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1.
Inorg Chem ; 2020 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-32698569

RESUMO

The synthesis and characterization of V(═O){N(SiMe3)2}3 (1), V(═NSiMe3){N(SiMe3)2}3 (2), and V(═NSiMe3)(OSiMe3){N(SiMe3)2}2 (3) are described. Prior attempts to synthesize the vanadium(V) oxo complex 1 via salt metathesis of VOCl3 with the lithium or sodium silylamide salt had yielded either the putative rearranged species V(═NSiMe3)(OSiMe3){N(SiMe3)2}2 (3) or the oxo-bridged, dimetallic {(µ-O)2V2[N(SiMe3)2]4}. We now show that complex 1 is available by treatment of the vanadium(III) tris(silylamide) V{N(SiMe3)2}3 with iodosylbenzene. The imido complex 2 was obtained by treatment of V{N(SiMe3)2}3 with trimethylsilyl azide. Sublimation of 1 formed complex 3, which was determined to be V(═NSiMe3)(OSiMe3){N(SiMe3)2}2, on the basis of infrared, electronic, and 1H and 51V NMR spectroscopies. Crystallographic disorder precluded a complete structural characterization of 3, although a four-coordinate V atom, as well as severely disordered ligands, were apparent. Comparison of the vibrational spectra of 1 and 2 allowed an unambiguous assignment of the V-O (995 cm-1) and V-Nimide (1060 cm-1) stretching bands. The vibrational spectrum of complex 3 displayed strong absorbances at 1090 and 945 cm-1, indicative of its metal imide and metal siloxide moieties. The 1H NMR spectrum of 1 in deuterated benzene showed overlapping signals for the ligand protons proximal and distal to the oxo moiety at 0.52 and 0.38 ppm. The 1H NMR spectrum of 2 in deuterated methylene chloride displayed distinct signals for the imido (0.41 ppm) and amido (0.35 ppm) protons, whereas 1H NMR spectroscopy of 3 showed three signals in an intensity ratio consistent with the formula V(═NSiMe3)(OSiMe3){N(SiMe3)2}2. 51V NMR spectra of 1-3 revealed singlet resonances at -119 ppm (1), -24 ppm (2), and -279 ppm (3). The electronic spectra of 1-3 displayed single absorbances in the charge transfer region, consistent with their d0 electron configurations. Kinetic studies of the spontaneous conversion of complex 1 to 3 were used to determine the rate constants (ca. 0.0002 s-1 (63 °C), 0.0006 s-1 (73 °C), 0.002 s-1 (83 °C)) and activation energy (ca. 20 kcal/mol) of this first-order process.

2.
Dalton Trans ; 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32236283

RESUMO

Second order Jahn-Teller (SOJT) effects arise from interactions between filled and empty molecular orbitals of like symmetry. These interactions often lead to structural distortions whose extent is inversely proportional to the energy difference between the interacting orbitals. The main objectives of the work described here are (1) the calculation (using density functional theory methods) of the energies of the valence molecular orbitals in the species EH3 (E = N, P, As or Sb), HEEH (E = C, Si, Ge or Sn), and H2EEH2, (E = C, Si, Ge or Sn) and (2) the correlation of these energies with barriers for planarization or linearization. The calculations suggest an upper limit of about 12 eV energy separation of the interacting levels for SOJT effects to be significant, which is considerably larger than previously thought and implies that SOJT effects may be more common than currently realized.

3.
Inorg Chem ; 59(3): 1871-1882, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31927992

RESUMO

The synthesis, molecular structures, and spectroscopic details of a series of isocyanide and nitrile complexes of the early first-row transition-metal tris(silyl)amides M{N(SiMe3)2}3 (M = Ti, V) are reported. Previously, first-row transition-metal tris(silyl)amides were generally thought to be incapable of forming complexes with Lewis bases due to their excessive steric crowding. However, it is now shown that simple treatment of the base-free trisamides with 2 equiv of an isocyanide or nitrile base at room temperature results in the formation of the trigonal bipyramidal complexes Ti{N(SiMe3)2}3(1-AdNC)2 (1), Ti{N(SiMe3)2}3(CyNC)2 (2), Ti{N(SiMe3)2}3(ButNC)2 (3), Ti{N(SiMe3)2}3(PhCN)2 (4), V{N(SiMe3)2}3(1-AdNC)2 (5), V{N(SiMe3)2}3(CyNC)2 (6), V{N(SiMe3)2}3(ButNC)2 (7), and V{N(SiMe3)2}3(PhCN)2 (8), which incorporate two donor ligands (1-AdNC = 1-adamantyl isocyanide, CyNC = cyclohexyl isocyanide, ButNC = tert-butyl isocyanide, PhCN = benzonitrile). All complexes display a characteristic increase in the frequency of the multiple bonded C-N stretching mode which is observed to be in the range of 2170-2190 cm-1 for the isocyanide complexes 1-3 and 5-7 and at 2250 cm-1 for the nitrile complex 8. This effect was not observed for the titanium nitrile complex 4, suggesting weak binding of the donor to titanium. Paramagnetic 1H NMR studies showed these complexes to have detectable, though extremely broadened, signals attributable to the trimethylsilyl groups of the amide ligands (δ = ca. 2.8 ppm for titanium isocyanide complexes, ca. 4.5-4.7 ppm for vanadium isocyanide complexes). A variable-temperature 1H NMR study showed that in solution these complexes exist as mixtures of the five-coordinate species and a putative four-coordinate species coordinating a single Lewis basic ligand. Electronic spectroscopy indicated that the vanadium complexes 5-8 bind the Lewis bases more strongly than the corresponding titanium complexes, where the spectra of complexes 1-4 are essentially identical to the base-free Ti{N(SiMe3)2}3 at the temperatures and concentrations studied. In contrast to these results, no corresponding complexes were detected for the metal silylamides M{N(SiMe3)2}3 (M = Cr, Mn, Fe, or Co) when treated with the isocyanide or nitrile bases.

4.
J Am Chem Soc ; 142(5): 2233-2237, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31951405

RESUMO

The reaction of the molybdenum-molybdenum triple-bonded dimer (CO)2CpMo≡MoCp(CO)2 (Cp = η5-C5H5) with the triple-bonded dimetallynes AriPr4MMAriPr4 or AriPr6MMAriPr6 (AriPr4 = C6H3-2,6-(C6H3-2,6-Pri2)2, AriPr6 = C6H3-2,6-(C6H2-2,4,6-Pri3)2; M = Ge, Sn, or Pb) under mild conditions (≤80 °C, 1 bar) afforded AriPr4M≡MoCp(CO)2 or AriPr6M≡MoCp(CO)2 in moderate to excellent yields. The reactions represent the first isolable products from a metathesis of two metal-metal triple bonds. Analogous exchange reactions with the single-bonded (CO)3CpMo-MoCp(CO)3 gave ArM̈-MoCp(CO)3 (Ar = AriPr4 or AriPr6; M = Sn or Pb). The products were characterized by NMR (1H, 13C, 119Sn, or 207Pb), electronic, and IR spectroscopy and by X-ray crystallography.

5.
Inorg Chem ; 58(22): 15034-15038, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31651165

RESUMO

Herein, we report the characterization of a novel germanium hydride radical arising from the photolysis/thermolysis of the diarylgermylene GeR2 [R = terphenyl: AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2 or AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2] by using electron paramagnetic resonance spectroscopy complemented with theoretical calculations. The trapped germanium radical is a pseudoplanar S = 1/2 germanium(III) hydride, i.e., •GeHRR' (R = AriPr4 or AriPr6; R' is a quaternary carbon), with a g tensor of [2.029, 2.003, 1.990], a 73Ge hyperfine tensor of [-10, -90, -10] MHz, and a strong 1H hyperfine tensor of [-23.0, -20.5, -31.5] MHz for the hydride. The germanium(III) hydride radical is a result of the insertion of a germanium(I) radical intermediate (:GeR) in a C-H bond, due to the greater reactivity of the germanium(I) radical intermediate in comparison with the tin(I) counterpart that we trapped earlier.

6.
Chem Commun (Camb) ; 55(69): 10285-10287, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31396611

RESUMO

Simple reactions of their terphenyl lead bromide precursors with DIBAL-H in diethyl ether solution at ca. -78 °C leads to the isolation of the hydrides {Pb(µ-H)ArPri4}2 (ArPri4 = C6H3-2,6-(C6H3-2,6-Pri2)2) (1) and {Pb(µ-H)ArMe6}2 (ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2) (2) in good yield (60-80%). The isolated solids are stable at up to 5 °C for several weeks but are thermally labile in solution. Hydride 1 decomposes to the diplumbyne ArPri4PbPbArPri4, while 2 decomposes to the plumbylene Pb(ArMe6)2. The decomposition of 1 was determined to be zero order with a rate constant of ca. 2.0 × 10-5 M min-1 at 298 K.

7.
J Am Chem Soc ; 141(36): 14370-14383, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31390863

RESUMO

A series of formally triply bonded diplumbyne analogues of alkynes of the general formula ArPbPbAr (Ar = terphenyl ligand with different steric properties) was synthesized by two routes. All diplumbyne products were synthesized by a simple reduction of the corresponding Pb(II) halide precursor ArPb(Br) by DIBAL-H with yields in the range 8-48%. For one of the diplumbynes ArPri4PbPbArPri4 (ArPri4 = C6H3-2,6-(C6H3-2,6-Pri2)2) it was shown that reduction of ArPri4Pb(Br) using a magnesium(I) beta-diketiminate afforded a much improved yield in comparison (29 vs 8%) to that obtained by reduction with DIBAL-H. The more sterically crowded diplumbyne ArPri8PbPbArPri8 (ArPri8 = C6H-3,5-Pri2-2,6-(C6H2-2,4,6-Pri3)2) displayed a shortened Pb-Pb bond with a length of 3.0382(5) Å and wide Pb-Pb-C angles of 114.73(7)° and 116.02(6)° consistent with multiple-bond character with a bond order of up to 1.5. The others displayed longer metal-metal distances and narrower Pb-Pb-C angles that were consistent with a lower bond order that approached one. Computational studies of the diplumbynes yielded detailed insight of the unusual bonding and explained their similar electronic spectra arising from the flexibility of the C-Pb-Pb-C core in solution. Furthermore, the importance of London dispersion interactions for the stabilization of the diplumbynes was demonstrated.

9.
J Am Chem Soc ; 141(32): 12527-12530, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31345027

RESUMO

The tin-tin triple bond in the distannyne AriPr4SnSnAriPr4, AriPr4 = C6H3-2,6(C6H3-2,6-iPr2)2, undergoes reversible cleavage in deuterated toluene to afford two :SnAriPr4 radicals in solution as shown by 1H nuclear magnetic resonance and electron paramagnetic resonance spectroscopy. Variable temperature data afforded an enthalpy of dissociation of ΔHdiss = 17.2 ± 1.7 kcal mol-1 via van't Hoff analysis.

10.
Inorg Chem ; 58(13): 8793-8799, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31187985

RESUMO

The synthesis and spectroscopic, structural, and magnetic characterization of the quasi-linear metal(II) bis(amides) M{N(SiPr i3)Dipp}2 [Dipp = C6H3-2,6-Pr i3; M = Fe (1), Co (2), or Zn (3)] are described. The magnetic data demonstrate the impact of metal ligand π-interactions on the magnetic properties of these two-coordinate transition metal amides. Disproportionation of the copper(I) amide species featuring the ligand -N(SiPr i3)Dipp resulted in the decomposition product [(Pr i3Si)N( c-C6H2-2,6-Pr i2)]2 (4). The electron paramagnetic resonance spectrum of the unstable two-coordinate Cu{N(SiPr i3)Dipp}2 displays significantly less Cu-N bond covalency than the stable two-coordinate copper(II) species Cu{N(SiMe3)Dipp}2. The testing of -N(SiPr i3)Dipp and a range of other, related bulky amide ligands with their copper derivatives highlights the peculiar combination of steric and electronic properties of the Wigley ligand -N(SiMe3)Dipp that enable it to stabilize the unique two-coordinate copper(II) complex Cu{N(SiMe3)Dipp}2.

11.
Inorg Chem ; 58(9): 6095-6101, 2019 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-30950608

RESUMO

During the preparation of V{N(SiMe3)2}3 (1), a discrepancy between the violet color that we observed and the brown color previously reported prompted further investigation of this compound. As a result, a new spectroscopic study and a full structural characterization are presented. The synthesis, spectroscopy, and structural characteristics of its reduced salt, [K(18-crown-6)(Et2O)2][V{N(SiMe3)2}3] (2), and its chromium congener, [K(18-crown-6)(Et2O)2][Cr{N(SiMe3)2}3] (3), are also described. The 1H NMR spectra for 1-3 and Cr{N(SiMe3)2}3 as well as their cyclic voltammograms are also reported.

12.
Chem Commun (Camb) ; 55(3): 405-407, 2019 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-30542688

RESUMO

The diarylstannylenes, Sn(AriPr4)2 and Sn(AriPr6)2, (AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2, AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2), undergo a facile migratory insertion reaction with ethylene at 60 °C to afford the alkyl aryl stannylenes AriPr4SnCH2CH2AriPr4 and AriPr6SnCH2CH2AriPr6 which were characterized via1H, 13C and 119Sn NMR, UV-vis and IR spectroscopy, as well as by X-ray crystallography. Quantum mechanical calculations were performed, and two potential mechanisms were identified, with a migratory insertion reaction pathyway being energetically preferred.

13.
J Am Chem Soc ; 140(41): 13195-13199, 2018 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-30269488

RESUMO

[Ar'SnCo]2 (1, Ar' = C6H3-2,6{C6H3-2,6- iPr2}2), a rare metal-metal bonded cobalt-tin cluster with low-coordinate tin atoms, was prepared by the reaction of [K(thf)0.2][Co(1,5-cod)2] (cod = 1,5-cyclooctadiene) with [Ar'Sn(µ-Cl)]2. This reaction illustrates a promising synthetic strategy to access uncommon metal clusters. The structure of 1 features a rhomboidal Co2Sn2 core with strong metal-metal bonds between tin and cobalt and a weaker tin-tin interaction. Reaction of 1 with white phosphorus afforded [Ar'2Sn2Co2P4] (2), the first molecular cluster compound containing phosphorus, cobalt and tin.

14.
Inorg Chem ; 57(11): 6491-6502, 2018 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-29745653

RESUMO

The first-row transition-metal(II) dithiolates M(SAriPr4)2 [AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2; M = Cr (1), Mn (3), Fe (4), Co (5), Ni (6), and Zn (7)] and Cr(SArMe6)2 [2; ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2] and the ligand-transfer reagent (NaSAriPr4)2 (8) are described. In contrast to their M(SAriPr6)2 (M = Cr, Mn, Fe, Co, Ni, and Zn; AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2) congeners, which differ from 1 and 3-6 in having p-isopropyl groups on the flanking aryl rings of the terphenyl substituents, compounds 1 and 4-6 display highly bent coordination geometries with S-M-S angles of 109.802(2)° (1), 120.2828(3)° (4), 91.730(3)° (5), and 92.68(2)° (6) as well as relatively close metal-flanking aryl ring η6 interactions with metal-centroid distances of 2.11477(6) Å (1), 1.97188(3) Å (2), 2.15269(6) Å (4), 1.62058(9) Å (5), and 1.724(8) Å (6). However, the d5 (Mn) and d10 (Zn) complexes 3 and 7 display linear or near-linear coordination with no close metal-ligand distances. The nonlinear geometries of 1 and 4-6 also contrast with those of their AriPr4-substituted alkoxo and amido congeners, which have strictly linear coordination. Complexes 1-7 were synthesized by the reaction of the lithium or sodium thiolate salt with the metal dihalide or, in the case of 3, by the reaction of the thiol with the amido complex Mn[N(SiMe3)2]2. All compounds were characterized by electronic spectroscopy, X-ray crystallography, and magnetic measurements using Evans' method and SQUID magnetometry. It was concluded that, despite the large bulk of the AriPr4 substituents, the absence of p-isopropyl groups on the flanking rings of the ligand permits close secondary metal-flanking ring distances. The compounds are characterized by more intense colors and display magnetic moments that are generally lower than the spin-only values, in agreement with the covalent character of the close metal-flanking ring η6 interactions.

15.
J Am Chem Soc ; 140(17): 5674-5677, 2018 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-29648820

RESUMO

The diarylstannylene, :Sn(Ar iPr4)2 (Ar iPr4 = C6H3-2,6-(C6H3-2,6- iPr2)2), undergoes C-H metathesis with toluene, m-xylene, or mesitylene in solutions of these solvents at 80 °C. The products, [Ar iPr4Sn(CH2Ar)]2 (Aryl=C6H5 (1a), C6H4-3-Me (1b), C6H3-3,5-Me2(1c)) were characterized via 1H, 13C and 119Sn NMR, UV-vis and IR spectroscopy, and by X-ray crystallography for 1a and 1b. A stoichiometric amount of the arene, Ar iPr4H, was also produced in these reactions. The use of EPR spectroscopy indicated the presence of a new type of one-coordinate, tin-centered radical, :SnAr iPr4, resulting from Sn-C bond cleavage in Sn(Ar iPr4)2.

16.
J Am Chem Soc ; 140(2): 590-593, 2018 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-29272120

RESUMO

The terphenyl tin(II) hydride [AriPr4Sn(µ-H)]2 (1) (AriPr4 = C6H3-2,6(C6H3-2,6-iPr2)2) was shown to form an equilibrium with the distannyne AriPr4SnSnAriPr4 (2) and H2 in toluene at 80 °C. The equilibrium constant and Gibbs free energy for the dissociation of H2 are 2.23 × 10-4 ± 4.9% and 5.89 kcal/mol ± 0.68%, respectively, by 1H NMR spectroscopy and 2.33 × 10-4 ± 6.2% and 5.86 kcal/mol ± 0.73%, respectively, by UV-vis spectroscopy, indicating that the hydride 1 is strongly favored. Further heating of 2 at ca. 100 °C afforded the known pentagonal-bipyramidal Sn7 cluster Sn5(SnAriPr4)2 (3). Mechanistic studies show that 3 is formed from distannyne 2, which is generated from 1. The order of the reaction for the conversion of 2 into 3 was found to be zero, and the rate constant is 1.77 × 10-5 M s-1 at 100 °C. Hydride 1 was further characterized by cyclic voltammetry, and its pKa was found to be 18.8(2) via titration with 1,8-diazabicyclo[5.4.0]undec-7-ene. The bond dissociation free energy was estimated to be 51.1 kcal/mol ± 3.4% on the basis of its pKa and reduction potential. Studies with deuterium indicate ready exchange of D2 with the hydrides in 1.

17.
J Am Chem Soc ; 139(49): 17723-17726, 2017 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-29185742

RESUMO

Complex Fe(bpyB)3 (1, bpyB = 5,5'-bis(dimesitylboranyl)-2,2'-bipyridine) and its reduced species [(18-c-6)K(THF)2]·[Fe(bpyB)3] (2) were synthesized. Their solid state and electronic structures were investigated by single crystal X-ray crystallography, electron paramagnetic resonance and UV-vis spectroscopy, and SQUID measurements. In 1 two bpyB radical anions are fused by a diamagnetic FeII ion, whereas in 2 all three bpyB ligands are in the radical state. Complex 1 possesses an open-shell singlet ground state with a singlet-triplet gap of 0.18 kcal mol-1 and 2 features an open-shell doublet ground state with a doublet-quartet gap of 1.4 kcal mol-1, as determined by SQUID measurements. The unpaired-electrons in 1 and 2 mainly delocalize over the boron atoms and the bipyrdine moieties with negligible spin density at the iron center. Complex 2 represents the first isolable example of boron-based triradicals.

18.
Inorg Chem ; 56(23): 14596-14604, 2017 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-29130691

RESUMO

A simple exchange reaction between [AriPr4Sn(µ-Cl)]2 (1) and sodium azide afforded the doubly bridged Sn(II) azide, [AriPr4Sn(µ-N3)]2 (2) (AriPr4 = C6H3-2,6(C6H3-2,6-iPr2)2) in 85% yield. Photolysis of a diethyl ether solution of 2 for ca. 16 h yielded an azepinyl-substituted insertion product, [C6H3-2-(C6H3-2,6-iPr2)-6-(C6H3N-3,7-iPr2)Sn]2 (3). The reaction of the Lewis acid, B(C6F5)3 (BCF), or the Lewis base, pyridine, with 2 dissociates the dimer to afford the corresponding complexed monomeric Sn(II) azide, AriPr4SnN3BCF (4) in which BCF coordinates the α-nitrogen, or AriPr4Sn(pyridine)N3 (6) in which pyridine coordinates to the tin atom. Photolysis of 4 in diethyl ether for 12 h results in the insertion of the α-nitrogen of the azide group into one of the B-C bonds of the BCF acceptor to yield the tin(II) amide, AriPr4SnN(C6F5)B(C6F5)2 (5). In contrast, photolysis of 6 for over 36 h afforded no apparent reaction. A highly reactive Sn nitride intermediate, AriPr4Sn≡N, is proposed as part of the mechanistic pathway for the formation of 3 and 5 as a result of trapping the tin-centered radical isomers. This was effected by immediate freezing the samples of 2 or 4 after ca. 30 min of UV photolysis and recording their electron paramagnetic resonance spectra. These exhibited a rhombic g tensor of [g1, g2, g3] = [2.029, 1.978, 1.933]. This radical intermediate could be related to the valence isomers of the nitride [-SnIV≡N] intermediate, in isomeric equilibrium with the nitrene [-SnII-N] and nitridyl [-SnIII═N·] forms, but with the spin density on the nitrogen being quenched, possibly by the H atom abstraction to form an S = 1/2 species of formula -Sn·â•N(H).

19.
Inorg Chem ; 56(16): 9892-9902, 2017 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-28758744

RESUMO

The binding constants of several monodentate Lewis bases (L) having different donor atoms [L = tetrahydrofuran (THF), tetrahydrothiophene (THT), pyridine, 4-(dimethylamino)pyridine (DMAP), PMe3, PCy3, and 1,3-bis(1,3,5-trimethylphenyl)imidazol-2-ylidene (IMes)] to the linear two-coordinate bis(amido) transition-metal complexes, M{N(SiMe3)Dipp}2 [M = Fe (1), Co (2), and Ni (3)] were determined by electronic absorption spectroscopy. In addition, 1H NMR spectroscopy was used to study the complexation of M{N(SiMe3)Dipp}2 by THF. The binding constants of the less bulky amido complexes [M{N(SiMe3)2}2]2 (M = Fe or Co; the nickel species is unstable) were also measured and found to bind THF 102-103 times more strongly than M{N(SiMe3)Dipp}2. Furthermore, unlike the corresponding -N(SiMe3)Dipp complexes, where the iron species are more strongly complexed than those of cobalt, the --N(SiMe3)2 species [Co{N(SiMe3)2}2]2 displayed a higher binding constant to THF than [Fe{N(SiMe3)2}2]2, which is in agreement with the stronger association of the [Co{N(SiMe3)2}2]2 dimer in comparison to that of its iron analogue. The binding strengths of the ligands to 1-3 were found to be in the order of DMAP > pyridine > PMe3 > PCy3 ≈ IMes > THF > THT, and those of the respective metals were in the order of Fe > Co > Ni.

20.
J Am Chem Soc ; 139(34): 12069-12075, 2017 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-28787134

RESUMO

Chemical oxidations of piano-stool chromium/cobalt carbonyl complexes Cr(CO)3(η6,η5-C6H5C5H4)Co(CO)2 (1) and Cr(CO)3(η6,η6-C6H5C6H5) Cr(CO)3 (2) were investigated. Upon one-electron oxidation, 1 was transformed to a heterometalloradical species, 1•+. However, either one- or two-electron oxidation of 2 afforded a decomposition product, 3. Dipping 3 into pentane led to the formation of 4 via a crystal-to-crystyal transformation with the removal of solvent molecules. Complexes 1•+ and 4 were fully characterized by various spectroscopic techniques and single-crystal X-ray analysis. Cation 1•+ features a weak Cr-Co bond with a Wiberg bond order of 0.278. A near-infrared absorption band around 1031 nm was observed for 1•+, which is far red-shifted in comparison to previously reported dinuclear metalloradical species. Complex 4 contains a chromium(II) with a distorted pyramidal geometry and displays single-molecule magnetic properties.

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