3 research outputs found
Rhenium Selenide Clusters Containing Alkynyl Ligands: Unexpected Reactivity of σ‑Bound Phenylacetylide
Three
organometallic rhenium-based clusters containing phenylacetylide
ligands, [Re6Se8(PEt3)5(CC–Ph)](SbF6) (1) and cis- and trans-[Re6Se8(PEt3)4(CC–Ph)2]
(2 and 3), were synthesized and fully characterized
including single-crystal X-ray diffraction analyses. Reactivity studies
of 1 show that reaction with electrophilic reagents does
not result in the formation of the vinylidene species as predicted;
instead, elimination of the acetylide moiety is observed. Products
isolated from these reactions, including the methyl sulfate complex,
[Re6Se8(PEt3)5(OSO3Me)](SbF6) (4), have been characterized
along with those obtained from the [2 + 2] cycloadditions of 1 with tetracyanoethylene and 7,7,8,8-tetracyanoquinodimethane.
The relative reactivities of the electrophilic agents utilized are
compared. Preliminary computational studies reveal useful information
about the nature of the [Re6Se8]2+–acetylide bond and aid in our understanding of the reactivity
associated with this cluster complex
Preparation of a Family of Hexanuclear Rhenium Cluster Complexes Containing 5-(Phenyl)tetrazol-2-yl Ligands and Alkylation of 5-Substituted Tetrazolate Ligands
The preparation of two new families of hexanuclear rhenium
cluster
complexes containing benzonitrile and phenyl-substituted tetrazolate
ligands is described. Specifically, we report the preparation of a
series of cluster complexes with the formula [Re<sub>6</sub>Se<sub>8</sub>(PEt<sub>3</sub>)<sub>5</sub>L]<sup>2+</sup> where L = benzonitrile, <i>p</i>-aminobenzonitrile, <i>p</i>-methoxybenzonitrile, <i>p</i>-acetylbenzonitrile, or <i>p</i>-nitrobenzonitrile.
All of these complexes undergo a [2 + 3] cycloaddition with N<sub>3</sub><sup>–</sup> to generate the corresponding [Re<sub>6</sub>Se<sub>8</sub>(PEt<sub>3</sub>)<sub>5</sub>(5-(<i>p-</i>X-phenyl)Âtetrazol-2-yl)]<sup>+</sup> (or [Re<sub>6</sub>Se<sub>8</sub>(PEt<sub>3</sub>)<sub>5</sub>(2,5-<i>p-</i>X-phenyltetrazolate)]<sup>+</sup>) cluster
complexes, where X = NH<sub>2</sub>, OMe, H, COCH<sub>3</sub>, or
NO<sub>2</sub>. Crystal structure data are reported for three compounds:
[Re<sub>6</sub>Se<sub>8</sub>(PEt<sub>3</sub>)<sub>5</sub>(<i>p</i>-acetylbenzonitrile)]Â(BF<sub>4</sub>)<sub>2</sub>•MeCN,
[Re<sub>6</sub>Se<sub>8</sub>(PEt<sub>3</sub>)<sub>5</sub>(2,5<i>-</i>phenyltetrazolate)]Â(BF<sub>4</sub>)•CH<sub>2</sub>Cl<sub>2</sub>, and [Re<sub>6</sub>Se<sub>8</sub>(PEt<sub>3</sub>)<sub>5</sub>(2,5<i>-p-</i>aminophenyltetrazolate)]Â(BF<sub>4</sub>). Treatment of [Re<sub>6</sub>Se<sub>8</sub>(PEt<sub>3</sub>)<sub>5</sub>(2,5<i>-</i>phenyltetrazolate)]Â(BF<sub>4</sub>) with HBF<sub>4</sub> in CD<sub>3</sub>CN at 100 °C leads to
protonation of the tetrazolate ring and formation of [Re<sub>6</sub>Se<sub>8</sub>(PEt<sub>3</sub>)<sub>5</sub>(CD<sub>3</sub>CN)]<sup>2+</sup>. Surprisingly, alkylation of the phenyl and methyl
tetrazolate complexes ([Re<sub>6</sub>Se<sub>8</sub>(PEt<sub>3</sub>)<sub>5</sub>(2,5<i>-</i>N<sub>4</sub>CPh)]Â(BF<sub>4</sub>) and [Re<sub>6</sub>Se<sub>8</sub>(PEt<sub>3</sub>)<sub>5</sub>(1,5<i>-</i>N<sub>4</sub>CMe)]Â(BF<sub>4</sub>)) with methyl iodide
and benzyl bromide, leads to the formation of mixtures of 1,5- and
2,5-disubstituted tetrazoles
Reversible Electrochemical Lithium-Ion Insertion into the Rhenium Cluster Chalcogenide–Halide Re<sub>6</sub>Se<sub>8</sub>Cl<sub>2</sub>
The cluster-based
material Re<sub>6</sub>Se<sub>8</sub>Cl<sub>2</sub> is a two-dimensional
ternary material with cluster–cluster bonding across the <i>a</i> and <i>b</i> axes capable of multiple electron
transfer accompanied by ion insertion across the <i>c</i> axis. The Li/Re<sub>6</sub>Se<sub>8</sub>Cl<sub>2</sub> system showed
reversible electron transfer from 1 to 3 electron equivalents (ee)
at high current densities (88 mA/g). Upon cycling to 4 ee, there was
evidence of capacity degradation over 50 cycles associated with the
formation of an organic solid–electrolyte interface (between
1.45 and 1 V vs Li/Li<sup>+</sup>). This investigation highlights
the ability of cluster-based materials with two-dimensional cluster
bonding to be used in applications such as energy storage, showing
structural stability and high rate capability