Sumanene complex

The CpRu+ sumanene complex 17 (Fig. 35.13) was synthesized similarly to 15 and 16 [51]. Unlike them, a pair of two species was observed in the NMR spectra of [CpRu(sumanene)]PFg (17). The major and minor species were assigned to... 

The coordination chemistry of sumanene (1) reported to date was reviewed here. Stepwise selective benzylic lithiation of 1 was presented. The benzylic anion species exhibits the bowl-to-bowl inversion. Recent study on 1 revealed that the single crystal of 1 shows high electron transport ability with anisotropy [52]. In the prospective view, trapping of such anion is considered to enable various substitutions at the benzylic positions stereoselectively, which is one of the promising approaches to create the functional materials based on 1. Complexation with CpFe+ demonstrated selective formation of the first concave-bound complex, which is expected to lead to the inclusion complexes of n bowls. The inversion behavior observed in the CpRu+ complex may provide the idea of a dynamic catalytic system. Thus, some characteristic features of sumanene complexes are becoming apparent. In the future, n bowls such as 1 are expected to provide novel electrical materials, organometallic catalysts, etc. 

The methylene bridge of sumanene can be used for C-C bond formation for expanding the backbone of the n -bowl. The synthesis started with bromosumanene 125, which was generated by selective monobromination of 2 with HBr3 pyridine complex (Scheme 44) [156]. The Suzuki coupling of 125 with 2-formylphenylboronic... 

Concave-j -Bound Cyclopentadienyl Iron Cation Complex of Sumanene... 

The complexation of 1 with CpFe+ was performed by ligand exchange with a Cp group of ferrocene [47]. The reaction proceeded in the presence of aluminum powder and aluminum chloride without a solvent under argon at 120 °C for 19 h. The counteranion of the crude complex was replaced by hexafluorophosphate, giving [CpFe(sumanene)]PFg (15) as an orange solid. The use of excess ferrocene and aluminum chloride selectively afforded the desired monometallated complex in 91% yield (Scheme 35.2). However, the reaction in decahydronaphthalene as a solvent did not yield 15 [47]. The complex 15 was fully characterized by fast atom bombardment (FAB) mass spectrometry, and C NMR spectroscopy, and X-ray crystallography. 

Furthermore, the methyl-substituted complex [MeCpFe( j -sumanene)]PFg was synthesized. H NMR experiments suggested that the methyl group is directed out of the bowl with a restricted rotation [49]. 

The selective synthesis of the concave-bound complex [CpFe(sumanene)]PF6 is achieved by ligand exchange of ferrocene with sumanene (Schane 3.46) [ 146,147]. The structure is confirmed in both solution and soUd states. This is the first report for the selective synthesis of concave-bound it-bowl complexes (Fig. 3.34). The curved concave Jt surface serves as an ligand. The selectivity of the complexadon is theoretically discussed [148], The redox properties of the complex are investigated through electrochemical study. The complex exhibits the Fe(II)/Fe(I) reduction, which displays features of partial chemical reversibihty, coupled to the fragmentation of the corresponding Fe(I) species to ferrocene [149],... 

Synthesis of an Fe(II) complex of sumanene having a Cp ligand with chiral 3 -butyl group attached is performed in a similar manner to the preparation of [CpFe(sumanene)]PF6. The complex also shows a concave-face selective coordination in solution, in which the rotation of the Cp ring is restricted. Magnetic and optical desymmetrization in the sumanene ligand is found in the complex (Fig. 3.35) [150]. This is the first optical active complex with a tt-bowl ligand. 

CpRu(sumanene)]PFresulting complex is a mixture of concave- and convex-binding of CpRu, where concave-binding is much preferable. The dynamic isomerization via bowl-to-bowl inversion between them is observed in solution (Scheme 3.47) [152]. The preference can be accounted for by the thermodynamic stability. 

Another t-conjugated system depends on nonplanar k bowl, sumanene, which is a partial Csv structure of Ceo- The t-bowl chemistry of sumanene has been developed together with derivatization of sumanene through use of the benzylic positions. Complexation with nonplanar t-conjugated plane leads to various coordination modes including selective concave and convex complexation. Thus-obtained complexes are envisioned to exhibit unique reactivities due to coordination to nonplanar K surface [5]. 

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