The Missing Parent Compound [(C5H5)Fe(η5-P5)]: Synthesis, Characterization, Coordination Behavior and Encapsulation

The so far missing parent compound of the large family of pentaphosphaferrocenes [CpFe(eta(5)-P-5)] (1 b) was synthesized by the thermolysis of [CpFe(CO)(2)](2) with P-4 using the very high-boiling solvent diisopropylbenzene. It was comprehensively characterized by, inter alia, NMR spectroscopy, single crystal X-ray structure analysis, cyclic voltammetry and DFT computations. Moreover, its coordination behavior towards Cu-I halides was explored, revealing the unprecedented 2D polymeric networks [{CpFe(eta(5:1:1:1:1)-P-5)}Cu-2(mu-X)(2)](n) (2 a: X=Cl, 2 b: X=Br) and [{CpFe(eta(5:1:1)-P-5)}Cu(mu-I)](n) (3) and even the first cyclo-P-5-containing 3D coordination polymer [{CpFe(eta(5:1:1)-P-5)}Cu(mu-I)](n) (4). The sandwich complex 1 b can also be incorporated in nano-sized supramolecules based on [Cp*Fe(eta(5)-P-5)] (1 a) and CuX (X=Cl, Br, I): [CpFe(eta(5)-P-5)]@[{Cp*Fe(eta(5)-P-5)}(12)(CuX)(20-n)] (5 a: X=Cl, n=2.4; 5 b: X=Br, n=2.4; 5 c: X=I, n=0.95). Thereby, the formation of the CuI-containing fullerene-like sphere 5 c is found for the first time.

Automated summary

The parent compound of pentaphosphaferrocenes was successfully synthesized and characterized comprehensively. Its coordination behavior towards Cu-I halides was explored, revealing unprecedented polymeric networks, and it was also incorporated in nano-sized supramolecules. The formation of a CuI-containing fullerene-like sphere was discovered for the first time.