Synthesis and characterization of ferrocenylalkoxygermatranes and crystal structures of FcCH2OGe (OCH2CH2)3N and FcCH(CH3)OGe(OCH2CH2)3N1

Germatranes bearing a ferrocenylalkoxyl moiety have been obtained by the reaction of HOGe(OCH₂CH₂)₃N with various ferrocenyl alcohols. A convenient new synthesis method of FcCH₂OGe(OCH₂CH₂)₃N was reported. FcCH₂OGe(OCH₂CH₂)₃N was prepared in 93% yield when FcCH₂OH reacted with HOGe(OCH₂CH₂)₃N in chloroform at room temperature in the presence of molecular sieves (3 Å) as a dehydrating agent. All compounds were characterized by elemental analysis, ¹H NMR and IR spectroscopy. The molecular structures of FcCH₂OGe(OCH₂CH₂)₃N and FcCH(CH₃)OGe(OCH₂CH₂)₃N have been determined by X‐ray diffraction. The antitumor activities of FcCH₂OGe(OCH₂CH₂)₃N and p‐FcC₆H₄CH₂OGe(OCH₂CH₂)₃N were determined. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis of polyphosphazenes bearing alkoxyethoxy and trifluoroethoxy groups

The synthesis of various phosphoranimines including (CH₃OCH₂CH₂O) (CF₃CH₂O)₂P?N? Si(CH₃)₃, (CH₃OCH₂CH₂OCH₂CH₂O) (CF₃CH₂O)₂P?N? Si (CH₃)₃, (CH₃OCH₂CH₂O)₂(CF₃CH₂O) P?N? Si(CH₃)₃, and (CH₃OCH₂CH₂OCH₂CH₂O)(CF₃CH₂O) P?N? Si(CH₃)₃ via the Staudinger reaction of (CH₃)₃SiN₃ with the suitably substituted phosphite is reported. These monomers were polymerized using tetra-n-butylammonium fluoride and N-methylimidazole in various solvents at several temperatures. In situ ³¹P-NMR kinetic studies and M_n versus time studies were also performed for the monomers to understand the propagation mechanism. © 1994 John Wiley & Sons, Inc.     

Reactions of 1-(3"-Amino)- and 1-(3"-Acetamido)propylsilatranes with Cobalt(II) Chloride and Dicobalt Octacarbonyl

1-(3"-Amino)propylsilatrane (I) and 1-(3"-acetamido)propylsilatrane (II) react with anhydrous cobalt(II) chloride to give dichlorobis[1-(3"-amino)propylsilatrane]cobalt(II) {Co[NH₂CH₂CH₂CH₂Si(OCH₂CH₂)₃N]₂Cl₂} (III) and dichlorobis[1-(3"-acetamido)propylsilatrane]cobalt(II) {Co[CH₃C(O)NHCH₂CH₂CH₂Si(OCH₂CH₂)₃N]₂Cl₂} (IV). Being unstable, compound IV transforms into an imidic acid derivative. Reactions of silatranes I and II with dicobalt octacarbonyl afford hexakis[1-(3"-aminoamido)propylsilatrane]cobalt(II) bis(tetracarbonylcobaltate) {Co[NH₂CH₂CH₂CH₂Si(OCH₂CH₂)₃N]_4.8[HC(O)NHCH₂CH₂CH₂Si(OCH₂CH₂)₃N]_1.2}[Co(CO)₄]₂ (V) and hexakis[1-(3"-acetamido)propylsilatrane]cobalt(II) bis(tetracarbonylcobaltate) {Co[CH₃C(O)NHCH₂CH₂CH₂Si(OCH₂CH₂)₃N]₆}[Co(CO)₄]₂ (VI), respectively. In acetonitrile, tetracarbonylcobaltate anions of compound VI are oxidized with atmospheric oxygen and moisture to cobalt hydroxocarbonate, giving a carbonate gel (VII).     

Heteronuclear Alkoxide Compounds Containing Copper and Alkaline Earth Metals

The tetrameric Cu(β-diketonate) alkoxide complex [Cu(thd)(OCH₂CH₂OCH₃)]₄ (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate; 1a ) reacts with the alkaline earth metal alkoxides [M(OCH₂CH₂OCH₃)₂] (M = Ca, 2a ; M = Sr, 2b ; M = Ba, 2c ) to yield the heteronuclear compounds [Cu₂M(thd)₃(OCH₂CH₂OCH₃)₃] (M = Ca, 6a ; M = Sr, 6b ). These heterometallic complexes were also obtained in the reaction of 1a and the mixed Ca and Sr complexes of β-diketonate-alkoxide [M_x(thd)_y(OCH₂CH₂OCH₃)_2x?y] (M = Ca, x = 7, y = 6, 3 ; M = Sr, x = 5, y = 3, 4 ), respectively. In comparison, 1a reacts with the analogous [Ba(thd)(OCH₂CH₂OCH₃)] ( 5a ) to yield a[Ba₂Cu₂(thd)₄(OCH₃)₄(HOCH₂CH₂OCH₃)₂] species ( 8a .) The in situ prepared mixed-ligand Ba Compounds [Ba(thd)OR)] (R = CH₂CH₂OCH₂CH₂OCH₃, ( 5b ); R = CH₂CH₂CH₂OCH₃ ( 5c ) react with the corresponding Cu complexes [Cu(thd)(OR)]_n (R = CH₂CH₂OCH₂CH₂OCH₃), n = 4 ( 1b ); R = CH₂CH₂OCH₂CH₂OCH₃ ( 8b ); R = CH₂CH₂CH₂OCH₃ ( 8c ). However, [Cu(hfd)(OCH₂CH₂OCH₃)]₄ (hfd = 1,1,1,5,5,5,-hexafluoroacetylacetonate; 1e ) is converted in the presence of 2a–c to the simple metathesis products [M(hfd)₂] (M = Ca, Sr, Ba) and [Cu(OCH₂CH₂OCH₃)₂]. Crystalline [Ba₂Cu₂(hfd)₂(thd)₂(OCH₂CH₂CH₂OCH₃)₄(HOCH₂CH₂CH₂OCH₃)₂] ( 9 ) was isolated from the reaction of 1a with in situ prepared [Ba((hfd)OCH₂CH₂CH₂OCH₃)] ( 5d ) in 2-, methoxyethanol. X-Ray crystallographic structure determinations are reported for 6a , 6b , 8b , and 8c .     

Ligand‐Modification Effects on the Reactivity,Solubility, and Stability of Organometallic Tantalum Complexes in Water

Tantalum complexes [TaCp*Me{κ⁴‐C,N,O,O‐(OCH₂)(OCHC(CH₂NMe₂)?CH)py}] ( 4 ) and [TaCp*Me{κ⁴‐C,N,O,O‐(OCH₂)(OCHC(CH₂NH₂)?CH)py}] ( 5 ), which contain modified alkoxide pincer ligands, were synthesized from the reactions of [TaCp*Me{κ³‐N,O,O‐(OCH₂)(OCH)py}] (Cp*=η⁵‐C₅Me₅) with HC?CCH₂NMe₂ and HC?CCH₂NH₂, respectively. The reactions of [TaCp*Me{κ⁴‐C,N,O,O‐(OCH₂)(OCHC(Ph)?CH)py}] ( 2 ) and [TaCp*Me{κ⁴‐C,N,O,O‐(OCH₂)(OCHC(SiMe₃)?CH)py}] ( 3 ) with triflic acid (1:2 molar ratio) rendered the corresponding bis‐triflate derivatives [TaCp*(OTf)₂{κ³‐N,O,O‐(OCH₂)(OCHC(Ph)?CH₂)py}] ( 6 ) and [TaCp*(OTf)₂{κ³‐N,O,O‐(OCH₂)(OCHC(SiMe₃)?CH₂)py}] ( 7 ), respectively. Complex 4 reacted with triflic acid in a 1:2 molar ratio to selectively yield the water‐soluble cationic complex [TaCp*(OTf){κ⁴‐C,N,O,O‐(OCH₂)(OCHC(CH₂NHMe₂)?CH)py}]OTf ( 8 ). Compound 8 reacted with water to afford the hydrolyzed complex [TaCp*(OH)(H₂O){κ³‐N,O,O‐(OCH₂)(OCHC(CH₂NHMe₂)?CH₂)py}](OTf)₂ ( 9 ). Protonation of compound 8 with triflic acid gave the new tantalum compound [TaCp*(OTf){κ⁴‐C,N,O,O‐(OCH₂)(HOCHC(CH₂NHMe₂)?CH)py}](OTf)₂ ( 10 ), which afforded the corresponding protonolysis derivative [TaCp*(OTf)₂{κ³‐N,O,O‐(OCH₂)(HOCHC(CH₂NHMe₂)?CH₂)py}](OTf) ( 11 ) in solution. Complex 8 reacted with CNtBu and potassium 2‐isocyanoacetate to give the corresponding iminoacyl derivatives 12 and 13 , respectively. The molecular structures of complexes 5 , 7 , and 10 were established by single‐crystal X‐ray diffraction studies.     

Neue Metallatrane von Übergangselementen: Chloro- und Cyclopentadienyltitatran und Chloro- und Acetatozirconatran

New Metallatranes of Transition Elements: Chloro- and Cyclopentadienyltitatrane and Chloro- and Acetatozirconatrane Synthesis and characterization of chloro- and cyclopentadienyltitatrane, [ClTi(OCH₂CH₂)₃N]₂ and [CpTi(OCH₂CH₂)₃N], and of chloro- and acetatozirconatrane, [ClZr(OCH₂CH₂)₃N]_n and [CH₃CO₂Zr(OCH₂CH₂)₃N]₂, as well are described as new types of metallatranes of transition elements.     

Synthesis of new titanatranes containing organic substituents in the atrane fragment

Titanatrane CpTi(OCH(CH₃)CH₂)₃N (3) was prepared by the reaction of CpTiCl₃ with N(CH₂CH(CH₃)OH)₃ in the presence of triethylamine. The reaction of CpTi(OMe)₃ (8) with N(CH₂CH₂OH)₂(CH₂CHPhOH), erythro-N(CH₂CH₂OH)₂(CHPhCHPhOH), and N(CH₂CH₂OH)₂(CH₂CPh₂OH) gave cyclopentadienyltitanatranes 12–14. Compound 8 reacts with threo-N(CH₂CH₂OH)₂(CHPhCHPhOH) to give a mixture of threo-CpTi(OCH₂CH₂)₂(OCHPhCHPh)N and threo-MeOTi(OCH₂CH₂)₂(OCHPhCHPh)N. Slow hydrolysis of the latter product gave threo-[Ti₃O(OMe){(OCH₂CH₂)₂₋ (OCHPhCHPh)N} ₃]₂, which was studied by X-ray diffraction analysis. The crystal structures of 3 and 12 were also determined by X-ray diffraction analysis. The titanium coordination polyhedron in these complexes is a distorted trigonal bipyramid in which the equatorial positions are occupied by three oxygen atoms and the axial positions contain the N atom and the Cp group. The titanium—nitrogen distances (2.313(2), 2.291(2) Å in two independent molecules of 3 and 2.271(2) Å in compound 12) confirm the presence of Ti←N transannular interaction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2736–2744, December, 2005.     

1-Acyloxygermatranes

A one-step method for the synthesis of 1-acyloxygermatranes RC(O)OGe(OCH₂CH₂)₃N in the reaction of germanium dioxide with triethanolamine and a carboxylic acid was developed. 1-Acyloxygermatranes, including those containing biologically active acyloxy groups (R = 2-MeC₆H₄CH₂OCH₂, C₆H₅, 2-HOC₆H₄), were obtained with a 82–96.5% yield.     

Relation between the Length of the Transannular Bond Si←N in 1-Substituted Silatranes and the Inductive Effect of Substituents at the Silicon Atom

A strict linear correlation is found between the length of the coordination bond Si-N in 1-substituted silatranes XCH₂Si(OCH₂CH₂)₃N and the inductive constant _I of substituent XCH₂. This equation is also valid for other compounds of the RSi(OCH₂CH₂)₃N type, in which silicon is bound to an sp ²-carbon atom (R = CH = CH₂, Ph, 2-furyl, 2-thienyl, etc.). The deduced correlation equation allows determination of earlier unknown and refinement of existing _4I constants of substituents R on the basis of X-ray diffraction Si-N bond lengths in silatranes RSi(OCH₂CH₂)₃N. Deviations from the correlation point to noninductive interaction between substituent R and the silantranyl group (R = R'O). The bond length in 1-fluorosilatrane nicely fits the deduced equation.     

Gas-phase ion–molecule reactions in dilute mixtures of dimethyl ether in krypton. Bimolecular and clustering reactions

The results of high-pressure variable-temperature and variable ionizing electron energy studies of gas-phase ion-molecule reactions of dimethyl ether in krypton are presented. Near the ionization threshold a series of peaks corresponding to (CH₃OCH₃)_nH⁺ (n = 1-4) clusters are observed. At higher ionizing electron energies, two new series of peaks appear, corresponding to [CH₃OCH₂]⁺(CH₃OCH₃)_n and [(CH₃)₃O]⁺ (CH₃OCH₃)_n clusters. The onium ion, [(CH₃)₃O]⁺, has been previously reported at elevated temperatures under methane chemical ionization conditions. It was suggested that the onium ion is formed by reaction of (CH₃)₂OH⁺ with CH₃OCH₃ with subsequent elimination of methanel, i.e. by fragmentation of an adduct ion. The present results strongly suggest that, under our conditions, [CH₃OCH₂]⁺ rather than thermal (CH₃)₃OH⁺, is the precursor to [(CH₃)₃O]⁺.     

Hammett MSP and Taft DSP analysis of substituent effects on Mulliken charges of 1‐(arylmethylene)‐1H‐cyclopropanaphthalene

Density functional theory (DFT) method is used to investigate the effects of a variety of substituents (N(CH₃)_2, OCH_3, CH₃,Br, H, F, CN, and NO₂) on Mulliken charge (Q_M) for C‐α and C‐β of 1‐(Arylmethylene)‐1H‐cyclopropanaphthalene using Hammett's mono substituent parameter (MSP) and Taft's dual substituent parameter (DSP) models. The Hammett's model approach gave statistically more significant results than the Taft's model for both carbons atoms. For the C‐α atom a reverse substituent effect was observed and attributed to localized π‐polarization. On the other hand, the MSP and DSP for the C‐β atom showed normal substituent effect. The λ value at the C‐α, explain that the resonance effects more contribution than inductive effects. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Synthesis and1H NMR study of some organotin derivatives of diethanolamines

A number of organotin derivatives of diethanolamines (stannocanes) R₂Sn(OCH₂CH₂)₂NR', O(SiMe₂CH₂)₂Sn(OCH₂CH₂)₂NR', and Sn[(OCH₂CH₂)₂NR']₂ (R = Ph,cyclo-Hex; R' = H, Me, Ph) were synthesized and studied by¹H NMR spectroscopy. The effect of steric factors on the ability of molecules of stannocanes to form associates in solutions is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp.714–718, April, 1994.     

Fluordiazadiphosphetidine, 17. Mitt.

The reactions of (CH₃NPF₃)₂ and F₃P(CH₃N)₂PF₂OCH₃ with lithium-1,1,1-trimethyl-N-(trimethylsilyl)-silanamide yield two new dispiro-compounds:XF₂P(CH₃N)₂PF(NSiCH₃)₂PF(CH₃N)₂PF₂ X withX=F, OCH₃. Synthesis, mass-spectra and X-ray structures are discussed.

Herrn Prof. Dr.K. L. Komarek zum 60. Geburtstag gewidmet.     

A Quick Procedure for the Preparation of 1-N,N-Dialkylamino-1-Buten-3-Ynes

1-N,N-Dialkylamino-1-buten-3-ynes, HC°CCH[tbnd]CHNR₂ (R [dbnd] CH₃ or C₂H₅, E / Z ratio ～ 97: 3) have been prepared in 80 and 84% yields by treating the Mannich-coupling products from HC[dbnd]CCH₂OCH₃ and R₂NCH₂OH, CH₃OCH₂C[tbnd]CCH₂NR₂, with two equivalents of potassium amide in liquid ammonia and subsequently adding methanol or ammonium chloride.     

Molecular structure of 1-methyl-1-fluoroquasisilatrane (2-methyl-2-fluoro-1,3-dioxa-6-aza-2-silacyclooctane)

The molecular structure of 1-methyl-1-fluoroquasisilatrane (2-methyl-2-fluoro-1,3-dioxa-6-aza-2-silacyclooctane) MeFSi(OCH₂CH₂)₂NH (I) is determined by single crystal X-ray diffraction at 100 K. The coordination polyhedron of the silicon atom in this molecule is a slightly distorted trigonal bipyramid with an NH group and a strongly electron-withdrawing fluorine atom in the axial positions, and two endocyclic oxygen atoms and a CH₃ group in three vertices of the equatorial plane. The axial angle N→SiF is 171°. The length of the transannular donor-acceptor bond N→Si (2.058 Å) is as small as in 1-fluorosilatrane. The axial bond F-Si (1.660 Å) is longer than that in 1-fluorosilatrane and tetrahedral silicon compounds.     

Direct synthesis of 1-organylsilatranes from organyltrichlorosilanes and tris(2-hydroxyethyl)amine

A direct method of synthesis of 1-organylsilatranes by the reaction of organyltrichlorosilanes with tris(2-hydroxyethyl)amine was developed. 1-Organylsilatranes RSi(OCH₂CH₂)₃N with R = Me, Et, Ph, ClCH₂, ICH₂, Cl(CH₂)₃ were prepared by this method in up to 72% yield.     

Novel Copolymers of Styrene and Alkoxy Ring‐Substituted 2‐Cyano‐N,N‐Dimethyl‐3‐Phenyl‐2‐Propenamides

Electrophilic trisubstituted ethylene monomers, alkoxy ring‐substituted 2‐cyano‐N,N‐dimethyl‐3‐phenyl‐2‐propenamides, RC₆H₄CH?C(CN)CON(CH₃)₂ (where R is 2‐OCH₃, 3‐OCH₃, 4‐OCH₃, 2‐OCH₂CH₃, 3‐OCH₂CH₃, 4‐OCH₂CH₂CH₃, 4‐OCH₂CH₂CH₂CH₃), were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and N,N‐dimethyl cyanoacetamide, and characterized by CHN elemental analysis, IR, ¹H‐ and ¹³C‐NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ACBN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 300–450°C range.     

Synthese und Charakterisierung neuer intramolekular stickstoffstabilisierter Organoaluminium‐ und Organogalliumalkoxide

Synthesis and Characterization of New Intramolecularly Nitrogen‐stabilized Organoaluminium‐ and Organogallium Alkoxides The intramolecularly nitrogen stabilized organoaluminium alkoxides [Me₂Al{μ‐O(CH₂)₃NMe₂}]₂ ( 1a ), Me₂AlOC₆H₂(CH₂NMe₂)₃‐2,4,6 ( 2a ), [(S)‐Me₂Al{μ‐OCH₂CH(i‐Pr)NH‐i‐Pr}]₂ ( 3a ) and [(S)‐Me₂Al{μ‐OCH₂CH(i‐Pr)NHCH₂Ph}]₂ ( 4 ) are formed by reacting equimolar amounts of AlMe₃ and Me₂N(CH₂)₃OH, C₆H₂[(CH₂NMe₂)₃‐2,4,6]OH, (S)‐i‐PrNHCH(i‐Pr)CH₂OH, or (S)‐PhCH₂NHCH(i‐Pr)CH₂OH, respectively. An excess of AlMe₃ reacts with Me₂N(CH₂)₂OH, Me₂N(CH₂)₃OH, C₆H₂[(CH₂NMe₂)₃‐2,4,6]OH, and (S)‐i‐PrNHCH(i‐Pr)CH₂OH producing the “pick‐a‐back” complexes [Me₂AlO(CH₂)₂NMe₂](AlMe₃) ( 5 ), [Me₂AlO(CH₂)₃NMe₂](AlMe₃) ( 1b ), [Me₂AlOC₆H₂(CH₂NMe₂)₃‐2,4,6](AlMe₃)₂ ( 2b ), and [(S)‐Me₂AlOCH₂CH(i‐Pr)NH‐i‐Pr](AlMe₃) ( 3b ), respectively. The mixed alkyl‐ or alkenylchloroaluminium alkoxides [Me(Cl)Al{μ‐O(CH₂)₂NMe₂}]₂ ( 6 ) and [{CH₂=C(CH₃)}(Cl)Al{μ‐O(CH₂)₂NMe₂}]₂ ( 8 ) are to obtain from Me₂AlCl and Me₂N(CH₂)₂OH and from [Cl₂Al{μ‐O(CH₂)₂NMe₂}]₂ ( 7 ) and CH₂=C(CH₃)MgBr, respectively. The analogous dimethylgallium alkoxides [Me₂Ga{μ‐O(CH₂)₃NMe₂}]₂ ( 9 ), [(S)‐Me₂Ga{μ‐OCH₂CH(i‐Pr)NH‐i‐Pr}]_n ( 10 ), [(S)‐Me₂Ga{μ‐OCH₂CH(i‐Pr)NHCH₂Ph}]_n ( 11 ), [(S)‐Me₂Ga{μ‐OCH₂CH(i‐Pr)N(Me)CH₂Ph}]_n ( 12 ) and [(S)‐Me₂Ga{μ‐OCH₂(C₄H₇NHCH₂Ph)}]_n ( 13 ) result from the equimolar reactions of GaMe₃ with the corresponding alcohols. The new compounds were characterized by elemental analyses, ¹H‐, ¹³C‐ and ²⁷Al‐NMR spectroscopy, and mass spectrometry. Additionally, the structures of 1a , 1b , 2a , 2b , 3a , 5 , 6 and 8 were determined by single crystal X‐ray diffraction.     

Tin Tetrachloride Adducts with Arylphosphoramidates: A Multinuclear (31P, 19F,and 119Sn) NMR Characterization in Solution

Abstract

The synthesis of octahedral complexes [SnCl₄L₂] (L = R₂NP(O)(OCH₂CF₃)(O-p-tolyl): R₂N = Me₂N (1), Et₂N (2), CH₂(CH₂CH₂)₂N (3), and O(CH₂CH₂)₂N (4), or L = R₂NP(O)(OCH₂CF₃)(O-p-PhNO₂): R₂N = Me₂N (5), Et₂N (6), and O(CH₂CH₂)₂N (7) is described. The new adducts have been characterized by multinuclear (³¹P, ¹⁹F, ¹¹⁹Sn) NMR, IR spectroscopy, and elemental analyses. The solution NMR data show the presence of a mixture of cis and trans isomers. The structure of the complexes in solution was further confirmed by ¹¹⁹Sn NMR spectra, which display a triplet for each isomer, indicating an octahedrally coordinated tin center. The effects of the nature of R and Ar substituents on the donor ability of the P=O group in the ligands R₂NP(O)(OCH₂CF₃)(OAr) were investigated on the basis of ¹¹⁹Sn NMR chemical shifts and used to classify these ligands according to their Lewis basicity.     

Syntheses,spectroscopic study and crystal structures of some new <Emphasis Type="Italic">N</Emphasis>-benzoylphosphoric triamides

The reaction of N-benzoylphosphoramidic dichloride with amines afforded some new N-benzoylphos-phoric triamides with formula C₆H₅C(O)NHP(O)(X)₂, X=NH–CH(CH₃)₂ (1), NH–CH₂–CH(CH₃)₂ (2), NH–CH₂–CH(OCH₃)₂ (3), N(CH₃)[CH₂CH(OCH₃)₂] (4) and N(CH₃)(C₆H₁₁) (5) that were characterized by ¹H,¹³C,³¹P NMR, IR spectroscopy and elemental analysis. The structures have been determined for compounds 4 and 5 by X-ray crystallography. These compounds contain one amidic hydrogen atom and form centrosymmetric dimmers via intermolecular –P–O⋯H–N–hydrogen bonds besides weak C–H⋯O hydrogen bonds that lead to three-dimensional polymeric clusters in the crystalline lattice.