The chemistry of hydridocarbonylferrates revisited: syntheses and structures of the new [H2Fe4(CO)12]2− and [HFe5(CO)14]3− anions, and the [Fe(DMF)4][Fe4(CO)12(μ5-η2-CO)(μ-H)]2 adduct containing an unprecedented isocarbonyl

Abstract

The di-hydride di-anion [H(2)Fe(4)(CO)(12)](2-) has been quantitatively obtained by protonation of the previously reported mono-hydride tri-anion [HFe(4)(CO)(12)](3-) in DMSO and structurally characterised in its [NEt(4)](2)[H(2)Fe(4)(CO)(12)] salt. It shows some subtle but yet significant differences in the stereochemistry of the ligands in comparison to the heavier Ru(4) and Os(4) congeners. The study of the reactivity of these [H(4 -n)Fe(4)(CO)(12)](n-) (n = 2,3) species allowed the serendipitous isolation and structural characterization of the new pentanuclear [HFe(5)(CO)(14)](3-) mono-hydride tri-anion. Attempts to obtain the latter in better yields led to the discovery of intermolecular CO/H(-) mutual exchange reactions and isolation and structural characterization of the [Fe(DMF)(4)][Fe(4)(CO)(12)(μ(5)-η(2)-CO)(μ-H)](2)·0.5CH(2)Cl(2) and [M(+)][Fe(4)(CO)(12)(μ(4)-η(2)-CO)(μ-H)](-) (M = K, Cs) adducts, the former containing an unprecedented isocarbonyl group. The isolation of new tetranuclear and, above all, pentanuclear hydridocarbonylferrates indicates that it is possible to further expand the chemistry of homoleptic Fe carbonyl species.

Multinuclear iron–phenyl species in reactions of simple iron salts with PhMgBr: identification of Fe4(μ-Ph)6(THF)4 as a key reactive species for cross-coupling catalysis

“…The Fe–Fe bond distances in 2b and 2c range from 2.3751(9) Å to 2.5532(10) Å, which are notably shorter compared to reported tetranuclear iron species such as [Fe 4 (CO) 12 (CCH 3 )] – , [(η 5 -C 5 H 4 Me) 4 Fe 4 (μ 3 -CH) 2 (μ 3 -CNPh) 2 ](PF 6 ) 2 , and [Fe 4 (CO) 12 (μ 3 -CO)] 2– , where the Fe–Fe bond distances typically range from 2.469 Å to 2.618 Å. 41 – 44 Interestingly, a [Fe 8 Me 12 ] – cluster has been previously isolated and characterized as a key intermediate in reactions involving simple ferric salts and MeMgBr. 45 The Fe–Fe distances in [Fe 8 Me 12 ] – are closer to the Fe–Fe distances in 2b and 2c , ranging from 2.4188(15) to 2.4514(15) Å.…”

Reactivity of hydride bridges in a high-spin [Fe3(μ-H)3]3+ cluster: reversible H2/CO exchange and Fe–H/B–F bond metathesis

“…22 The (μ n -H)Fe n fragment ( n > 2) was previously unknown in the high-spin state ( vide infra ), and 2 is the first example of an internal μ 3 -hydride in polyiron chemistry; face-capping μ 3 -hydrides are well-known in iron carbonyl clusters. 23 …”

Synthesis, molecular structure and fluxional behavior of the elusive [HRu4(CO)12]3−carbonyl anion

“…[15][16][17] Nonetheless, it must be remarked that 3 and [H 2 Fe 4 (CO) 12 ] 2− are isostructural. 10 Comparison of [H 4−n Ru 4 (CO) 12 ] n− (n = 0-3) and [H 4−n Fe 4 (CO) 12 ] n− (n = 2-3) indicates that Ru prefers less charged poly-hydride species, whereas more charged anions are favored in the case of Fe. This may be explained by assuming higher basicity for the Ru cluster anions compared to the related Fe species.…”