Probing Conformational Strain in Multinuclear Lewis Acids: Synthesis, Spectroscopic and Structural Characterization of the Dinuclear Ferroceneboronic Ester (eta(5)-C5H5)Fe(eta(5)-C5H4)BO2C5H8O2B(eta(5)-C5H4)Fe(eta(5)-C5H5)

Journal article

The facile linking of ferrocene units into multinuclear frameworks via boronic ester condensation chemistry is demonstrated through the synthesis of (η5-C5H5)Fe(η5-C 5H4)BO2C5H8O 2B(η5-C5H4)Fe(η5- C5H5), which has been characterized by standard spectroscopic techniques and its structure (as the chloroform solvate) determined crystallographically. The crystal structure reveals the following properties: monoclinic, space group P21/n with a = 22.5093(3), b = 5.8951(3), c = 22.9770(5) Å, β = 119.110(1)°, Z = 4, R = 0.059 and wR2 = 0.123 for observed reflections I > 2σ(I). The molecular structure is characterized by two planar, three-coordinate boron centres (∑angles at boron = 360° within the standard 3σ limit) featuring B-O bond lengths of 1.358(6)-1.371(6) Å and B-C distances of 1.539(7) and 1.553(7) Å. The pentaerythritol linker ensures that the core of the molecule is non-linear, with the B(1)•••C(1) •••B(2) angle being 140.1°. Moreover, the corresponding angle measured for the macrocycle [(η5-C5H 4)Fe(η5-C5H4)BO 2C5H8O2B]2 is only slightly narrower (137.6°), implying that the formation of such a macrocyclic ring does not necessitate a large structural distortion, and hence that the degree of resulting ring strain is likely to be minor. © 2009 Springer Science+Business Media, LLC.

Authors: Day, J; Thompson, A; Aldridge, S

• Publication status: Published
• Journal: JOURNAL OF CHEMICAL CRYSTALLOGRAPHY
• Volume: 40
• Issue: 2
• Pages: 156-159
• Publication date: 2010-02-01
• DOI: 10.1007/s10870-009-9624-y
• EISSN: 1572-8854
• ISSN: 1074-1542
• Language: English
• Keywords: Boron; Iron; Multinuclear complexes; Ferrocene; Boronic ester