Metal−Metal Communication through Carborane Cages Supporting Electroactive [η⁵-CpFe(CO)₂] Substituents

Abstract

A family of η 5 -CpFe(CO) 2 -substituted closo-carboranes was synthesized and characterized, including cyclic voltammetry measurements. Like the previously reported bimetallic compound 1,12-[η 5 -CpFe(CO) 2 ] 2 -1,12-C 2 B 10 H 10 (8), 1,10-[η 5 -CpFe(CO) 2 ] 2 -1,10-C 2 B 8 H 8 (9) produces two dissimilar and irreversible one-electron oxidations within the same range, suggesting that it also exhibits through-cage electronic communication between iron centers. Structures determined by X-ray diffraction studies are reported for 1-[η 5 -CpFe(PPh 3 )(CO)]-1,12-C 2 B 10 H 11 (5), 1,12-[η 5 -CpFe(CO) 2 ] 2 -1,12-C 2 B 10 H 10 (8), and 1,10-[η 5 -CpFe(CO) 2 ] 2 -1,10-C 2 B 8 H 8 (9).

Site Selectivity in the Reactions of the Hexanuclear Platinum Cluster [Pt6(μ‐PtBu2)4(CO)6][CF3SO3]2

“…Bond a (Scheme 2) are constantly lengthened from 2.696(1) to 2.801 (1) in the series XY = halides, alkynyls, CO, PMe 3 , Table 2. Selected bond lengths [] and angles [8] in the isotypic structures of compounds 3, 5 and 6. The apexes in the atom labels have the meaning shown in Figure 1.…”

“…Selected bond lengths [] and angles [8] in the structure of 9-Y 2 ·CHCl 3 . 2 + as it appears in the structure of 9-Y 2 ·CHCl 3 .…”

“…[2] The synthetic procedures employ different types of inorganic or organometallic "bricks", from simple mononuclear L n M fragments [1][2][3] to dinuclear, [4] metal-chain, [5] porphyrin, [1a, 6] polyoxometalate, [7] carborane, [8] C60 [9] or dendrimeric [10] units, generally connected by organic bridging ligands or spacers. Owing to the peculiar redox properties of transition-metal clusters, [11] there is also a growing interest in the construction of rigid-rod or dendrimeric structures in which two [12] or more [13,14] cluster units are connected by conjugated or insulating spacers.…”

Improved syntheses of bis(ethynyl)-para-carboranes, 1,12-(RCC)2-1,12-C2B10H10 and 1,10-(RCC)2-1,10-C2B8H8 (R=H or Me3Si)

“…The effect on the cage framework by the ethenyl groups in 8 is somewhat comparable to the effects by aryl and ethynyl groups. While there are many structurally characterised 1,12-disubstituted-paracarboranes, only three 1,10-disubstituted-para-carboranes, 1,10-X 2 -1,10-C 2 B 8 H 8 , have been characterised by X-ray crystallography [3,10]. The cage geometries in these compounds are summarised in Table 1 along with 10 and MP2-optimised [13] geometries of 5 and 7.…”

“…These compounds have found use as precursors to molecular rigid rods, and by extension as components in supramolecular assemblies with defined and persistent shape. In addition to the structural properties offered by these rod-like building blocks, which offer approximately cylindrical symmetry along the long molecular axis, the ''three dimensional'' aromaticity offered by the cage [1], and the analogy with 1,4-diethynyl benzene, 1,4-(HC"C) 2 C 6 H 4 , has prompted consideration of diethynylcarboranes as conduits for electronic effects [2][3][4].…”