formulate our ideas concening the factors which govern the i ysical and chemical properties of Group IVA heavy atom M-M bonded netwoiks. 

We thank Dr. Cynthia Day of Crystalytics Co. for the crystallographic analysis of the polycyclic polystannanes and the Office of Naval Research and the Nation Science Foundation (Grant CHE-9(X)1462) for support of this woric. Acknowledginent is also made to the donors of the Petroleum Research Fund, administered by the ACS, for partial support of this research. 

The Molecular and Electronic Structure of Polycyclic Polystannanes Lawrence R. Sita and Isamu Kinoshita... 

The interesting properties of the poly(silylenes) are then described in the remaining papers. Included are efforts on the nonlinear optical behavior, photoconducting properties, and phase and solution behavior. A paper on polycyclic polystannanes completes this topic. 

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