Reactions of 4-substituted 5H-1,2,3-dithiazoles with primary and secondary amines: fast and convenient synthesis of 1,2,5-thiadiazoles, 2-iminothioacetamides and 2-oxoacetamides

The treatment of 5H-1,2,3-dithiazole-5-thiones 1 in chloroform under reflux and 5H-1,2,3-dithiazol-5-ones 2 in THF at room temperature with primary aliphatic amines and benzylamine afforded 1,2,5-thiadiazole-3(2H)-thiones 3 and 1,2,5-thiadiazol-3(2H)-ones 6, respectively. The structure of dithiazolone 3f was confirmed by X-ray diffraction analysis. The reaction of dithiazolone 2e bearing an electron-donating methyl group in the 4-position gave 2-oxoacetamide 7e in high yield. The reaction of thiones 1 with secondary aliphatic amines in DMSO yielded 2-iminothioacetamides 8 in moderate yields together with elemental sulfur. Interestingly, the treatment of dithiazolones 2 with secondary amines under the same conditions afforded 2-oxoacetamides 9—the products of the hydrolysis of corresponding imino derivatives 10, which was isolated as 10b. A general mechanism was proposed for the formation of the products.     

Chemoselective ring opening of benzoxazaphosphinines

Cyclization of 2-[(4-chloroanilino)methyl]phenol (1) with thiophosphoryl chloride afforded 2-chloro-3-(4-chlorophenyl)-3,4-dihydro-2H-1,3,2λ⁵-benzoxazaphosphinine-2-thione (2). Reaction of 2 with various heterocyclic amines (3) in the presence of Et₃N/NaH gave 3-(4-chlorophenyl)-2-nitrogen heterocyclic substituted-3,4-dihydro-2H-1,3,2λ⁵-benzoxaza-phosphinine-2-thiones (4). Further reaction of 4 with the N-sodium salt of amino heterocyclics in the presence of HCl at 50-60 °C opened the benzoxazaphosphinine ring chemoselectively at the endocyclic P-O bond and yielded 2-[4-chloro(heterocyclic substituted-phosphorothioyl)anilino]methylphenols 5-13.     

An efficient microwave assisted synthesis of novel class of Rhodanine derivatives as potential HIV-1 and JSP-1 inhibitors

(Z)-5-(2-(1H-Indol-3-yl)-2-oxoethylidene)-3-phenyl-2-thioxothiazolidin-4-one (7a-q) derivatives have been synthesized by the condensation reaction of 3-phenyl-2-thioxothiazolidin-4-ones (3a-h) with suitably substituted 2-(1H-indol-3-yl)-2-oxoacetaldehyde (6a-d) under microwave condition. The thioxothiazolidine-4-ones were prepared from the corresponding aromatic amines (1a-e) and di-(carboxymethyl)-trithiocarbonyl (2). The aldehydes (6a-h) were synthesized from the corresponding acid chlorides (5a-d) using HSnBu₃.     

New iminophosphorane-mediated synthesis of thieno[3′,2′:4,5]thieno[3,2-d]pyrimidin-4(3H)-ones and 5H-2,3-dithia-5,7-diaza-cyclopenta[c,d]indenes

Mono(iminophosphorane) 4 was selectively prepared from the reaction of 3,4-diaminothieno[2,3-b]thiophene 3 with excess triphenylphosphine, C₂Cl₆, and Et₃N due to intramolecular double hydrogen bond formation. Mono(iminophosphorane) 4 reacted with aromatic isocyanates to give stable carbodiimides 8, which were further treated with aliphatic secondary or primary amines to give 2-amino substituted thieno[3′,2′:4,5]thieno[3,2-d]pyrimidin-4(3H)-ones 10 or 12 in the presence of a catalytic amounts of EtO⁻Na⁺. However, in the presence of a catalytic amounts of potassium carbonate, the carbodiimides 8 were transformed into previously unreported 5H-2,3-dithia-5,7-diaza-cyclopenta[c,d]indenes 13 via direct cyclization in high yields. The reaction of carbodiimides 8 with phenols in the presence of a catalytic amounts of potassium carbonate gave a mixture of 2-aryloxy substituted thieno[3′,2′:4,5]thieno[3,2-d]pyrimidin-4(3H)-ones 14 and 13. X-ray structure analysis of 10m supported the structure and the proposed reactivity of amino group.     

Hydro- and chloro-substituted silyl- and silyl-η-amido-η-tetramethylcyclopentadienyl titanium complexes

Chlorosilyl-cyclopentadienyl titanium precursors [Ti(η⁵-C₅Me₄SiMeXCl)Cl₃] (X=H 2, Cl 3) were prepared by reaction of TiCl₄ with the trimethylsilyl derivatives of the corresponding cyclopentadienes. Methylation of these compounds with MgClMe under appropriate conditions afforded the methyl complexes [Ti(η⁵-C₅Me₄SiMe₂R)XMe₂] (R=H, X=Cl 5, Me 6; R=X=Me 7). Reactions of 2 and 3 with two equivalents of LiNH^tBu afforded the ansa-silyl-η-amido compounds [Ti{η⁵-C₅Me₄SiMeX(η¹-N^tBu)}Cl₂] (X=H 8, Cl 9). Methylation of 8 gave [Ti{η⁵-C₅Me₄SiMeH(η¹-N^tBu)}Me₂] 10. Complex 9 was also obtained by reaction of 8 with BCl₃, whereas the same reaction using alternative chlorinating agents (TiCl₄, HCl) resulted in deamidation to give 2, which was also converted into 3 by reaction with BCl₃. All of the new compounds were characterized by NMR spectroscopy and the molecular structures of 2 and 4 were determined by X-ray diffraction methods.     

A practical one-pot procedure for the synthesis of pyrazino[2′,3′:4,5]thieno[3,2-d]pyrimidinones by a tandem aza-Wittig/heterocumulene-mediated annulation strategy

A simple one-pot and efficient method is described for the synthesis of pyrazino[2′,3′:4,5]thieno[3,2-d]pyrimidinone derivatives 6 via a tandem aza-Wittig/heterocumulene-mediated annulation process. The iminophosphorane 3 reacted with aryl isocyanates, followed by heterocyclization on addition of secondary amines to give the corresponding guanidine intermediates 5, which were cyclized in the presence of a catalytic amount of potassium carbonate to tricyclic compounds 6. Similarly, iminophosphorane 3 reacts with phenols, thiophenol, or ROH to give 2-aryl(alkyl)oxy(thio)pyrazino[2′,3′:4,5]thieno[3,2-d]pyrimidinone derivatives 7 in good yields. The corresponding carbodiimide 4c and guanidine-type intermediate compounds 5 could be isolated and characterized, thus confirming the suggested reaction pathway. However, two isomeric pyrazinothienopyrimidinones 8 and 9 may be produced in the reaction of iminophosphorane 3 with aromatic isocyanates and subsequent reaction with primary amines in the presence of a catalytic amount of potassium carbonate. The effects of the nucleophiles and isocyanates on the regioselectivity of the cyclization have been investigated.     

Ring transformation of chromone-3-carboxamide

4-Hydroxycoumarin-3-carboxaldehyde (5) was obtained from chromone-3-carboxaldehyde (1) via chromone-3-carboxamide (2) and 3-aminomethylene-2H-chroman-2,4-dione (3). 3-Alkylaminomethylenechroman-2,4-diones (7,8) were obtained from the reaction of primary aliphatic amines with chromone-3-carboxamide (2). Treatment of chromone-3-carboxamide with sodium methoxide gives 3-(2-hydroxybenzoyl)-2H-chromeno[2,3-b]pyridine-2,5(1H)-dione (9).     

Microwave-assisted synthesis of novel bis(2-thioxothiazolidin-4-one) derivatives as potential GSK-3 inhibitors

(5Z,5′Z)-3,3′-(1,4-Phenylenebis(methylene)-bis-(5-arylidene-2-thioxothiazolidin-4-one) derivatives (5a-r) have been synthesized by the condensation reaction of 3,3′-(1,4- or 1,3-phenylenebis(methylene))bis(2-thioxothiazolidin-4-ones) (3a,b) with suitably substituted aldehydes (4a-f) or 2-(1H-indol-3-yl)2-oxoacetaldehydes (8a-c) under microwave conditions. The bis(2-thioxothiazolidin-4-ones) were prepared from the corresponding primary alkyl amines (1a,b) and di-(carboxymethyl)-trithiocarbonyl (2). The 2-(1H-indol-3-yl)-2-oxoacetaldehydes (8a-c) were synthesized from the corresponding acid chlorides (7a-c) using HSnBu₃.     

New 1,2-disubstituted ferrocenyl stibines containing N-heterocyclic pendant arm: Sb-N hypervalent compounds

New 1,2-disubstituted ferrocenyl stibines viz. containing -CH₂NR or -CH₂NHR pendant arm at the ortho-position have been synthesized and characterized by various physicochemical methods. These new ferrocenylstibines were prepared by the nucleophilic substitution reaction of diphenyl[(N,N,N-trimethylaminomethylferrocenyl)iodide]stibine by different primary amines and secondary heterocyclic amines viz. furan-2-ylmethylamine, p-aminoacetophenone, 3-(1-hydroxyethyl)-aniline, 4-hydroxypiperidine, 1-ethylpiperazine and 4-(4-bromophenyl)-4-hydroxypiperidine. Molecular structure of stibine (2), (3), (5) and (7) have been determined by X-ray crystallography. Stibine (2), (5) and (7) show a weak hypervalent Sb-N interaction while stibine (3) does not show this interaction in solid state.     

Reactions of chelated η-pentadienyl iron complexes with nucleophiles

Ferracyclic (1-3-η³)pentadienyl complexes with electronically decoupled allyl and vinyl moieties were reacted with various heteroatom and carbon nucleophiles. Primary amines selectively attacked neutral (4-6-η³-pentadienyl)ferralactones 2 on the end of the allyl ligand to give 3-(endo-vinyl)-(4-6-η³-allyl)ferralactams 4 and by a similar reaction of the latter eventually 6-(exo-vinyl)-(4-6-η³-allyl)ferralactams 5. -like attack on the conjugated coplanar vinyl residue of 2 was not observed. The cationic η³-allyl complex 3 was attacked by nucleophiles either on the allylic terminus furnishing free (1Z, 3E)-dienes 8, or on the vinyl residue which is part of an activated Michael system to give η⁴-1,3-diene complexes 9. η⁴-1,3,5-Triene complex 10 was obtained with basic nucleophiles.     

Some novel observations on the reaction of 2-hydrazino-3-methylquinoxaline with trifluoromethyl-β-diketones

The reaction of 2-hydrazino-3-methylquinoxaline 1 with trifluoromethyl-β-diketones 2 not only yields the expected 5-trifluoromethyl-5-hydroxy-Δ²-pyrazolines 3a-3f and/or 3-trifluoromethylpyrazoles 4c-4f but also the unexpected products 1,2,4-triazolo[4,3-a]quinoxalines 5a-5f and/or 3(5)-trifluoromethyl-1H-pyrazoles 6c-6f. Furthermore, the acid-catalyzed dehydration of 5-hydroxypyrazolines 3a-3b resulted in the formation of unexpected 5a-5b along with the expected corresponding pyrazoles 7a-7b. These unprecedented observations provide evidence for the existence of equilibrium between the hydroxypyrazoline 3 and its open chain tautomer, ketoimine 9 in the mechanistic path leading to the formation of pyrazoles 7 and triazoles 5.     

Synthesis, IR-, NMR- and X-ray investigations on some novel N-hetaryl-dihydro-pyrazolyl ferrocenes. Study on ferrocenes, part 16

Cyclocondensation of 1-aryl-3-ferrocenyl-2-propen-1-ones (1) with hetaryl hydrazines resulted in N-hetaryl-3-aryl-5-ferrocenyl pyrazolines (3, 4). The analogous 3-aryl-1-ferrocenyl-2-propen-1-ones (5) gave the isomeric N-hetaryl-5-aryl-3-ferrocenyl-pyrazolines (6, 10), but in lower yield. The reaction of aryl-chalcones (7) with 4-hydrazino-phthalazinone led to 3,5-bis-aryl-N-hetaryl-pyrazolines (8) or to the corresponding ene-hydrazones (9). The structure of the new compounds was established by IR, ¹H and ¹³C NMR spectroscopy, including DNOE, HMQC, HMBC and DEPT methods. For compounds 1b, 3b and 8b the stereo structure was elucidated also by X-ray diffraction.     

Pyrrolide-imine benzyl complexes of zirconium and hafnium: synthesis, structures, and efficient ethylene polymerization catalysis

A series of pyrrolyl-imines HL^1-6 was prepared by the condensation of pyrrole-2-carboxyaldehyde with different amines. The reaction of 2 equiv of pyrrolyl-imine with tetrabenzyl complexes of hafnium and zirconium M(CH₂Ph)₄ (M=Hf or Zr) gave dibenzyl complexes (L^3-6)₂M(CH₂Ph)₂, which were characterized by NMR spectroscopy and crystal structure analysis. NMR spectra of the complexes with secondary alkyl substituents at the imine nitrogen (isopropyl: 3a, 4-tert-butylcyclohexyl: 4a and 4b) suggest that rapid racemization between Δ and Λ configurations occurs in solution on the NMR time scale. The complexes with pyrrolide-imine ligands with a tertiary alkyl group such as tert-butyl (5a and 5b) or 1-adamantyl (6a and 6b) at the imine nitrogen possess cis-configured benzyl groups. Hafnium complexes 5a and 6a react with B(C₆F₅)₃ in bromobenzene-d₅ to give the corresponding cationic benzyl complexes, which exhibit high activity for ethylene polymerization (5a: 2242 kg-polymer/ mol-Hf h bar, 6a: 2096 kg-polymer/ mol-Hf h bar). Zirconium complexes 5b and 6b display a remarkably high ethylene polymerization activity when activated with methylaluminoxane (5b: 17,952 kg-polymer/mol-Zr h bar, 6b: 22,944 kg-polymer/mol-Zr h bar).     

New silatranes possessing urea functionality: Synthesis, characterization and their structural aspects

The present work aims at the synthesis of various novel silatranes bearing substituted urea functionality. Nucleophilic addition of various amines (morpholine, aniline, ethylenediamine and 3-aminopropyltriethoxysilane) to 3-isocyanatopropyltriethoxysilane resulted in the four triethoxysilanes; N-[3-(triethoxysilyl)propyl]morpholine-4-carboxylic acid amide (1), 1-[3-(triethoxysilyl)propyl]-3-phenylurea (2), 1,2-bis{N′-[3-(triethoxysilyl)propyl]ureido}-ethane (3) and N-[3-(triethoxysilyl)propyl]-N′-[3-(triethoxysilyl)propyl]urea (4), respectively. In the presence of a base the resulting silanes undergo transesterification reaction with triethanolamine, thus forming the corresponding silatranes, N-(3-silatranylpropyl)morpholine-4-carboxylic acid amide (5), 1-(3-silatranylpropyl)-3-phenylurea (6), 1,2-Bis[N′-(3-silatranylpropyl)ureido]-ethane (7) and N-(3-silatranylpropyl)-N′-(3-silatranylpropyl)urea (8), respectively. Among these are four novel compounds (5-8), which were characterized by elemental analysis, IR, multinuclear (¹H, ¹³C and ²⁹Si) NMR and mass spectroscopy. Structures of compounds 5 and 6 were deduced by X-ray crystallography. Single crystal X-ray studies revealed distorted trigonal bipyramidal coordination about Si in 5 and 6 with Si-N bond distance of 2.121(1) Å and 2.189(2) Å, respectively.     

Synthesis and properties of 4,9-methanoundecafulvenes and their transformation to 3-substituted 7,12-methanocycloundeca[4,5]furo[2,3-d]pyrimidine-2,4(1H,3H)-diones: photo-induced autorecycling oxidizing reaction toward amines

The synthesis and properties of 4,9-methanoundecafulvene [5-(4,9-methanocycloundeca-2′,4′,6′,8′,10′-pentaenylidene)pyrimidine-2,4,6(1,3,5H)-trione] derivatives 8a,b were studied. Their structural characteristics were investigated on the basis of the ¹H and ¹³C NMR and UV-vis spectra. The rotational barrier (ΔG^‡) around the exocyclic double bond of 8a was found to be 12.55 kcal mol⁻¹ by the variable temperature ¹H NMR measurement. The electrochemical properties of 8a,b were also studied by CV measurement. Furthermore, the transformation of 8a,b to 3-substituted 7,12-methanocycloundeca[4,5]furo[2,3-d]pyrimidine-2,4(1H,3H)-diones 16a,b was accomplished by oxidative cyclization using DDQ and subsequent ring-opening and ring-closure. The structural details and chemical properties of 16a,b were clarified. Reaction of 16a with deuteride afforded C13-adduct 19 as the single product, and thus, the methano-bridge controls the nucleophilic attack to prefer endo-selectivity. The photo-induced oxidation reaction of 16a and a vinylogous compound, 3-methylcyclohepta[4,5]furo[2,3-d]pyrimidine-2,4(3H)-dione 2a, toward some amines under aerobic conditions were carried out to give the corresponding imines (isolated by converting to the corresponding 2,4-dinitrophenylhydrazones) with the recycling number of 6.1-64.0 (for 16a) and 2.7-17.2 (for 2a), respectively.     

Ring transformation of cyclohepta[b]pyrimido[5,4-d]furan-8(7H),10(9H)-dionylium ion to the corresponding pyrrole derivatives via troponeimine intermediates: photo-induced autorecycling oxidizing reactions of some amines

Ring transformation of 7,9-dimethylcyclohepta[b]pyrimido[5,4-d]furan- 8(7H),10(9H)-dionylium tetrafluoroborate 4⁺·BF₄⁻ to 7,9-dimethylcyclohepta[b]pyrimido[5,4-d]pyrrrole-8(7H),10(9H)-dionylium tetrafluoroborate 6a-d⁺·BF₄⁻ consists of the reaction of 4⁺·BF₄⁻ with amines and subsequent exchange of the counter-ion using aq. HBF₄. Reactions of 4⁺·BF₄⁻ with aniline and 4-substituted anilines afforded the corresponding pyrrole derivatives 6a-c⁺·BF₄⁻ directly in good yields. On the other hand, reaction of 4⁺·BF₄⁻ with benzylamine gave the troponeimine intermediate 9, which was not converted to 6d⁺·BF₄⁻ and reverted to 4⁺·BF₄⁻ by adding HBF₄; however, it was converted to 6d⁺·BF₄⁻ upon treatment with (COCl)₂ or SOCl₂, followed by exchange of the counter-ion. In a search for the characteristics of 9, inspection and comparison of the X-ray crystal analyses, NMR and UV-vis spectra, and CV measurement of 9 and N,N-disubstituted troponeimine derivatives 12 were carried out to suggest the remarkable structure of 12 having ionic C-O bonding between the imine-carbon atom and the oxygen atom of the barbituric acid moiety in the solid state. Thus, characteristics of 9 were ascribed to the sterically hindered and favorable conformation of N-protonated troponeimine intermediates. Furthermore, novel photo-induced oxidation reactions of a series of 4⁺·BF₄⁻, 5⁺·BF₄⁻, and 6a,e⁺·BF₄⁻ towards some amines under aerobic conditions were carried out to give the corresponding imines in 455-8362% yields [based on compounds 4⁺, 5⁺, and 6a,e⁺], suggesting the oxidation reaction occurs in an autorecycling process. Mechanistic aspects of the amine-oxidation reaction are also postulated.     

Aluminum and zinc complexes supported by functionalized phenolate ligands: Synthesis, characterization and catalysis in the ring-opening polymerization of ε-caprolactone and rac-lactide

A series of aluminum and zinc complexes supported by functionalized phenolate ligands were synthesized and characterized. Reaction of 2-(3,5-R₂C₃N₂)C₆H₄NH₂ (R = Me, Ph) with salicylaldehyde or 3,5-di-tert-butylsalicylaldehyde afforded 2-((2-(1H-pyrazol-1-yl)phenylimino)methyl)phenol derivatives 2a-2d. Treatment of 2a-2d with an equiv. of AlR²₃ (R² = Me, Et) gave corresponding aluminum aryloxides 3a-3e, while reaction with an equiv. of ZnEt₂ afforded zinc aryloxides 4a-4d. Treatment of 2c with 0.5 equiv. of ZnEt₂ formed diphenolato zinc complex 5. All new compounds were characterized by ¹H and ¹³C NMR spectroscopy and elemental analyses. The structures of complexes 3a, 4a and 5 were further characterized by single crystal X-ray diffraction techniques. The catalytic activity of complexes 3-5 toward the ring-opening polymerization of ε-caprolactone was studied. The zinc complexes (4a-4d) exhibited higher catalytic activity than the aluminum complexes (3a-3e). The diphenolato zinc complex 5 showed lower catalytic activity than the ethylzinc complexes 4a-4d. The aluminum complex (3b) is inactive to initiate the ROP of rac-lactide, while the zinc complex (4d) is active initiator for the ROP of rac-lactide, giving atactic polylactide.     

The intramolecular aromatic nucleophilic substitution as a route to tricyclic β-lactams. Synthesis of the novel 4-oxa-7-azabicyclo[4.2.0]octane skeleton

Sodium borohydride-carbonyl reduction of the novel 3-(2-fluoro-5-nitro) phenyl-4-benzoyl-2-azetidinones 3 and 7 gave quantitatively the stereoisomeric carbinols (4R^∗,5S^∗)-4 and (4R^∗,5R^∗)-5. Treatment of the latter with sodium hydride gave the title compounds 8 and 9, respectively, with good overall yield. The rationale of the stereochemical relationships outlined in the sequences 3 (or 7)→4→8 and 3 (or 7)→5→9 is given according to the conformational and keto-enol equilibria of the reactant(s).     

Synthesis and characterization of half-sandwich Rh, Ir complexes containing mono-thiolate-ortho-carborane ligand

Two binuclear complexes [Cp^∗M(Cl)Carb^S]₂ (Cp^∗ = η⁵-C₅Me₅, M = Rh (1a), Carb^S = SC₂(H)B₁₀H₁₀, Ir (1b)) were synthesized by the reaction of LiCarb^S with the dimeric metal complexes [Cp^∗MCl(μ-Cl)]₂ (M = Rh, Ir). Four mononuclear complexes Cp^∗M(Cl)(L)Carb^S (L = BuⁿPPh₂, M = Rh (2a), Ir (2b); L = PPh₃, M = Rh (4a), Ir (4b)) were synthesized by reactions of 1a or 1b with L (L = BuⁿPPh₂ (2); PPh₃ (4)) in moderate yields, respectively. Complexes 3a, 3b, 5a, 5b were obtained by treatment of 2a, 2b, 4a, 4b with AgPF₆ in high yields, respectively. All of these compounds were fully characterized by IR, NMR, and elemental analysis, and the crystal structures of 1a, 1b, 2a, 2b, 4a, 4b were also confirmed by X-ray crystallography. Their structures showed 3a, 3b and 5a, 5b could be expected as good candidates for heterolytic dihydrogen activation. Preliminary experiments on the dihydrogen activation driven by these half-sandwich Rh, Ir complexes were done under mild conditions.     

Syntheses and structures of iron carbonyl complexes derived from N-(5-methyl-2-thienylmethylidene)-2-thiolethylamine and N-(6-methyl-2-pyridylmethylidene)-2-thiolethylamine

The reaction of N-(5-methyl-2-thienylmethylidene)-2-thiolethylamine (1) with Fe₂(CO)₉ in refluxing acetonitrile yielded di-(μ₃-thia)nonacarbonyltriiron (2), μ-[N-(5-methyl-2-thienylmethyl)-η¹:η¹(N);η¹:η¹(S)-2-thiolatoethylamido]hexacarbonyldiiron (3), and N-(5-methyl-2-thienylmethylidene)amine (4). If the reaction was carried out at 45 °C, di-μ-[N-(5-methyl-2-thienylmethylidene)-η¹(N);η¹(S)-2-thiolethylamino]-μ-carbonyl-tetracarbonyldiiron (5) and trace amount of 4 were obtained. Stirring 5 in refluxing acetonitrile led to the thermal decomposition of 5, and ligand 1 was recovered quantitatively. However, in the presence of excess amount of Fe₂(CO)₉ in refluxing acetonitrile, complex 5 was converted into 2-4. On the other hand, the reaction of N-(6-methyl-2-pyridylmethylidene)-2-thiolethylamine (6) with Fe₂(CO)₉ in refluxing acetonitrile produced 2, μ-[N-(6-methyl-2-pyridylmethyl)-η¹ (N_py);η¹:η¹(N); η¹:η¹(S)-2-thiolatoethylamido]pentacarbonyldiiron (7), and μ-[N-(6-methyl-2-pyridylmethylidene)-η²(C,N);η¹:η¹(S)-2- thiolethylamino]hexacarbonyldiiron (8). Reactions of both complex 7 and 8 with NOBF₄ gave μ-[(6-methyl-2-pyridylmethyl)-η¹(N_py);η¹:η¹(N);η¹:η¹(S)-2-thiolatoethylamido](acetonitrile)tricarbonylnitrosyldiiron (9). These reaction products were well characterized spectrally. The molecular structures of complexes 3, 7-9 have been determined by means of X-ray diffraction. Intramolecular 1,5-hydrogen shift from the thiol to the methine carbon was observed in complexes 3, 7, and 9.