Uncovering Multiple Metal–Metal Bonding in a Tetranuclear Fluoride Rhenium Cluster or the Curious Case of {[Ni(H2O)6](NH4)4}[Re4F18]·4H2O

Document Type

Article

Publication Date

9-24-2019

Publication Title

European Journal of Inorganic Chemistry

Volume

2019

Issue

38

First page number:

4129

Last page number:

4135

Abstract

The compound {[Ni(H2O)6](NH4)4}[Re4F18]·4H2O (1) has been isolated and characterized by single-crystal X-ray diffraction, Raman spectroscopy and computational methods. The compound 1 crystallizes in the triclinic space group P1 (a = 6.6620(9) Å, b = 9.7121(13) Å, c = 11.2007(15) Å, α = 67.644(2)°, β = 83.827(2)°, γ = 84.366(2)°). In 1, the [Re4F18]6– anion is composed of four Re(III) atoms bridged by two µ-bridging fluorine atoms and two di-µ-bridging fluorine atoms. In [Re4F18]6–, the shortest Re–Re distance (i.e., 2.3631(6) Å) is characteristic of the presence of a Re=Re double bond; the Re–F distances range from 1.854(6) to 2.008(5) Å. Theoretical calculations confirm the presence of a weak Re=Re double bond; the Mayer–Mulliken bond order of the doubly bridged Re atoms is 1.8097 and the natural localized molecular orbital bond order is 1.8751. The Raman spectrum of 1 has been measured and shows a series of bands in the region 167–1449 cm–1 that have been attributed to Re–F and Ni–O stretches, Re4F18 ring breathing and NH4 + bending and libration modes.

Keywords

Metal-metal bonds; Rhenium; Fluorine; Cluster compounds; Structure elucidation

Disciplines

Chemistry | Inorganic Chemistry | Physical Sciences and Mathematics

Language

English

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