Synthesis and Reversible Reductive Coupling of Cationic, Dinitrogen-Derived Diazoalkane Complexes

Curley, John J.; Murahashi, Tetsuro; Cummins, Christopher C.

doi:10.1021/ic900495s

Cited by 18 publications

(10 citation statements)

References 126 publications

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“…In general, these metal complexes are cationic and have ligand‐based LUMOs. This is the case for the diazoalkane amido complexes [Mo{4‐RC 6 H 4 C(H)NN}(N t BuAr) 3 ] + (various R and Ar), which dimerize at the diazoalkane C atom;15 the salophen derivatives [M(salophen)] n + (M=Ni,16 Ti,17 V,17 Mn18), which undergo a reversible dimerization at a ligand C atom; the 2,2′‐bipyridine alkylidyne complex [W(CC 6 H 4 NMe 2 )(κ 2 N 2 ‐bipy)(NCMe)(CO) 2 ] + , which dimerizes at a bipy C atom;19 and the carbene derivative [Cr(=CNEt 2 )(CO) 5 ] + , which dimerizes at the carbene carbon atom 20. It has been reported that the reaction of the titanium complex trans ‐[TiCl 2 (κ 2 N 2 ‐tmeda) 2 ] (tmeda=Me 2 NCH 2 CH 2 NMe 2 ) with acetonitrile leads to the reductive coupling of the latter, affording the dimetallic eneimido derivative trans ‐[Ti 2 Cl 4 {μ‐κ 2 N 2 ‐NC(Me)=(Me)CN}(κ 2 N 2 ‐tmeda) 2 ] 20.…”

Section: Resultsmentioning

confidence: 99%

Reductive Dimerization of Triruthenium Clusters Containing Cationic Aromatic N‐Heterocyclic Ligands

Cabeza¹,

Rı́o²,

Pérez‐Carreño³

et al. 2010

Chemistry A European J

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The cationic cluster complexes [Ru3(μ‐H)(μ‐κ2N,C‐L1 Me)(CO)10]+ (1+; HL1 Me=N‐methylpyrazinium), [Ru3(μ‐H)(μ‐κ2N,C‐L2 Me)(CO)10]+ (2+; HL2 Me=N‐methylquinoxalinium), and [Ru3(μ‐H)(μ‐κ2‐N,C‐L3 Me)(CO)10]+ (3+; HL3 Me=N‐methyl‐1,5‐naphthyridinium), which contain cationic N‐heterocyclic ligands, undergo one‐electron reduction processes to become short lived, ligand‐centered, trinuclear, radical species (1–3) that end in the formation of an intermolecular CC bond between the ligands of two such radicals, thus leading to neutral hexanuclear derivatives. These dimerization processes are selective, in the sense that they only occur through the exo face of the bridging ligands of trinuclear enantiomers of the same configuration, as they only afford hexanuclear dimers with rac structures (C2 symmetry). The following are the dimeric products that have been isolated by using cobaltocene as reducing agent: [Ru6(μ‐H)2{μ6‐κ4N2,C2‐(L1 Me)2}(CO)18] (5; from 1+), [Ru6(μ‐H)2{μ6‐κ4N2,C2‐(L2 Me)2}(CO)18] (6; from 2+), and [Ru6(μ‐H)2{μ4‐κ8N2,C6‐(L3 Me)2}(CO)18] (7; from 3+). The structures of the final hexanuclear products depend on the N‐heterocyclic ligand attached to the starting materials. Thus, although both trinuclear subunits of 5 and 6 are face‐capped by their bridging ligands, the coordination mode of the ligand of 5 is different from that of the ligand of 6. The trinuclear subunits of 7 are edge‐bridged by its bridging ligand. In the presence of moisture, the reduction of 3+ with cobaltocene also affords a trinuclear derivative, [Ru3(μ‐H)(μ‐κ2N,C‐L3′ Me)(CO)10] (8), whose bridging ligand (L3′ Me) results from the formal substitution of an oxygen atom for the hydrogen atom (as a proton) that in 3+ is attached to the C6 carbon atom of its heterocyclic ligand. The results have been rationalized with the help of electrochemical measurements and DFT calculations, which have also shed light on the nature of the odd‐electron species, 1–3, and on the regioselectivity of their dimerization processes. It seems that the sort of coupling reactions described herein requires cationic complexes with ligand‐based LUMOs.

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Section: Resultsmentioning

confidence: 99%

Reductive Dimerization of Triruthenium Clusters Containing Cationic Aromatic N‐Heterocyclic Ligands

Cabeza¹,

Rı́o²,

Pérez‐Carreño³

et al. 2010

Chemistry A European J

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“…[4][5][6][7][8][9][10][11][12] While N 2 elimination from diazoalkanes is generally facile upon reaction with metal complexes, the isolation and characterization of metal-bound diazoalkane adducts is possible and has yielded a plethora of complexes spanning multiple coordination modes. [6,7,13,14] Five coordination modes are possible for a diazoalkane moiety bound to a single transition metal center (Chart 1): κ 1 -N end-on coordination involving the terminal N (type A), [15][16][17][18][19][20][21][22] η 2 -N,N side-on (type B), [23][24][25][26][27][28] η 2 -C,N side-on (type C), κ 2 -C,N metallacyclic (type D), and κ 1 -C coordination (type E). Coordination of a diazoalkane to more than one metal atom is also possible.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, structures, and catalytic reactivity of bis(N-heterocyclic carbene) supported diphenyldiazomethane and 1-azidoadamantane complexes of nickel

Harrold

Corcos

Hillhouse

2016

Journal of Organometallic Chemistry

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“…Radical character of this type is rarely assigned in diazoalkane complexes, but not unprecedented, 9 and a reversible diazoalkane radical coupling reaction has been reported. 38 The electronic flexibility of the diazoalkane is demonstrated by 2-Fe and 2-Co, in which the diazoalkane isomerizes to an η 2 -N,N′ mode that is reduced by two electrons as shown by structural, spectroscopic, and for 2-Co, DFT studies. DFT studies suggest that resonance structure V best describes both the αand β-spin electrons of the η 2 -N,N′ bound diazoalkane (Figure 1).…”

Section: ■ Discussionmentioning

confidence: 99%

“…Although these systems are charge separated, the DFT calculations indicate strong coupling between the corresponding pair of α- and β-electrons (calculated J for 1-Fe , −629 cm –1 ; 1-Co , −909 cm –1 ; 3-Co , −806 cm –1 ). Radical character of this type is rarely assigned in diazoalkane complexes, but not unprecedented, and a reversible diazoalkane radical coupling reaction has been reported …”

Section: Discussionmentioning

confidence: 99%

Iron and Cobalt Diazoalkane Complexes Supported by β-Diketiminate Ligands: A Synthetic, Spectroscopic, and Computational Investigation

et al. 2018

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Diazoalkanes are interesting redox-active ligands and also precursors to carbene fragments. We describe a systematic study of the binding and electronic structure of diphenyldiazomethane complexes of β-diketiminate supported iron and cobalt, which span a range of formal d-electron counts of 7-9. In end-on diazoalkane complexes of formally monovalent three-coordinate transition metals, the electronic structures are best described as having the metal in the +2 oxidation state with an antiferromagnetically coupled radical anion diazoalkane as shown by crystallography, spectroscopy, and computations. A formally zerovalent cobalt complex has different structures depending on whether potassium binds; potassium binding gives transfer of two electrons into the η-diazoalkane, but the removal of the potassium with crown ether leads to a form with only one electron transferred into an η-diazoalkane. These results demonstrate the influence of potassium binding and metal oxidation state on the charge localization in the diazoalkane complexes. Interestingly, none of these reduced complexes yield carbene fragments, but the new cobalt(II) complex LCoPF (L = bulky β-diketiminate) does catalyze the formation of an azine from its cognate diazoalkane, suggesting N loss and transient carbene formation.

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Synthesis and Reversible Reductive Coupling of Cationic, Dinitrogen-Derived Diazoalkane Complexes

Cited by 18 publications

References 126 publications

Reductive Dimerization of Triruthenium Clusters Containing Cationic Aromatic N‐Heterocyclic Ligands

Reductive Dimerization of Triruthenium Clusters Containing Cationic Aromatic N‐Heterocyclic Ligands

Synthesis, structures, and catalytic reactivity of bis(N-heterocyclic carbene) supported diphenyldiazomethane and 1-azidoadamantane complexes of nickel

Iron and Cobalt Diazoalkane Complexes Supported by β-Diketiminate Ligands: A Synthetic, Spectroscopic, and Computational Investigation

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