Synthesis of the First Oxaphosphirane Iron Complexes

Streubel, Rainer; Volk, Niklas; Schnakenburg, Gregor; Alcaraz, Antonio García; Ferao, Arturo Espinosa

doi:10.1002/ejic.202000812

Cited by 4 publications

(5 citation statements)

References 25 publications

(23 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similarly, the saturation magnetization behavior of 4 collected at 11905 cm −1 is well described by a S=1 positive zero‐field split (+ZFS) non‐Kramers doublet with ground‐state spin‐Hamiltonian parameters D =27±5 cm −1 , E/D=0.10±0.05 and g=2.25±0.05 (Figure 3H). While there are very few examples of saturation magnetization data for S=1 ground states of iron, the large D value observed here is consistent with those previously reported [46,47,51] …”

Section: Resultssupporting

confidence: 93%

“…These deviations are often observed in transition metal S=1 complexes [43–45] and suggest the ligand environments in these species result in large spin‐orbit couplings. As examples and electronic structure and magnetization data for S=1 iron systems are limited, [46,47] we employed MCD and density functional theory (DFT) to further investigate the electronic structure of these complexes.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

NHC Effects on Reduction Dynamics in Iron‐Catalyzed Organic Transformations**

Wolford

Muñoz

Neate

et al. 2021

Chemistry A European J

View full text Add to dashboard Cite

The high abundance, low toxicity and rich redox chemistry of iron has resulted in a surge of iron‐catalyzed organic transformations over the last two decades. Within this area, N‐heterocyclic carbene (NHC) ligands have been widely utilized to achieve high yields across reactions including cross‐coupling and C−H alkylation, amongst others. Central to the development of iron‐NHC catalytic methods is the understanding of iron speciation and the propensity of these species to undergo reduction events, as low‐valent iron species can be advantageous or undesirable from one system to the next. This study highlights the importance of the identity of the NHC on iron speciation upon reaction with EtMgBr, where reactions with SIMes and IMes NHCs were shown to undergo β‐hydride elimination more readily than those with SIPr and IPr NHCs. This insight is vital to developing new iron‐NHC catalyzed transformations as understanding how to control this reduction by simply changing the NHC is central to improving the reactivity in iron‐NHC catalysis.

show abstract

Section: Resultssupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

NHC Effects on Reduction Dynamics in Iron‐Catalyzed Organic Transformations**

Wolford

Muñoz

Neate

et al. 2021

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…2 Recently, the reactions of Li/Cl phosphinidenoid tungsten(0) and iron(0) carbonyl complexes with aldehydes were computationally studied using P-methyl-substituted model derivatives and diethylene glycol dimethyl ether (DEGDME) instead of 12c4 to provide an I-type almostsaturated coordination sphere for the Li cation. 74 Also very recently, the dichotomy between phosphinidene and phosphinidenoid complexes was explored for the case of Pdiorganylamino-substituted Li/Cl phosphinidenoid tungsten(0) complexes. 50 In coordinating solvents (e.g., THF) and in the presence of 12c4, full dissociation of the P−Li bond into contact ion pairs of type K (S = THF, 12c4) (Figure 4) explains the characteristic "phosphinidenoid" reactivity in insertion reactions into polar E−H bonds (E = OMe, N(H)Me), such as those depicted in Scheme 5.…”

Section: ■ Typical Intermolecular Reactionsmentioning

confidence: 99%

“…For the same compound (R = Me, X = F, S = Et 2 O), a weakening of the P–F bond in terms of lower relaxed force constant, roughly paralleling a distance elongation, was observed in the series from neutral phosphane H 2 PF ( k 0 = 4.24 mdyn/Å, d = 1.634 Å) to naked phosphanido anion [MePW(CO) 5 ] − ( k 0 = 2.95 mdyn/Å, d = 1.701 Å) to I ( k 0 = 2.76 mdyn/Å, d = 1.699 Å) and K ( k 0 = 1.85 mdyn/Å, d = 1.744 Å), thus supporting increased ease of lithium fluoride elimination . Recently, the reactions of Li/Cl phosphinidenoid tungsten(0) and iron(0) carbonyl complexes with aldehydes were computationally studied using P -methyl-substituted model derivatives and diethylene glycol dimethyl ether (DEGDME) instead of 12c4 to provide an I -type almost-saturated coordination sphere for the Li cation …”

Section: Quantum-chemical Calculationsmentioning

confidence: 99%

M/X Phosphinidenoid Metal Complex Chemistry

et al. 2021

Self Cite

View full text Add to dashboard Cite

Conspectus Like singlet carbenes and silylenes, transient electrophilic terminal phosphinidene complexes enabled highly selective synthetic transformations, but the required multistep synthetic protocols precluded widespread use of these P1 building blocks. By contrast, nucleophilic M/Cl phosphinidenoid complexes can be easily accessed in one step from [M(CO) n (RPCl2)] complexes. This advantage and the mild reaction conditions opened broad synthetic applicability that enabled access to a variety of novel compounds. The chemistry will be described in this Account, including bonding and mechanistic considerations derived from high-level density functional theory calculations. In 2007, we gained the first strong evidence for the formation of these thermally labile complexes using two different synthetic approaches: P–H deprotonation and Cl/Li exchange; the latter has become the preferred method. Intense studies revealed that steric demand of the P substituents in combination with metal complexation, a donor solvent, and/or the presence of a crown ether are necessary prerequisites for the formation and especially the usability of these intermediates as novel P1 building blocks. Solution-phase NMR spectroscopy and solid-state X-ray diffraction studies revealed the bonding situation, i.e., a solvent-separated ion pair structure, and typical 31P NMR signatures of the anions. To date, we have established the following reactivity patterns for Li/Cl phosphinidenoid complexes: self-condensations (I), electrophilic and nucleophilic reactions (II), 1,1-additions (III), [2 + 1] cycloadditions (IV), ring expansions (V), and redox reactions (VI). For example, self-condensations can yield dinuclear acyclic or polycyclic diphosphane or diphosphene complexes. Their use as nucleophiles and electrophiles can be employed to access functional phosphane ligands with mixed substitution patterns. 1,1-Addition reactions were a puzzling discovery because the resulting products resembled classical P–C π-bond structures but the bonding was more of a donor-to-phosphorus adduct with significant differences in bonding parameters. Into the same category and also surprising fall formal E–H insertion reactions leading to 1,1′-bifunctional phosphane complexes. To date, the most important synthetic impact was achieved in the chemistry of strained P-heterocyclic ligands such as oxaphosphiranes and azaphosphiridines, obtained via [2 + 1] cycloadditions of the title compounds with carbonyls and imines, respectively. Ring expansions have been shown to yield 1,2-oxaphosphetanes and 1,2-thiaphosphetanes, and because of the pool of industrially important epoxides, this provides straightforward and affordable access to these novel P-heterocyclic ligands, which also promise to be of interest in catalytic applications. Recent developments describe redox transformations of Li/Cl phosphinidenoid complexes into new reactive intermediates such as complexes with open-shell P-functional phosphanyl ligands via oxidative single electron transfer reactions or into te...

show abstract

“…9 This was followed by phosphinidene complex transfer reactions to carbonyls. 10 But the full scope of oxaphosphirane ligand structures (type IV ) was achieved only with the advent of the Li/Cl phosphinidenoid complex route in 2007 (Scheme 1), which was recently reviewed by us. 11 To the best of our knowledge, only theoretical studies on formation/conversion as well as properties of oxaphosphiranes are known to date.…”

mentioning

confidence: 99%