Structural investigations on new iron-acyl derivatives of B(C6F5)3

Reactions between [Fe(η-C₅H₅)(MeCO)(CO)(L)], L = PPh₃ (1), PMe₃ (2), PPhMe₂ (3), PCy₃ (4), CO (5), and B(C₆F₅)₃ give new complexes [Fe(η-C₅H₅){MeCOB(C₆F₅)₃}(CO)(L)] L = PPh₃ (7), PMe₃ (8), PPhMe₂ (9), PCy₃ (10), CO (11), where B(C₆F₅)₃ coordinates selectively to the O-acyl groups. Hydrolysis of 7 gives [Fe(η-C₅H₅){HOB(C₆F₅)₃}(CO)(PPh₃)] (6). The X-ray structures of 6, 8 and 11 have been determined. Calculations, using density functional theory, demonstrate that the charge transfer to the acyl group on Lewis acid coordination is more significant in the σ than the π system. Both effects lead to a lengthening of the acyl C-O bond thus π populations cannot be inferred from the distance changes.     

Syntheses, crystal structures and DFT studies of [Me3EM(CO)5] (E = Sb, Bi; M = Cr, W), cis-[(Me3Sb)2Mo(CO)4], and [Bu3BiFe(CO)4]

Syntheses of [Me₃SbM(CO)₅] [M = Cr (1), W (2)], [Me₃BiM(CO)₅] [M = Cr (3), W (4)], cis-[(Me₃Sb)₂Mo(CO)₄] (5), [^tBu₃BiFe(CO)₄] (6), crystal structures of 1-6 and DFT studies of 1-4 are reported.     

Synthesis and crystal structure of the double cluster [Cp3Fe4(CO)4(C5H4)]2(p-C6H4)

[Cp₄Fe₄(CO)₄] (1) reacts with p-BrC₆H₄Li and MeOH in sequence to afford the functionalized cluster [Cp₃Fe₄(CO)₄(C₅H₄-p-C₆H₄Br)] (2), while the reaction of 2 with n-BuLi and MeOH produces [Cp₂Fe₄(CO)₄(C₅H₄Bu)(C₅H₄-p-C₆H₄Br)] (3). The double cluster [Cp₃Fe₄(CO)₄(C₅H₄)]₂(p-C₆H₄) (4) has been prepared by treatment of [Cp₄Fe₄(CO)₄] with p-C₆H₄Li₂ and MeOH in sequence. The electrochemistry of 2 and 4, as well as the crystal structure of 4 have been investigated.     

Reactivity of [Re2(CO)8(MeCN)2] with thiazoles: Hydrido bridged dirhenium compounds bearing thiazoles in different coordination modes

Reactions of the labile compound [Re₂(CO)₈(MeCN)₂] with thiazole and 4-methylthiazole in refluxing benzene afforded the new compounds [Re₂(CO)₇{μ-2,3-η²-C₃H(R)NS}{η¹-NC₃H₂(4-R)S}(μ-H)] (1, R = H; 2, R = CH₃), [Re₂(CO)₆{μ-2,3-η²-C₃H(R)NS}{η¹-NC₃H₂(4-R)S}₂(μ-H)] (3, R = H; 4, R = CH₃) and fac-[Re(CO)₃(Cl){η¹-NC₃H₂(4-R)S}₂] (5, R = H; 6, R = CH₃). Compounds 1 and 2 contain two rhenium atoms, one bridging thiazolide ligand, coordinated through the C(2) and N atoms and a η¹-thiazole ligand coordinated through the nitrogen atom to the same Re as the thiazolide nitrogen. Compounds 3 and 4 contain a Re₂(CO)₆ group with one bridging thiazolide ligand coordinated through the C(2) and N atoms and two N-coordinated η¹-thiazole ligands, each coordinated to one Re atom. A hydride ligand, formed by oxidative-addition of C(2)-H bond of the ligand, bridges Re-Re bond opposite the thiazolide ligand in compounds 1-4. Compound 5 contains a single rhenium atom with three carbonyl ligands, two N-coordinated η¹-thiazole ligands and a terminal Cl ligand. Treatment of both 1 and 2 with 5 equiv. of thiazole and 4-methylthiazole in the presence of Me₃NO in refluxing benzene afforded 3 and 4, respectively. Further activation of the coordinated η¹-thiazole ligands in 1-4 is, however, unsuccessful and results only nonspecific decomposition. The single-crystal XRD structures of 1-5 are reported.     

Reactivity of 2,3-bis(2-pyridyl)pyrazine with [Re2(CO)8(CH3CN)2]: Molecular structures of [Re2(CO)8(C14H10N4)] and [Re2(CO)8(C14H10N4)Re2(CO)8]

The reaction of the labile compound [Re₂(CO)₈(CH₃CN)₂] with 2,3-bis(2-pyridyl)pyrazine in dichloromethane solution at reflux temperature afforded the structural dirhenium isomers [Re₂(CO)₈(C₁₄H₁₀N₄)] (1 and 2), and the complex [Re₂(CO)₈(C₁₄H₁₀N₄)Re₂(CO)₈] (3). In 1, the ligand is σ,σ′-N,N′-coordinated to a Re(CO)₃ fragment through pyridine and pyrazine to form a five-membered chelate ring. A seven-membered ring is obtained for isomer 2 by N-coordination of the 2-pyridyl groups while the pyrazine ring remains uncoordinated. For 2, isomers 2a and 2b are found in a dynamic equilibrium ratio [2a]/[2b]  =  7 in solution, detected by ¹H NMR (−50 °C, CD₃COCD₃), coalescence being observed above room temperature. The ligand in 3 behaves as an 8e-donor bridge bonding two Re(CO)₃ fragments through two (σ,σ′-N,N′) interactions. When the reaction was carried out in refluxing tetrahydrofuran, complex [Re₂(CO)₆(C₁₄H₁₀N₄)₂] (4) was obtained in addition to compounds 1-3. The dinuclear rhenium derivative 4 contains two units of the organic ligand σ,σ′-N,N′-coordinated in a chelate form to each rhenium core. The X-ray crystal structures for 1 and 3 are reported.     

Synthetic, X-ray structural and protonation studies of CpCr(CO)2SPy and CpCr(CO)2SPym (SPy = C5H4NS, SPym = C4H3N2S)

The facile reaction of [CpCr(CO)₃]₂ (Cp = η⁵-C₅H₅) (1) with one mole equivalent of 2,2′-dithiodipyridine ((C₅H₄NS)₂(SPy)₂) at ambient temperature led to the isolation of dark brown crystalline solids of CpCr(CO)₂(η²-SPy) (2) in ca. 72% yield. 2 undergoes quantitative conversion to CpCrCl₂(η¹-SPyH) (3) with HCl. The reaction 1 with one mole equivalent of 2-mercaptopyrimidine (C₄H₃N₂SHHSPym) at ambient temperature led to the isolation of reddish-brown crystalline solids of CpCr(CO)₂(η²-SPym) (4) and green solids of CpCr(CO)₃H (5) in yields of ca. 42% and 46%, respectively. Reaction of 4 with HCl and subsequent workup in acetonitrile resulted in the cleavage of the thiolate ligand, giving the 15-electron chromium(III) species CpCrCl₂(CH₃CN) (6) and free 2-mercaptopyrimidine. The complexes 2-4 have been determined by single X-ray diffraction analysis.     

Reactions of 1,8-bis(diphenylphosphino)naphthalene with Os3(CO)12: C-H and C-P bond cleavage reactions

Reactions of Os₃(CO)₁₂ with 1,8-bis(diphenylphosphino)naphthalene (dppn) are described. Crystallographically characterised complexes isolated from a reaction carried out in refluxing toluene are Os₃(μ-H)₂{μ-PPh₂(nap)PPh(C₆H₄)}₂(CO)₆ (1), Os₃(μ-H){μ₃-PPh₂(nap)PPh(C₆H₄)}(CO)₈ (2) and Os₂(μ-PPh₂){μ-PPh₂(nap)}(CO)₅ (3) (nap=1,8-C₁₀H₆), while at r.t. in the presence of ONMe₃, only Os₃(CO)₁₁{PPh₂(1-C₁₀H₇)} (4) was isolated. While 1 and 2 contain ligands formed by metallation of a Ph group of dppn, as found also in complexes obtained from dppn and Ru₃(CO)₁₂, ligands in 3 and 4 are formed by cleavage of a P-nap bond, not found in the Ru series.     

Synthesis, characterization, and substituent effects of mononuclear ruthenium complexes [RuCl(CO)(PMe3)3(CHCH-C6H4-R-p)] (R = H, CH3, OCH3, NO2, NH2, NMe2)

A series of mononuclear ruthenium complexes [RuCl(CO)(PMe₃)₃(CHCH-C₆H₄-R-p)] (R = H (2a), CH₃ (2b), OCH₃ (2c), NO₂ (2d), NH₂ (2e), NMe₂ (2f)) has been prepared. The respective products have been characterized by elemental analyses, NMR spectrometry, and UV-Vis spectrophotometry. The structures of complexes 2c and 2d have been established by X-ray crystallography. Electrochemical studies have revealed that electron-releasing substituents facilitate monometallic ruthenium complex oxidation, and the substituent parameter values (σ) show a strong linear correlation with the anodic half-wave or oxidation peak potentials of the complexes.     

Synthesis and diphosphine ligand fluxionality in Os3(CO)10(bmi): Kinetic evidence for nondissociative diphosphine isomerization and X-ray crystal structure of 1,1-Os3(CO)10(bmi)

The triosmium cluster 1,2-Os₃(CO)₁₀(MeCN)₂ reacts rapidly with the diphosphine ligand 2,3-bis(diphenylphosphino)-N-p-tolylmaleimide (bmi) at room temperature to give bmi-bridged cluster 1,2-Os₃(CO)₁₀(bmi) (2b) as the major product, along with the chelating isomer 1,1-Os₃(CO)₁₀(bmi) (2c) and the hydride-bridged cluster HOs₃(CO)₉[μ-(PPh₂)CC{PPh(C₆H₄)}C(O)N(tolyl-p)C(O)] (3) as minor by-products. All three cluster compounds have been isolated and fully characterized in solution by IR and NMR spectroscopies (¹H and ³¹P), and X-ray crystallography in the case of 2c. Cluster 2b is unstable and readily isomerizes to 2c in quantitative yield on mild heating. The kinetics for the conversion of 2b → 2c have been measured over the temperature range of 318-348 K in toluene solution, and based on the observed activation parameters a nondissociative isomerization process that proceeds via a transient μ₂-bridged phosphine moiety is presented. Near-UV photolysis of cluster 2c at room temperature affords HOs₃(CO)₉[μ-(PPh₂)CC{PPh(C₆H₄)}C(O)N(tolyl-p)C(O)] (3) with a quantum yield of 0.017. The reactivity of clusters 2b, 2c, and 3 is discussed with respect to related diphosphine-substituted Os₃(CO)₁₀(P-P) clusters prepared by our groups.     

Cp2Ti{[OC(O)C5H4]Cr(CO)2NO]}2 and Cp2Ti{[(OC(O)C5H4]Cr(NO)2X}2 syntheses and spectra of chromium-titanium complexes bridged by carboxylate substituted cyclopentadienyl group

Complete demethylation of Cp₂Ti(CH₃)₂ in dichloromethane with 2 M equivalent of [η⁵-(C₅H₄COOH)]Cr(CO)₂NO (5), [η⁵-(C₅H₄COOH)]Cr(NO)₂X] (X = Cl 6, X = I 7), and [η⁵-(C₅H₄COOH)]W(CO)₃CH₃ (8); gives Cp₂Ti{[OC(O)C₅H₄]Cr(CO)₂NO}₂ (13), Cp₂Ti{[OC(O)C₅H₄]Cr(NO)₂Cl}₂ (14), Cp₂Ti{[OC(O)C₅H₄]Cr(NO)₂I}₂ (15),and Cp₂Ti{[OC(O)C₅H₄]W(CO)₃CH₃}₂ (16), respectively. The chemical shifts of C(2)-C(5) carbon atoms of compounds 13-15 have been assigned using two-dimensional HetCOR NMR spectroscopy. The assigned chemical shifts were compared with the NMR data of their analogues of ferrocene, and the opposite correlation on the assignments was observed for cynichrodenoyl moieties.     

Reactivity of [CpCr(CO)3]2 towards thione (CS) moieties in some sulfur-containing substrates

The reaction of [CpCr(CO)₃]₂ (Cp = η⁵-C₅H₅) (1) with 1 mol equivalent of 2,5-dimercapto-1,3,4-thiadiazole (DMcTH₂) at ambient temperature led to the isolation of a reddish-brown crystalline solid of CpCr(CO)₃(η¹-DMcTH) (5) and a green solid of CpCr(CO)₃H (2) in yields of ca. 28% and 30%, respectively, along with some [CpCr(CO)₂]₂ (3) and [CpCr(CO)₂]₂S (4). The reaction of 1 with 1 mol equivalent of vinylene trithiocarbonate (SCS(CH)₂S) (VTTC) at 90 °C led to the isolation of a red crystalline solid of CpCr(CO)₂(η²-SCHSC₂H₂) (6) in ca. 15% yield while the reaction of 1 with isopropylxanthic disulfide ((CH₃)₂CHOCS₂)₂ resulted in the formation of CpCr(CO)₂(η²-S₂COCH(CH₃)₂) (8) in ca. 80% yield. The complexes 5, 6 and 8 have been determined by single crystal X-ray diffraction analysis.     

Reactions of Mo(II)-tetraphosphine complex [MoCl2{meso-o-C6H4(PPhCH2CH2PPh2)2}] with a series of small molecules

Reactions of Mo(II)-tetraphosphine complex [MoCl₂(κ⁴-P4)] (2; P4 = meso-o-C₆H₄(PPhCH₂CH₂PPh₂)₂) with a series of small molecules have been investigated. Thus, treatment of 2 with alkynes RCCR′ (R = Ph, R′ = H; R = p-tolyl, R′ = H; R = Me, R′ = Ph) in benzene or toluene gave neutral mono(alkyne) complexes [MoCl₂(RCCR′)(κ³-P4)] containing tridentate P4 ligand, which were converted to cationic complexes [MoCl(RCCR′)(κ⁴-P4)]Cl having tetradentate P4 ligand upon dissolution into CDCl₃ or CD₂Cl₂. The latter complexes were available directly from the reactions of 2 with the alkynes in CH₂Cl₂. On the other hand, treatment of 2 with 1 equiv. of XyNC (Xy = 2,6-Me₂C₆H₃) afforded a seven-coordinate mono(isocyanide) complex [MoCl₂(XyNC)(κ⁴-P4)] (7), which reacted further with XyNC to give a cationic bis(isocyanide) complex [MoCl(XyNC)₂(κ⁴-P4)]Cl (8). From the reaction of 2 with CO, a mono(carbonyl) complex [MoCl₂(CO)(κ⁴-P4)] (9) was obtained as a sole isolable product. Reaction of 9 with XyNC afforded [MoCl(CO)(XyNC)(κ⁴-P4)]Cl (10a) having a pentagonal-bipyramidal geometry with axial CO and XyNC ligands, whereas that of 7 with CO resulted in the formation of a mixture of 10a and its isomer 10b containing axial CO and Cl ligands. Structures of 7 and 9 as well as [MoCl(XyNC)₂(κ⁴-P4)][PF₆](8′) and [MoCl(CO)(XyNC)(κ⁴-P4)][PF₆] (10a′) derived by the anion metathesis from 8 and 10a, respectively, were determined in detail by the X-ray crystallography.     

Syntheses and spectra of chromium-titanium complexes bridged by carboxylate substituted cyclopentadienyl group: The structure of Cp2Ti(CH3){[OC(O)C5H4]Cr(NO)2Cl}

Mono-demethylation of Cp₂Ti(CH₃)₂ in dichloromethane with 1 M equivalent of [η⁵-(C₅H₄COOH)]Cr(CO)₂NO (5), [η⁵-(C₅H₄COOH)]Cr(NO)₂X] (X = Cl 6, X = I 7) and [η⁵-(C₅H₄COOH)]W(CO)₃CH₃ (8) gives Cp₂Ti(CH₃){[OC(O)C₅H₄]Cr(CO)₂NO} (9), Cp₂Ti(CH₃){[OC(O)C₅H₄]Cr(NO)₂Cl} (10), Cp₂Ti(CH₃){[OC(O)C₅H₄]Cr(NO)₂I} (11) and Cp₂Ti(CH₃){[OC(O)C₅H₄]W(CO)₃CH₃} (12), respectively. The structure of 10 has been solved by X-ray diffraction studies. One of the nitrosyl groups is located at the site away from the exocyclic carbonyl carbon of the Cp(Cr) ring with twist angle of 178.1°. All the data reveals that Cp₂Ti(CH₃)- is a strong electron-donating group. The opposite correlation was observed on the chemical shift assignments of C(2)-C(5) in compounds 5-12, using HetCOR NMR spectroscopy, as compared with the NMR data of their ferrocene analogues. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of ¹³C NMR data and those of 10 are compared with the calculations via density functional B3LYP correlation- exchange method.     

Preparation and characterization of rhenium (I) tricarbonyl dithiocarbamate compounds; Re(CO)3(S2CNMe2)(L)

The title compounds were prepared in good yield by treatment of Re(CO)₅Cl or [Re(CO)₃(H₂O)₃]Br with sodium dimethyldithiocarbamate hydrate (NaS₂CNMe₂·H₂O) and a neutral ligand yielding eight Re(CO)₃(S₂CNMe₂)(L) derivatives: L = NH₃1, pyridine (py) 2, imidazole (im) 3, pyrazole (pz) 4, triphenylphospine (PPh₃) 5, 1,3,5-triaza-7-phosphaadamantane (PTA) 6, t-butyl isocyanide (t-BuNC) 7, and cyclohexyl isocyanide (CyNC) 8. The resulting new complexes were characterized by ¹H and ¹³C NMR and infrared spectroscopy. Each was also structurally elucidated by X-ray crystallography. General structural features in all eight compounds were similar. The orientation of the three single-faced ligands, py, im and pz, demonstrates an interaction with the filled π orbital of the dithiocarbamate. Compounds were tested for stability under conditions that mimic physiological conditions; 1-4 quickly decomposed, 7 and 8 decomposed over 24 h while 5 and 6 were stable.     

Alkynyl Ti-M complexes based on M(CO)4 and MO2 building blocks (M = Mo, W)

The synthesis and properties of heterobimetallic Ti-M complexes of type {[[Ti](μ-η¹:η²-CCSiMe₃)][M(μ-η¹:η²-CCSiMe₃)(CO)₄]} (M = Mo: 5, [Ti] = (η⁵-C₅H₅)₂Ti; 6, [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti; M = W: 7, [Ti] = (η⁵-C₅H₅)₂Ti; 8, [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti) and {[Ti](μ-η¹:η²-CCSiMe₃)₂}MO₂ (M = Mo: 13, [Ti] = (η⁵-C₅H₅)₂Ti; 14, [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti). M = W: 15, [Ti] = (η⁵-C₅H₅)₂Ti; 16, [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti) are reported. Compounds 5-8 were accessible by treatment of [Ti](CCSiMe₃)₂ (1, [Ti] = (η⁵-C₅H₅)₂Ti; 2, [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti) with [M(CO)₅(thf)] (3, M = Mo; 4, M = W) or [M(CO)₄(nbd)] (9, M = Mo; 10, M = W; nbd = bicyclo[2.2.1]hepta-2,5-diene), while 13-16 could be obtained either by the subsequent reaction of 1 and 2 with [M(CO)₃(MeCN)₃] (11, M = Mo; 12, M = W) and oxygen, or directly by oxidation of 5-8 with air. A mechanism for the formation of 5-8 is postulated based on the in-situ generation of [Ti](CCSiMe₃)((η²-CCSiMe₃)M(CO)₅), {[Ti](μ-η¹:η²-CCSiMe₃)₂}-M(CO)₄, and [Ti](μ-η¹:η²-CCSiMe₃)((μ-CCSiMe₃)M(CO)₄) as a result of the chelating effect exerted by the bis(alkynyl) titanocene fragment and the steric constraints imposed by the M(CO)₄ entity.The molecular structure of 5 in the solid state were determined by single crystal X-ray diffraction analysis. In doubly alkynyl-bridged 5 the alkynides are bridging the metals Ti and Mo as a σ-donor to one metal and as a π-donor to the other with the [Ti](CCSiMe₃)₂Mo core being planar.     

Catalytic oxidation of diorganotin(IV) carboxylates to mixed-ligand monoalkyltin(IV) carboxylates by Ag and structure characterization of the mixed-ligand monoalkyltin(IV) 2-pyridinecarboxylate (2-ClPhCH2)Sn(2-ClPhCO2)(O2CC5H4N-2)2

The complexes of the type (ArCH₂)₂SnO were catalytic-oxygenated by Ag⁺ and yielded mixed-ligand organotin(IV) complexes (ArCH₂)(2-C₅H₄NCO₂)₂(ArCOO)tin(IV) (Ar = C₆H₅ (1), 2-ClC₆H₄ (2), 2-CNC₆H₄ (3), 4-ClC₆H₄ (4), 4-CNC₆H₄ (5), 2-FC₆H₄ (6)). The complexes 1-6 are characterized by elemental analyses, IR and NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopies. Single X-ray crystal structure analysis has been determined, which reveals that the center tin atom of complex 2 is seven-coordinated geometry.     

New cationic palladium (II) and rhodium (I) complexes of [Ph2PCH2C(Ph)N(2,6-Me2C6H3)]

Treatment of the bulky iminophosphine ligand [Ph₂PCH₂C(Ph)N(2,6-Me₂C₆H₃)] (L) with [M(CH₃CN)₂(ligand)]⁺ⁿ, where for M = Pd(II): ligand = η³-allyl, n = 1, and for M = Rh(I), ligand: 2(C₂H₄), 2(CO) or cod, n = 0, yields the mono-cationic iminophosphine complexes [Pd(η³-C₃H₅)(L)][BF₄] (1), [Rh(cod)(L)][BF₄] (2), [Rh(CO)(CH₃CN)(L)][BF₄] (3), and cis-[Rh(L)₂][BF₄] (4). All the new complexes have been characterised by NMR spectroscopy and X-ray diffraction. Complex 1 shows moderate activity in the copolymerisation of CO and ethene but is inactive towards Heck coupling of 4-bromoacetophenone and n-butyl acrylate.     

Hexapalladium cluster: Unique cluster construction reaction of cyclic Pd3(CNC6H3Me2-2,6)6 and linear [Pd3(CNC6H3Me2-2,6)8]

Reaction of a triangle Pd(0) complex, Pd₃(CNXyl)₆ (1; Xyl = 2,6-C₆H₃Me₂), with a dicationic linear trinuclear complex [Pd₃(CNXyl)₈][PF₆]₂ (3) afforded a dicationic hexapalladium complex [Pd₆(CNXyl)₁₂][PF₆]₂ (4), while the reaction of 1 with a dicationic dinuclear complex [Pd₂(CNXyl)₆][PF₆]₂ (2) resulted in the formation of 3. The molecular structure of the complex 4 was determined by X-ray crystallography and spectroscopic analysis.     

Synthesis and reactivity of para-substituted benzoylmethyltellurium(II and IV) compounds: observation of intermolecular C-H-O hydrogen bonding in the crystal structure of (p-MeOC6H4COCH2)2TeBr2

Bis(p-substituted benzoylmethyl)tellurium dibromides, (p-YC₆H₄COCH₂)₂TeBr₂, (Y=H (1a), Me (1b), MeO (1c)) can be prepared either by direct insertion of elemental Te across C_Rf-Br bonds (where C_Rf refers to α-carbon of a functionalized organic moiety) or by the oxidative addition of bromine to (p-YC₆H₄COCH₂)₂Te (Y=H (2a), Me (2b), MeO (2c)). Bis(p-substituted benzoylmethyl)tellurium dichlorides, (p-YC₆H₄COCH₂)₂TeCl₂ (Y=H (3a), Me (3b), MeO (3c)), are prepared by the reaction of the bis(p-substituted benzoylmethyl)tellurides 2a-c with SO₂Cl₂, whereas the corresponding diiodides (p-YC₆H₄COCH₂)₂TeI₂ (Y=H (4a), Me (4b), MeO (4c)) can be obtained by the metathetical reaction of 1a-c with KI, or alternatively, by the oxidative addition of iodine to 2a-c. The reaction of 2a-c with allyl bromide affords the diorganotellurium dibromides 1a-c, rather than the expected triorganotelluronium bromides. Compounds 1-4 were characterized by elemental analyses, IR spectroscopy, ¹H, ¹³C and ¹²⁵Te NMR spectroscopy (solution and solid-state) and in case of 1c also by X-ray crystallography. (p-MeOC₆H₄COCH₂)₂TeBr₂ (1c) provides, a rare example, among organotellurium compounds, of a supramolecular architecture, where C-H-O hydrogen bonds appear to be the non-covalent intermolecular associative force that dominates the crystal packing.