Cage-Structured Triplatinacyclophanes

Abstract

The synthesis of the tris(triflate) 4 (Scheme 1) has been achieved by means of a straightforward three‐step reaction sequence. After initial lithiation of mesitylene, treatment of the obtained trilithium compound C6H3(CH2Li)3 (2) with oxirane results in the formation of 1,3,5‐tris(3‐hydroxypropyl)benzene (3), which is then transformed to 4 by reaction with (CF3SO2)2O in the presence of pyridine. Whereas 4 reacts with Na2[Os(CO)4] in a somewhat complicated manner, similar reactions with Na[Re(CO)5] and LiPPh2 give the hydrocarbon‐bridged tris(rhenium) complex C6H3[(CH2)3Re(CO)5]3 (5) and the tris(phosphane) C6H3[(CH2)3PPh2]3 (6), respectively. Employing the high‐dilution method, from 6 and Cl2Pt(NCPh)2 the nanoscaled tri‐ and hexaplatinacyclophanes 7 and 9 are available. Owing to the optimal geometry and flexibility of the cage in 7, 1,2‐dichloroethane can be reversibly encapsulated. The molecular structure of 7 · 7 1,2‐Cl2C2H4 was determined by an X‐ray structure analysis. The utility of the reactive metal centers in 7 has been demonstrated by replacing the chloro ligands by acetonitrile to give the cationic platinacyclophane 8, in which, according to NMR studies, the cage‐like structure is preserved.

Self-assembly of nanoscopic coordination cages of D 3h symmetry

“…Although M 3 L 2 -type cages are relatively simple three-dimensional constructs, they remain uncommon. Of those that have been reported (31)(32)(33)(34)(35)(36)(37)(38)(39)(40), most usually either require the use of templates to assemble in solution, or assemble only in the solid state. Part of the reason for this limitation is possibly the fact that, in most cases, flexible ligands were used.…”

Threefold symmetric trimetallic macrocycles formed via the Weak-Link Approach

“…Herein, we report the first application of the Weak-Link Approach to the formation of trimetallic (17)(18)(19)(20) rhodium and iridium macrocycles from a flexible threefold symmetric hemilabile ligand.…”

Trifunctional Phosphane Ligands and Their Application in the Synthesis of Novel Cage-Structured Platinacyclophanes and Trinuclear Chain-Like Platinacycles by Self-Assembly

“…For the generation of the three-dimensional platinacyclophanes 15, 16, and 17 the ligands 11, 12, and 14 were treated with Cl 2 Pt(NCPh) 2 in dichloromethane according to the high-dilution method (Scheme 3). [19] In contrast to the platinacyclophane 1, which was recently described, [16] the smaller cages 15 and 16 were obtained in lower yields. In particular the platinacyclophane 15 could not be isolated in pure form, since polymers and oligomers were formed as by-products, an observation which was also made by Fujita et al with comparable nitrogen ligands.…”

“…Moreover, the structure of 1 was recently confirmed by an X-ray structural analysis. [16] Because 15 was impurified by polymers and because of its low Scheme 4 solubility in all organic solvents, no exact NMR spectroscopic data were available.…”

“…By virtue of its size it was possible to reversibly encapsulate 1,2-dichloroethane into the triplatinacyclophane 1 (Figure 1). [16] In continuation of this work several triplatinacyclophanes were generated with different cage sizes in order to study the dependence of the number of methylene groups in the ligand system on the type of self-assembly. Due to this novel tridentate phosphane ligands are introduced in this investigation.…”