Primary Amines RNH2 Research Articles

The CF3 Group as a Synthon of the CF+ Unit in Palladium Chemistry.

The homoleptic trifluoromethyl-palladium(II) complex [Pd(CF3)4]2- (1) is shown to be highly active towards amines. Thus, when treated with primary amines RNH2, it readily undergoes aminolysis of one of the CF3 ligands affording the isocyanide complexes [(CF3)3Pd(CNR)]- (R=aryl). In this process the original CF3 group undergoes total defluorination. Interestingly, the reaction of 1 with secondary amines R2NH proceeds with loss of just two F-substituents, whereby the Fischer-type fluoroaminocarbene complexes [(CF3)3Pd(CFNR2)]- are formed (R=Et, Ph). The reaction of 1 with diamines affords different [(CF3)3Pd(NHC)]- complexes containing sterically non-demanding NHC ligands. Representative examples of various topologies are reported based on the common imidazolidin-2-ylidene or benzimidazolin-2-ylidene rings as well as the expanded-ring perimidin-2-ylidene. This metal-tailored synthetic route, where a CF3 group acts as a pre-carbenic unit, is unprecedented in the vast NHC-chemistry. It takes place under very mild conditions and is envisaged to be extensible to other non-isolable NHC ligands. The key difluorocarbene intermediate [(CF3)3Pd(CF2)]- is experimentally detected.

The CF3 Group as a Synthon of the CF+ Unit in Palladium Chemistry

AbstractThe homoleptic trifluoromethyl‐palladium(II) complex [Pd(CF3)4]2− (1) is shown to be highly active towards amines. Thus, when treated with primary amines RNH2, it readily undergoes aminolysis of one of the CF3 ligands affording the isocyanide complexes [(CF3)3Pd(CNR)]− (R=aryl). In this process the original CF3 group undergoes total defluorination. Interestingly, the reaction of 1 with secondary amines R2NH proceeds with loss of just two F‐substituents, whereby the Fischer‐type fluoroaminocarbene complexes [(CF3)3Pd(CFNR2)]− are formed (R=Et, Ph). The reaction of 1 with diamines affords different [(CF3)3Pd(NHC)]− complexes containing sterically non‐demanding NHC ligands. Representative examples of various topologies are reported based on the common imidazolidin‐2‐ylidene or benzimidazolin‐2‐ylidene rings as well as the expanded‐ring perimidin‐2‐ylidene. This metal‐tailored synthetic route, where a CF3 group acts as a pre‐carbenic unit, is unprecedented in the vast NHC‐chemistry. It takes place under very mild conditions and is envisaged to be extensible to other non‐isolable NHC ligands. The key difluorocarbene intermediate [(CF3)3Pd(CF2)]− is experimentally detected.

Nucleophilic Reactivity at a ═CH Arm of a Lutidine-Based CNC/Rh System: Unusual Alkyne and CO2 Activation.

Reaction of an amido pincer complex [(CNC)*Rh(CO)] (1) (CNC* is the deprotonated form of CNC) with carbon dioxide gave a neutral complex [(CNC-CO2)Mes*Rh(CO)] (2), which is the result of a C-C bond-forming reaction between the deprotonated arm of the CNC* ligand and CO2. The molecular structure of 2 showed a zwitterionic complex, where the CO2 moiety is covalently connected to the former ═CH arm of the CNC* pincer ligand. The unusual structure of 1 allowed us to explore the reactivity of the CO2 moiety with selected primary amines RNH2 (benzylamine and ammonia), which afforded cationic complexes [(CNC)MesRh(CO)][HRNC(O)O] (R = Bz (3), H (4)). Compounds 3 and 4 are the result of a C-N coupling between the incoming amine and the CO2 fragment covalently connected to the pincer ligand in 2, a process that involves protonation of the "CH-CO2" fragment in 2 from the respective amines. Once revealed the nucleophilic character of the ═CH fragment in 1, we explored its reactivity with alkynes, a study that enlightened a novel reactivity trend in alkyne activation. Reaction of 1 with terminal alkynes RC≡CH (R = Ph, 2-py, 4-C6H4-CF3) yielded neutral complexes [(CNC-CH═CHR)Mes*Rh(CO)] (R = Ph (5), 2-py (6), 4-C6H4-CF3 (7)) in good yields. Deuterium labeling experiments with PhC≡CD confirmed that complex 5 is the product of a formal insertion of the alkyne into the C(sp2)-H bond of the deprotonated arm in 1. This structural proposal was further confirmed by the X-ray molecular structure of phenyl complex 5, which showed the alkyne covalently linked to the pincer ligand. Besides, this novel transformation was analyzed by DFT methods and showed a metal-ligand cooperative mechanism, based on the initial electrophilic attack of the alkyne to the ═CH arm of the CNCMes* ligand (making a new C-C bond) followed by the action of a protic base (HN(SiMe3)2), which is able to perform a proton rearrangement that leads to the final product 5.

Investigations on the synthesis, structural characterization and electrochemical properties of diiron azadithiolate complexes and phosphine-substituted derivatives

Three novel diiron azadithiolate complexes Fe2[(μ-SCH2)2NCH2CH2CH(CH3)2](CO)6 (1), Fe2[(μ-SCH2)2NCH(CH2CH3)2](CO)6 (2) and Fe2[(μ-SCH2)2NCH2CH2CH2SCH3](CO)6 (3) have been synthesized by treatment of Fe2(μ-SCH2OH)2(CO)6 with primary amines RNH2 (R=CH2CH2CH(CH3)2, CH(CH2CH3)2, CH2CH2CH2SCH3). Meanwhile, reaction of Fe2(μ-SCH2OH)2(CO)6 and diphosphine ligand Ph2PCH2PPh2 (dppm), followed by the addition of amines NH2CH2CH2CH(CH3)2 and NH2CH(CH2CH3)2 resulted in the formation of the target phosphine-substituted diiron azadithiolate complexes Fe2[(μ-SCH2)2NCH2CH2CH(CH3)2](CO)5(dppm) (4) and Fe2[(μ-SCH2)2NCH(CH2CH3)2](CO)5(dppm) (5). Complexes 1–5 have been fully characterized by elemental analysis, FTIR, and NMR (1H, 13C, 31P) spectroscopies, and particularly for 1–3 by X-ray crystallography. In addition, complexes 1–5 were found to be catalysts for hydrogen production under electrochemical conditions.

η3-Silaallyl/Alkenylsilyl Molybdenum Complex: Synthesis, Structure, and Reactivity toward Primary Amines To Form Mo–N–Si Three-Membered Cyclic Complexes

The new η3-silaallyl/alkenylsilyl molybdenum complex Cp*Mo(CO)2(η3-Ph2SiCHCMe2) (3) was synthesized by the reaction of Cp*Mo(CO)2(py)Me with Ph2HSiCH═CMe2. Reactions of 3 with primary amines RNH2 (R = tBu, iPr, Et) gave Mo–N–Si three-membered cyclic complexes Cp*Mo(CO)2(κ2-N,Si-RHNSiPh2) (5a, R = tBu; 5b, R = iPr; 5c, R = Et) with elimination of isobutene. In NMR tube reactions using iPrNH2 and EtNH2, the Mo–N–Si–C four-membered cyclic complexes Cp*Mo(CO)2(κ2-N,C-RHNSiPh2CHiPr) (4b, R = iPr; 4c, R = Et) were observed as intermediates leading to 5b and 5c, respectively. Complex 4c was successfully isolated in a preparative reaction. The molecular structures of 3, 4c, and 5b were determined by X-ray crystal analyses. Interestingly, the contribution of silylene character was suggested for the SiPh2 moiety of 5b from the X-ray structure. The reaction of 5b with MeOH gave the dinuclear complex Cp*(CO)2Mo(μ-OMe)(μ-H)Mo(CO)2Cp* as a major product.

Novel aspects of the transamination reaction between Ti(NMe2)4 and primary amines

A detailed study of the transamination reaction between Ti(NMe2)4 and primary amines RNH2 is reported Alkylamines (1-adamantylamine, t-butylamine) and triphenylsilylamine yield dimers of the type [Ti(μ-NR)(NMe2)2]2 (R = 1-adamantyl (1), (t)Bu (2), SiPh3 (3)). The experimental conditions and the nature of the amine are important issues that determine the scope and yield of the reaction. When reacted under the same conditions, aniline PhNH2 does not yield the expected dimer, but instead the trimer [Ti3(μ(2)-NPh)3(μ(3)-NPh)(NMe2)4(NHMe2)] (5) and tetramer [Ti4(μ-NPh)5(NMe2)6] (6) complexes were characterized. The reaction of Ti(NMe2)4 and 2,6-diisopropylaniline (Ar*NH2) is essentially an equilibrium reaction of great complexity in which multiple species can coexist in solution. However, under certain circumstances, we were able to isolate and/or characterize several new complexes such as [Ti(μ-NAr*)(NMe2)2]2 (7), [(Me2N)2Ti(μ-NAr*)2Ti(NMe2)(NHAr*)] (8), [Ti(NMe2)3]2(μ-NAr*) (9), [(Ar*NH)2Ti(μ-NAr*)2Ti(NMe2)2] (10), [(Me2N)(Me2NH)Ti(μ-NAr*)2Ti(NMe2)(=NAr*)] (11), Ti(NHAr*)4 (12), and [(Ar*NH)2Ti(μ-NAr*)2Ti(NMe2)(NHAr*)] (13). Complexes 8 and 11 are tautomers. Alternatively, complex 7 was prepared by deprotonation of NHMe2 ligands in Ti(=NAr*)Cl2(NHMe2)2 with KN(SiMe3)2. Addition of pyridine (py) to the reaction of Ti(NMe2)4/Ar*NH2 mixtures or to 7 or 8 allows characterization of transient [Ti(μ-NAr*)(NMe2)2]2·py (14) and trapping of the intermediates [(Me2N)(py)2Ti(μ-NAr*)2Ti(NMe2)(=NAr*)] (15), Ti(=NAr*)(NHAr*)(NMe2)(py)2 (16), and Ti(=NAr*)(NHAr*)2(py)2 (17). The crystal structures of 15 compounds were determined by X-ray diffraction studies.

Reactions of nucleophilic addition of primary amines to the nitrilium derivative of the closo-decaborate anion [2-B10H9(N≡CCH3)

Compounds (Bu4N)[2-B10H9{NH=C(NHR)CH3}]− are obtained by reactions of the tetrabutylammonium salt of the [2-B10H9(N≡CCH3)]− anion with aliphatic and aromatic primary amines RNH2 (R = n-C3H7, n-C4H9, cyclo-C5H9, C6H5, cyclo-C6H11, n-C6H13, C7H7, C8H8NH2, C6H4NO2, and C18H37) and identified by IR, ESI/MS, and NMR (1H, 11B, and 13C) spectroscopy. The structures of the amidine-type derivatives [2-B10H9{Z-NH=C(NH-cyclo-C5H9)CH3}]− and [2-B10H9{Z-NH=C(NH-C7H7)CH3}]− are determined by X-ray diffraction.

Efficient synthesis of new 1-[Alkyl(aryl)]-5-(3,3,3-trihalo-2-oxopropylidene)pyrrolidin-2-ones

Reactions of methyl 4-methoxy-6-oxo-7,7,7-trihalo-4-heptenoates 1 and 2 with primary amines RNH2, where R = PhCH2, PhCH2CH2, Ph, 4-MeC6H4, 4-MeOC6H4, 4-ClC6H4, 4-BrC6H4, 2-pyridyl, 5-methyl-3-isoxazolyl, 4-NH2C6H4 affording methyl 4-[alkyl(aryl)amino]-6-oxo-7,7,7-trihalo-4-heptenoates 3, 4, in good yields (57-95%), which suffer quantitative intramolecular cyclocondensation to produce 1-alkyl(aryl)-5-(2-oxo-3,3,3-trihalopropylidene)pyrrolidin-2-ones 5, 6, are reported. The structures of the isolated new products were assigned by means of ¹H,13C NMR measurements and mass spectrometry. The Z and E configuration of compounds 3d and 5b respectively were established from X-ray crystallography.

New Efficient Synthesis of 2‐Substituted Benzothieno[3,2‐d]pyrimidin‐4(3H)‐ones via a Tandem Aza‐Wittig Reaction.

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New Efficient Synthesis of 2-Substituted Benzothieno[3,2-d]pyrimidin-4(3H)-ones via a Tandem Aza-Wittig Reaction

1-Aryl-3-[2-(ethoxycarbonyl)benzothien-3-yl]carbodiimides 4, obtained from aza-Wittig reactions of iminophosphorane 3 with aryl isocyanates, reacted with secondary amines, phenols, or alkanols in the presence of a catalytic amount of potassium carbonate or sodium alkoxide to give 2-substituted benzothieno[3,2-d]pyrimidin-4(3H)-ones 6 in good yields. The reaction of carbodiimides 4 with primary amines RNH2 (R ≠ H, Me) in the presence of sodium ethoxide selectively produced one regioisomer 8 via a base-catalyzed cyclization mechanism. However, a different regioisomer 9 was obtained when primary amines RNH2 (R = H, Me) were used in the absence of sodium ethoxide via a direct cyclization mechanism.

Reaction of 1,2-dibromoethane with primary amines: formation of N,N′-disubstituted ethylenediamines RNH–CH2CH2–NHR and homologous polyamines RNH–[CH2CH2NR]n–H

The reaction of primary amines RNH2 (R: Me, Et, iPr, tBu and Ph) with 1,2-dibromoethane gave N,N′-disubstituted ethylenediamines R–NH–CH2CH2–NH–R (1) in yields ranging from 10% (1a; R=Me) to 70% (1d, R=tBu; 1e, R=Ph). Piperazines and N-substituted polyethyleneimines were identified (1H NMR, 13C NMR and EI-MS) as side products of the reaction and isolated by fractional distillation. The piperazines 2 are formed in yields of 3–10% and can be separated from the diamines 1 in all cases, except for R=Me and Ph. The polyamine homologues RNH–[CH2CH2NR]n–H (3–5) were isolated in yields ranging from 0.1% (n=4, R=iPr) to 14% (n=2, R=iPr). The yields of 1 increase with the size of the substituent R, no obvious trend exists for the yields of the side products.

Perfluoroalkyl-substituted triazapentadienes and their metal complexes.

Triazapentadienides, C(3)F(7)-C(=NR)-N=C(NHR)-C(3)F(7), result from the reaction of primary amines RNH(2) with the fluorinated imine C(3)F(7)-CF=N-C(4)F(9). The aniline derivative (R = Ph) is a weak monoprotic acid in dmso. Its conjugate base exhibits an extensive coordination chemistry. It acts as a bidentate ligand toward the molecular fragments Pd(C(3)H(5)), Rh(c-C(8)H(12)), Ir(c-C(8)H(12)), and Rh(CO)(2). The chelates [C(3)F(7)-C(NPh)-N-C(NPh)-C(3)F(7)](2)M, M = Mg, Mn, Fe, Co, Ni, Cu, Zn, and Pd, were prepared. In the crystallographically characterized Co complex, the metal is 3d(7), S = (3)/(2) and tetrahedrally coordinated. Spin densities at carbon in the C(6)H(5) and C(3)F(7) groups were estimated from the (1)H and (19)F contact shifts. Spin delocalization onto phenyl sp(2) carbons is approximately 10 times greater than onto the fluorinated sp(3) carbons.

Iron carbonyl sulfides, formaldehyde, and amines condense to give the proposed azadithiolate cofactor of the Fe-only hydrogenases.

The azadithiolate (SCH2NHCH2S) cofactor proposed to occur in the Fe-only hydrogenases forms efficiently by the condensation of Fe2(SH)2(CO)6 (1), formaldehyde, and ammonia (as (NH4)2CO3). The resulting Fe2[(SCH2)2NH](CO)6 reacts with Et4NCN to give (Et4N)2[Fe2[(SCH2)2NH](CO)4(CN)2], for which crystallographic characterization confirmed an axial N-H and an elongated C-S bond of 1.858(3) A. Primary amines RNH2 (R = Ph, t-Bu) also participate in the condensation reaction, and Fe3S2(CO)9 can be employed in place of 1. Mechanistically, the Fe2[(SCH2)2NH] moiety is shown to arise via two pathways: (i) via the intermediacy of Fe2[(SCH2OH)2](CO)6, which was detected and shown to react with amines, and (ii) via the reaction of 1 with cyclic imines (CH2)3(NR)3 (R = Ph, Me). The reaction of 1 with (CH2)6N4 (hexamethylenetetramine) gives Fe2[(SCH2)2NH](CO)6. Trace amounts of Fe2[(SCH2)2N-t-Bu](CO)6 arise via the reaction of aqueous FeSO4, formaldehyde, NaSH, and t-BuNH2 under an atmosphere of CO.

Dehydrocoupling reactions of amines with silanes catalyzed by [(Et 2N) 3U][BPh 4

Dehydrocoupling reactions of primary amines RNH 2 with PhSiH 3 were catalyzed by [(Et 2N) 3U][BPh 4] to give the corresponding aminosilanes PhSiH 3− n (NHR) n ( n=1–3), the relative yields of the products were found to be dependent on the experimental conditions and on the nature of R. For a primary silane (PhSiH 3), the reactivity of RNH 2 follows the order primary>secondary>tertiary. Similar dehydrocoupling reactions using secondary amines with secondary silanes were found to be less reactive. Homodehydrocoupling of the silane was found not to be a competing reaction at room temperature. The hydride [(RNH) 2UH][BPh 4], which is plausibly formed in the reaction of [(RNH) 3U][BPh 4] with PhSiH 3 is a likely intermediate in the catalytic cycle.

Transformation of Dimetallacyclopentanes into β-Substituted Enamine-, Alkylidene-, and α,β-Unsaturated Acyl-Bridged Diiron Complexes

Nucleophilic addition of primary amines RNH2 to C-beta of the diiron allenyl complex [Fe-2(CO)(6)(mu-PPh2)(mu-eta(1):eta(2)-(H)C=C=CH2)] (1) affords the zwitterionic dimetallacyclopentane derivatives [Fe-2(CO)(6)(mu-PPh2)(mu-eta(1):eta(1)-H2C-C(NHR)-CH2)] (R = Pr-i (2a), CH2Ph (2b), C6H11 (2c), Pr-n (2d)). In refluxing toluene, 2a-d rearrange to give the nitrogen-coordinated organodiiron alpha,beta-unsaturated amines [Fe-2(CO)(5)(mu-PPh2)(mu-eta(1)(C):eta(2)(C):eta(1)(N)-(H)C=CCH3(NHR))] (R Pr-i (3a), CH2Ph (3b), C6H11 (3c), Pr-n 3d)) via loss of carbon monoxide, a 1,3-hydrogen migration, and coordination of the beta-amino group. The bridging hydrocarbon in 3a-d adopts a highly unusual exo conformation with respect to the phosphido ligand. Compounds 3a-d are the first diiron beta-substituted enamine complexes to be isolated and structurally characterized. Such compounds have previously been proposed as short-lived intermediates which readily isomerize to their alkylidene-bridged counterparts. Complexes 3a and 3c react with trimethyl phosphite to afford the stable alkylidene valence isomers [Fe-2(CI)(5)(P(OMe)(3))(mu-PPh2)(mu-CHC(CH3)(NHR))] (R = Pr-i (4a), C6H11 (4C)). In contrast, in refluxing toluene, 2a-b react with trimethyl phosphite to give the alpha,beta-unsaturated bridging acyl complexes [Fe-2(CO)(5)(P(OMe)(3))(mu-PPh2)(mu-O=C-CH=CMe(NHR))] (R = P-i (5a), CH2Ph (5b)), which probably result from the formal insertion of carbon monoxide into an alkylidene intermediate. Single-crystal X-ray analyses of 5a and 5b showed the position of substitution to be the iron atom sigma-bonded to the acyl oxygen, trans to the phosphido bridge in 5a and trans to the iron-iron bond in 5b. Variable-temperature (31)p(H-1) and P-31-P-31 2D exchange NMR studies have been.used to examine an exchange process that equilibrates two isomers of 4a and 5b, which differ in the position of the trimethyl phosphite. At low temperature, 4a exists as a 4:1 mixture of these two substitutional isomers, while at room temperature they are in fast exchange, on the NMR time scale. The free energy of activation associated with this exchange (Delta G(273)(double dagger) = 9.5 kcal mol(-1), 4a; Delta G(273 =)(double dagger) 10.4 kcal mol(-1), 5b) is fully consistent with a restricted trigonal twist at the phosphite-substituted iron center. This exchange process also appears to be common to the alkylidene derivative 5b, which has similar (31)p(H-1) line broadening characteristics and free energy of activation. Full structural details of compounds 2a, 3a, 4c, 5a, and 5b are reported.

Syntheses and molecular structures of 2- [1′- N-(alkyl)imino-2′,2′,2′-trifluoroethyl] phenols

N-(Alkyl)imino derivatives of trifluoroacetyl phenol of the general formula 1,2-C 6H 4[C(=NR)CF 3] [OH] (R = H, 3a; Me, 3b; nPr, 3c; iPr, 3d; CH 2CH 2NH 2, 3e; CH 2CH 2CH 2NH 2, 3f; CH 2CH 2CH 2CH 2NH 2, 3g; CH 2CH 2OH, 3h; CH 2CH 2NMe 2, 3i) were synthesized from 2- trifluoroacetyl phenol and the corresponding primary amines RNH 2. The molecular structures of 3b [monoclinic, P2 1/ n, a = 6.641(3), b= 18.044(8), c = 7.716(3) Å, β = 99.95(4)°], 3d [orthorhombic, P2 12 12 1, a = 7.784(2), b = 9.291(2), c = 15.942(4) Å] and 3i [mono- clinic, P2 1/ n, a = 8.660(2), b = 18.135(2), c = 13.300(2) Å, β = 99.83 (2)°] were determined. In the solid state, 3b, 3d and 3i exist exclusively as E isomers with intermolecular hydrogen bridges, whereas according to the 1H and 19F NMR spectra in chloroform solution, compounds 3b, 3c and 3d isomerize to give a mixture of 66% Z and 34% E isomers.

Organic Syntheses via Transition Metal Complexes. 83.1 cis-1-Metalla-1,3,5-hexatrienes (Butadienylcarbene Complexes) of Tungsten via Ring Opening of Pyranylidene Complexes

Aminolysis of the 2H-pyran-2-ylidenetungsten complex 3 affords amino-1-tungsta-1,3,5-hexatrienes with different structures, depending on the reaction temperature and the type of amine involved. Addition of primary amines RNH2 (4a−d) (R = allyl, n-Bu, CH2Ph, i-Pr) to 3 at −15 °C yields salt-type (3Z)-6-amino-1-tungsta-1,3,5-hexatrienes 5a−d by reversible ring opening of the pyranylidene ring. Addition of 4a−c at 20 °C affords (3Z)-2-amino-1-tungsta-1,3,5-hexatrienes 6a−c by an irreversible ring opening of the pyranylidene ring. Secondary amines RR1NH 8a−c [RR1N = Me2N, 2-(hydroxymethyl)pyrrolidine, pyrrolidine] undergo an irreversible ring opening to 2-amino-1-tungsta-1,3,5-hexatrienes 9a−c. Aminolysis of 3 in the presence of Me3SiCl/Et3N affords acetimino pyranylidene complexes 10, from which (3Z)-2,6-diamino-1-tungsta-1,3,5-hexatrienes 11 are derived upon aminolysis. Thermolysis of 6a in THF/pyridine affords the captodative 1-amino-1,3-hexadien-5-one 12. 2H-Pyran-2-ylidene complex 3, C19H12O7W, was characterized by X-ray diffraction.

Syntheses, Structures, and Reactivity of a Series of (Pentamethylcyclopentadienyl)molybdenum(V) and -tungsten(V) Imido Complexes

Reactions of the (pentamethylcyclopentadienyl)molybdenum(V) and -tungsten(V) tetrachlorides (η5-C5Me5)MCl4 (M = Mo, W) with the primary amines RNH2 (R = t-Bu, i-Pr, C6F5, and 2,6-(i-Pr)2C6H3) lead to the formation of the imido complexes [(η5-C5Me5)M(NR)Cl2] (3a−h). X-ray structure analyses of 3a, 3c, and 3e reveal their monomeric nature. 3c and 3e crystallize in the monoclinic space group P21/c with the lattice parameters a = 15.171(3) A, b = 7.615(2) A, c = 14.758(3) A, β = 90.29(3)°, and V = 1704.9(7) A3 for 3e and a = 10.4502(7) A, b = 10.6897(8) A, c = 15.915(2) A, β = 94.342(8)°, and V = 1772.7(3) A3 for 3c. 3a crystallizes in the orthorhombic space group P212121 with a = 8.6040(10) A, b = 12.0490(10) A, c = 17.020(2) A, and V = 1764.5(3) A3. The metal−nitrogen distances of these 17-electron complexes (1.719(3) A for 3a, 1.716(12) A for 3e, and 1.748(2) A for 3c) correspond to a triple bond. (η5-C5Me5)W(NC6F5)Cl2 (3g) decomposes in the presence of air to the half-sandwich tungsten(VI) imido complex (...

Unsaturated nitrogen compounds containing fluorine. Part 9 [1]. The preparation of 2,5-dichloro-l,l,l,6,6,6-hexafluoro-3,4-diazahexa-2,4-diene and its reaction with amines

2,5-Dichloro-1,1,1,6,6,6-hexafluoro-3,4-diazahexa-2,4-diene ( 1) has been prepared in goodyield (60%) by the reaction of 1,2-bis(trifluoroacetyl)hydrazine with a mixture of N,N-dimethylaniline hydrochloride and phosphoryl chloride. Nucleophilic displacement ofchlorine from azine 1 occurs readily on reaction with primary amines RNH 2 (RPr i, Bu s,Ph, 4-FC 6H 4, 2,6-Cl 2C 5H 2NCH 2-4) and with secondary amines (morpholine and Et 2NH);in general, mono- or di-substitution can be achieved by varying the azine/amine ratio(1:2 or 1:4). The products are the azines CF 3(NRR′)NNCClCF 3 ( 7) (RH, R′Pr i;RR′Et) and CF 3C(NRR′)NNC(NRR′)CF 3 ( 8) (RH, R′=Pr i, Bu s and 2,6-Cl 2pyCH 2-4; RR′: Et; RR′CH 2CH 2OCH 2CH 2) and the imidoyl tautomersPhNC(CF 3)NHNCClCF 3 ( 9a) and ArNC(CF 3)NHNHC(CF 3)NAr ( 110) (ArPh and4-FC 6H 4). On heating at temperatures up to 120 °C, the compounds 10a (ArPh), 10b(Ar4-FC 6H 4) and 9a undergo cyclisation (with elimination of ArNH 2 or HCl) to affordthe corresponding 4-aryl-4 H-1,2,4-triazoles ( 22); the azine 8a (R=Pr i) does not cycliseunder these conditions. The azine 7a (RH, R′Pr i) on hydrolysis (NaOH/EtOH thenH 3O +) gives the trifluoroacetylhydrazine Pr iNC(CF 3)NHNHCOCF 3 ( 20) in excellent yield(92%).

Cyclische Schwefeldiimide des Siliciums. 15N-NMR-Spektroskopie und die Röntgenstrukturanalyse des Achtrings tBu2Si(NSN)2SitBu2 / Cyclic Sulfur Diimides of Silicon. 15N NMR Spectroscopy and the X-Ray Analysis of the Eight-Membered Ring tBu2Si(NSN)2SitBu2

Various six-membered cyclic sulfur diimides (3a—f) were prepared by aminolysis of the bis(chloro-dimethylsilyl)sulfur diimide (2) using NH3 (a) and primary amines RNH2 [R = Me (b), Et (c), nPr (d), nBu (e), iPr (f)]. Except for R = H, non-cyclic intermediates, the Si-monoamino- (7) and Si,Si′-diamino derivatives of 2 (8), were detetected for all groups R, including R = tBu (g). The reaction between R2SiCl2 and the sulfur diimide anion K[(NSN)SiMe3] gave non-cyclic silanes (9,10) and the eight-membered rings of the type R2Si(NSN)2SiR2 [R = Me (4), tBu (5)] of which 5 was studied by X-ray analysis (monoclinic, space group P21/c; planar ring system) and solid-state 15N and 29Si CP/MAS NMR spectroscopy. The ten-membered ring system 6 was obtained from the reaction between 1,2-dichlorotetramethyldisilane and bis(trimethylstannyl)sulfur diimide. All compounds were studied by 1H,13C, 15N and 29Si NMR. The δ15N NMR data proved useful to distinguish between fluxional systems with fast E/Z—Z/E isomerization (non-cyclic compounds 8 and the ten-membered cycle 6). Hahn-Echo-extended (HEED) polarization transfer (INEPT) pulse sequences served to measure coupling constants 1J(29Si15Namine) for the compounds 3 and 8. This also proved that the magnitude of 1J(29Si15NNSN) must be small (< 1 Hz). In the case of the compounds 3, the rather small magnitude of both 1J(29Si15Namine) and 1J(15N1H) (3a) indicated that the aminonitrogen atom adopts a pyramidal environment.