Bildung siliciumorganischer Verbindungen. XXXXI. Synthese und Reaktionen des 1,1,3,3,5,5-Hexamethyl-1,3,5-trisila-6-methylen-cyclohexan und des 1,1,3,3,5,5-Hexamethyl-1,3,5-trisila-cyclohepten-6

The compounds (a) and (b) have been synthesized, and their reactions with Br₂, HBr, HSiCl₃ and HSime₂Br (me = CH₃) are described. The synthesis of (a) and (b) can be achieved by cycloaddition of Hme2Si? CH₂? Sime₂? CH₂? Sime₂? C?CH (c). (a) is also formed by cyclisation of (d) and (e) with Li. (d) and (e) can be prepared by ?SiH addition to HC?C? Si? compounds (cat. H₂PtCl₆ · 6 H₂O). With Br₂ (a) yields (f). whereas (b) yields the trans compound (g). The subsequent reactions of (f) and (g) with Br₂ and their decomposition via β-elimination to (i) (j) are reported. Both (a) and (b) react with HBr to (h), changing the size of the ring in the case of (b). (h) decomposes via β-elimination. HSiCl₃ and HSime₂Br addition to (a) yields 1,1,2-trisila-ethane derivates. All intermediate compounds of these syntheses and their NMR data are given.     

Bildung siliciumorganischer Verbindungen. LVIII. Die Synthese eines Carbosilans mit Propellan-Struktur

Formation of Organosilicon Compounds. LVIII. Synthesis of a Carbosilane with Propellane Structure 1 (· ? C resp. CH₂; x ? Si(CH₃)₂ resp. Si) is formed by a coupling reaction of BrSi(CH₂? Sime₂? CH₂? Sime₂Br)₃ 2 with CCl₄ and Li. The reaction of C₆H₅me₂Si? CH₂Li with Clme₂Si? CH₂Br leads to C₆H₅me₂Si? CH₂? Sime₂? CH₂Br. Metallation with lithium and succeeding reaction with Cl₃SiC₆H₅ produces compound C₆H₅Si(CH₂? Sime₂? CH₂? Sime₂C₆H₅)₃, which than forms 2 by cleavage with bromine.     

Bildung siliciumorganischer Verbindungen. XXXI. Synthese des Brme2Si?CH2?Sime2?CC?Sime2?CH2-Sime2Br und dessen Abbau mit HBr

The synthesis of C₆H₅me₂Si? CH₂? Sime₂? C?C? Sime₂? CH₂? Sime₂C₆H₅ (a) is described, which forms Brme₂Si? CH₂? Sime₂? C?C? Sime₂? CH₂-Sime₂Br(b) with HBr. The reaction of (b) with HBr (1–4 moles at ?78°C) yields Brme₂Si? CH₂? Sime₂Br, as well as 1,2-dibromo-ethane (main products) and Brme₂Si? CH₂/? Sime₂CH = CHBr, Brme₂Si? CH₂? Sime₂CH₂? CHBr₂.     

Bildung siliciumorganischer Verbindungen. 84 [1]. Synthese und thermische Umlagerung von verschieden substituierten linearen und cyclischen Silanen

Formation of organosilicon compounds. 84. Synthesis and thermal rearrangement of some substituted linear and cyclic silanes In part IR we report on the synthesis of substituted silanes, and in part II on their thermal rearrangement. I: me₃i--Sime₃(me = CH₃) is formed by dropwise addition of THF to a suspension of Li powder in me₃SiCl; yield ～ 80%. The mixture me₃Si--Sime₂Cl, me₃SiCl, Li powder and THF reacts analogously to form me₂Si(Sime₃)₂; yield 80%. By the same type of reaction the following compounds are obtained: compound 1 from Brme₂Si? CH₂? Sime₂Br, 1 from Brme₂Si? CH₂? Sime₂Br, 2 from Brme₂Si? Sime₂? CH₂? Sime₂Br 16 and 3 from Bret₂Si? CH₂? CH₂? Siet₂Br (et = C₂H₅). 2 decomposes during its isolation from THF. 16 is formed from phme₂Si? Sime₂? CH₂? Sime₂ph 17 (ph = C₆H₅) by reaction with HBr, 17 either from phme₂SiLi and Clme₂SiCH₂Cl or from phme₂Si? Sime₂Br and LiCH₂? Sime₂ph. II: me₂Si(Sime₃)₂ rearranges at 440 °C (56 h) with insertion of the CH₂ group (Si? H formation) into the Si? Si bond and the formation of me₃Si? Sime₂? CH₂? Sime₂H, me₂HSi? CH₂? Sime₂? CH₂? SiHme₂, and me₃Si? CH₂? Sime? CH₂? Sime₂H. 1 reacts analogously. Methylated halogenated disilanes like Brme₂Si? Sime₂Br react with separation of: Sime₂ and its insertion into the Si-halogen bond to form trisilanes. Different from both are the phenylated derivatives, though phme₂Si? Sime₂ph still forms phme₂Si? Sime₂? Sime₂ph. 3 reacts with separation of C₂H₄, formation of the Si? H group and insertion of C₂H₄ into the Si? Si bond.     

Bildung siliciumorganischer Verbindungen. 85 [1]. Bildung,Reaktionen und Struktur des 1,1,3,3-Tetramethyl-2,4-bis(trimethylsilyl)-1,3-disilabicyclo[1, 1, 0]butans

me₃Si? CCl₂?Sime₂Cl (me ? CH₃) läßt sich mit n-buLi (bu ? C₄H₉) bei–100°C (Lösungsmittel THF/Äther) in me₃Si? CCl(Li)? Sime₂Cl a überführen. das mit meJ me₃Si? CClme? Sime₂Cl bildet. Wird a in Abwesenheit eines Abfangreagenzes langsam erwärmt, so bildet sich unter Abspaltung von LiCl (Cl aus der SiCl-Gruppe) über eine reaktive Zwischenstufe des Bicyclobutans b . Die Struktur von b ist durch NMR-Untersuchung, Röntgenstrukturanalyse und Abbaureaktionen gesichert. Mit HBr bzw. CH₃OH werden die Si? C-Bindungen der Dreiringe in b gespalten, so daß sich me₃Si? CH₂? C(Sime₂X)₂Sime₃ (X ? Br, OCH₃) bildet. Formation of Organosilicon Compounds. 85. Formation, Reactions, and Structure of 1,1,3,3-Tetramethyl-2,4-bis(trimethylsilyl)-1,3-disilabicyclo[1, 1, 0]butane me₃Si? CCl₂? Sime₂Cl (me ? CH₃) with n-buLi (bu ? C₄H₉) at –100°C (solvent: THF/ether) yields me₃Si? CCl(Li)? Sime₂Cl a , which forms me₃Si? CClme? Sime₂Cl with meI. By warming a slowly in absence of any trapping reagent the bicyclobutane b is obtained via a reactive intermediate under elimination of LiCl (Cl from the SiCl group). The structure of b is established by nmr investigations, X-ray structure determination and chemical derivatisation.     

Bildung siliciumorganischer Verbindungen. 88. Zur SiH-Addition von 1,3,5-Trisilacyclohexanen an silylierte Alkine

Formation of Organosilicon Compounds. 88. SiH-Addition of 1,3,5-Trisilacyclohexanes to Silylalkynes Catalyzed by means of H₂PtCl₆ the SiH addition of 1,1,3,3,5-pentamethyl-1,3,5-trisilacyclohexane to HC?C? Sime₂CH₂Cl, and of 1,1,3,3,5-pentaphenyl-1,3,5-trisilacyclohexane to HC?C? Sime₂CH₂Br yields a and b , or c and d , resp. (Formulae see Inhaltsübersicht), whereas 1,3,5-trisilacyclohexanes with more SiH groups preferrably yield polymers. The c/d ratio is strongly governed by the solvent: 38% c in n-hexane, 72% c in CCl₄/cyclohexane. Treatment of c and d with HCl/AlCl₃ under cleavage of all of the phenyl groups, addition of HCl to the vinyl group and subsequent β-elimination leads to (Cl₂Si? CH₂)₃ ClSime₂? CH₂Br and compound e , whereas HBr at ?78°C only cleaves one phenyl group per Si atom.     

Bildung siliciumorganischer Verbindungen. 89. Selektive Photobromierung von Si-methylierten Carbosilanen

Formation of Organosilicon Compounds. 89. Selective Photobromination of Si-methylated Carbosilanes A selective photobromination of the C atoms in the skeleton of Si-methylated carbosilanes is reported. (me₃Si? CH₂)₂Sime₂ reacts to me₃Si? CBr₂? Sime₂? CH₂? Sime₃ in good yields (me = CH₃); the second CH₂ group is considerably slower brominated. Photobromination of (me₂Si? CH₂)₃ consecutively yields a and b . Also from (me₂Si? CH₂)₄ the derivative with one CBr₂ group is accessible. Bromination of tertiary CH groups is highly preferred; this is shown by the selective formation of c . The C-bromination of SiBr-substituted carbosilanes is significantly more difficult; nevertheless (Brme₂Si)₂CH₂ selectively forms (Brme₂Si)₂CBr₂. Brme₂Si? CH₂? Sime₂? CH₂? Sime₃ forms Brme₂Si? CH₂? Sime₂? CBr₂? Sime₃, i. e., only the CH₂ group non-adjacent to SiBr is attacked. The formation of CHBr groups could not be detected. Higher temperatures and longer reaction times increase the formation of polymers.     

Bildung siliciumorganischer Verbindungen. 86. Si-phenylierte und butylierte 1,3,5-Trisilacyclohexane

Formation of Organosilicon Compounds. 86. Si-phenyl and Si-butyl Substituted 1,3,5-Trisilacyclohexanes By treating (BrHSi? CH₂)₃ with phMgBr or t-buLi, resp., and subsequent separation of the isomers, the pure cis-cis substituted 1,3,5-trisilacyclohexanes I are accessible which yield II (Formula see Inhaltsübersicht) by reaction with Br₂. (F₂Si? CH₂)₃ 8 can be transferred into (ph₂Si? CH₂)₃ 7 with phLi. With HCl/AlCl₃ 7 forms (Cl₂Si? CH₂)₃, whereas even with an excess of Br₂ it only yields (phBrSi? CH₂)₃. Cleavage of 7 with one equivalent of Br₂ yields (H₂C? Si)₃ph₅Br 14, which with LiAlH₄ forms (H₂C? Si)₃ph₅H 10. 10 is not so easy to obtain via (H₂C? Si)₃ph₅F 9 from the reaction of 8 with 5 equivalents of phLi. All of the SiH and SiBr groups in I and II, resp., occupy axial positions as well as the Br atom in 14 the H atom at Si in 10 and the F atom in 9.     

Die Kristallstruktur von (PPh4)2[Mo2(O2C?Ph)4Br2] · 2 CH2Br2

Crystal Structure of (PPh₄)₂[Mo₂(O₂C? Ph)₄Br₂] · 2 CH₂Br₂ The title compound, prepared by the reaction of Mo₂(O₂C? Ph)₄ with PPh₄Br and PPh₄N₃, respectively, under the assistance of CH₂Br₂, was characterized by an X-ray structure determination. Space group P2₁/n, Z = 2, R = 0.074 (5261 independent observed reflexions). The lattice dimensions are at ?70°C: a = 1562.9, b = 1406.2, c = 1662.1 pm, β = 94.11°. the compound consists of PPh₄^⊕ ions, CH₂Br₂ molecules, and centrosymmetric anions [Mo₂(O₂C? Ph)₄Br₂]^2?. The axis Br? Mo?Mo–Br is nearly linear (bond angle 175.6°) with bond lengths MoMo = 212.3 pm and Mo? Br = 303 pm, corresponding with a weak electrostatic Mo? Br bond. In the FIR spectrum the Mobr stretching vibration is found at 85 cm^?1, which corresponds with the low value of the force constant of 0.24 N · cm^?1.     

Bildung siliciumorganischer Verbindungen. LVI. Reaktionen Si- und C-chlorierter 1,3,5-Trisilapentane mit CH3MgCl

Formation of Organosilicon Compounds. LVI. Reactions of Si- and C-Chlorinated 1,3,5-Trisilapentanes with CH₃MgCl (Cl₃Si? CCl₂)₂SiCl₂ (1) reacts with an excess of meMgCl (me = CH₃) forming me₃Si? C?C? Sime₃ (2), Sime₄, H₂C?C(Sime₃)[CH(Sime₃)₂] (3) as main products and (me₃Si)₂C? CH(Sime₃) and as by-products. The cleavage reaction of (1) to (2) and (3) does not occur when the meMgCl-concentration is lowered. The reaction is started by the formation of a GRIGNARD reagent at a CCl-group in compound (1). Cl₃Si? CCl₂? SiCl₂? CH₂? SiCl₃ forms with ; me₃Si? CCl₂? SiCl₂? CHCl? SiCl₃ forms (me₃Si)₂C?CH(Sime₃). A reaction sequence is given.     

Zur Bildung von Disilylphosphino-Element-Verbindungen des C,Si, P

The Formation of Disilylphosphino-Element Compounds of C, Si, P The reactions of (me₃Si)₂PLi · OR₂ a (OR₂ = 1 monoglyme or 2 THF; me = CH₃) with CH₃Cl, CH₂Cl₂, ClCH₂CH₂Cl and ClCH₂? C₆H₅ give the compounds (me₃Si)₂Pme, (me₃Si)₂P? CH₂? P(Sime₃)₂, (me₃Si)₂P? CH₂CH₂Cl, (me₃Si)₂P? CH₂CH₂? P(Sime₃)₂ and (me₃Si)₂P? CH₂C₆H₅ respectively. In the same manner a reacts with me₂SiCl₂ in a molar ratio 1:1 to (me₃Si)₂P? Sime₂Cl and in a molar ratio 2:1 to (me₃Si)₂P? Sime₂? P(Sime₃)₂ b . The compound b decomposes to [me₃SiP? Sime₂]₂ and (me₃Si)₃P at 220°C. In the reactions of a with ClP(C₆H₅)₂ and ClPme₂ the compounds (me₃Si)₂P? P(C₆H₅)₂ and (me₃Si)₂P? Pme₂, respectively, are obtained. a reacts with HgCl₂ to (me₃Si)₂P? P(Sime₃)₂. (me₃Si)₃P can be cleaved with ClP(C₆H₅)₂ and ClPme₂ yielding (me₃Si)₂P? P(C₆H₅)₂ and (me₃Si)₂P? Pme₂, respectively. The ¹H- and ³¹P-n.m.r. and mass spectroscopic data are reported.     

Bildung siliciumorganischer Verbindungen. 74. Synthese und NMR-Spektren von Si-methylierten und -chlorierten 2,2-Dichloro-1,3-disilapropanen und 2-Methyl-2-chloro-1,3-disilapropanen

Formation of Organosilicon Compounds. 74. Synthesis and NMR-Spectra of Si-methylated and -chlorinated 2,2-Dichloro-1,3-disilapropanes and 2-Methyl-2-chloro-1,3-disilapropanes The compounds me₃Si? CCl₂? Sime_nCl_3?n (n = 1–3; me = CH₃) are synthesized by reaction of me₃Si? CCl₂Li (formed from me₃Si? CCl₂H with n-buLi, bu = butyl) with the appropriate methylchlorosilanes. The compounds Clme₂Si? CCl₂? Sime_nCl_3?n are obtained by analogous reactions of (C₆H₅)me₂Si? CCl₂Li, cleavage of the Si-phenyl group with bromine and conversion of the Si? Br to the Si? Cl group with HCl in PCl₃. The 2-methyl-2-chloro-1,3-disilapropanes are synthesized by lithination of the CCl₂ group of 2,2-dichloro-1,3-disilapropanes, followed by reaction with meI. (Clme₂Si)₂CmeCl is obtained from (C₆H₅me₂Si)₂CCl₂ by reaction with n-buLi to (C₆H₅me₂Si)₂ CClLi, which forms (C₆H₅me₂Si)CClme with meI. Cleavage with bromine to (Brme₂Si)₂CClme and reaction with HCl/PCl₃ leads to the expected compound. The influence of the substitution on the ¹H, ¹³C and ²⁹Si NMR spectra is investigated.     

Negative ion chemical ionization mass spectrometry—binding of molecules to bromide and iodide anions

The analytical potential of negative ion chemical ionization (NICI) mass spectrometry utilizing dibromodifluoro-methane (CF₂Br₂) and iodomethane (CH₃I)/methane (CH₄) as reagent gases is examined. The NICI mass spectrum of CF₂Br₂ contains Br^?, [HBr₂]^? and [CF₂Br₃]^? anions. Weak acids (i.e. those acids with approximately ΔH°_(acid) values between 1674 and 1464 kJ mol^?1) react with Br^? to produce minor yields of the hydrogen?bonded bromide attachment [MH + Br]^? anion or are unreactive. Strong acids (i.e. those acids with approximately ΔH°_(acid) > 1464 kJ mol^?1) produce primarily [MH + Br]^? anions with a minor yield of proton transfer [M ? H]^? anion. The NICI spectrum of CH₃I/CH₄ is dominated by I^?. Weak acids react with I^? to yield minor amounts of [MH + 1]^? or are unreactive. Strong acids produce only [MH + l]^? anions. From a consideration of the gas-phase basicity of the halide anion and the binding energy of the hydrogen-bonded halide attachment adduct, thermochemical data are used as a potential guide to rationalize or predict the ions observed in NICI mass spectra.     

Bildung siliciumorganischer Verbindungen. 66. (H2Si?CH2)2 und Si-substituierte Derivate

Formation of Organosilicon Compounds. 66. (H₂Si? CH₂)₂ and Si-substituted Derivatives (H₂Si? CH₂)₂ 1 is formed in the reaction of (Cl₂Si? CH₂)₂ with LiAlH₄. In 1 , the halogenation of the SiH bond is so much preferred compared to the ring cleavage reaction, that 1 reacts with Cl₂ or Br₂ to form successively all compounds form 1-monochlor-1,3-disilacyclobutane to (X₂Si? CH₂)₂ (X = Cl, Br). The stability of the 1,3-disilacyclobutane skeleton towards HBr or Br₂ increases as the electronegativity of the Si-substituents increases. Thus, (Cl₂Si? CH₂)₂ is cleaved neither by HBr nor by Br₂, whereas e. g. [H(C₆H₅)Si? CH₂]₂ reacts to [Br(C₆H₅)Si? CH₂]₂ with Br₂, but yields meH(C₆H₅)Si? CH₂? SiBr(C₆H₅)H (me = CH₃) with HBr. In [me(C₆H₅)Si? CH₂]₂, the four-membered ring is cleaved by Br₂ as well as by HBr. The ¹H-, ²⁹Si- and ¹³C-n.m.r. data are reported.     

(CH3)2SBr2 – einige Reaktionen und Strukturen

(CH₃)₂SBr₂ – Reactions and Structures (CH₃)₂SBr₂ ( 1 ) is a donor acceptor complex (8-S-3 + 10-Br-2) which reacts with (CH₃)₂S(?O)NSi(CH₃)₃ to yield [(CH₃)₂S(O)?N? S(CH₃)₂]⁺Br^? ( 2 ). With SbBr₃ (CH₃)₂SBr⁺SbBr₄^? ( 3 ) can be isolated. 1 crystallizes monoclinic in the space group P2₁/c with a = 733.8, b = 734.2, c = 1132.7 pm, β = 92.8° and Z = 4. 2 crystallizes in the orthorhombic space group Pnma with a = 967.2, b = 793.3, c = 1168.3 pm and Z = 4. The SBr and BrBr force constants of 1 are compared with those of S₂Br₂, 3 and Br₂ resp. The nmr and mass spectra of 1 and 2 are communicated.     

Bildung siliciumorganischer Verbindungen. 70 [1]. Reaktionen Si-fluorierter 1,3,5-Trisilapentane mit CH3MgCl und LiCH3

Formation of Organosilicon Compounds. 70. Reactions of Si-fluorinated 1,3,5-Trisilapentanes with CH₃MgCl and LiCH₃ F₃Si? CCl₂? SiF₂? CH₂? SiF₃ 3 reacts with meMgCl. (me = Ch₃ starting with a Si-methylation and not with a C-metallation as in the corresponding Si- and C-chlorinated compounds, e. g. (Cl₃Si? CCl₂)₂SiCl₂ [2]. A CCl-hydrogenation is observed too, which in the case of F₃Si? CCl₂? SiF₂? CHCl? SiF₃ 4 gives meS₃Si? CCl₂? Sime₂? CH₂? Sime₃. (F₃Si? CCl₂)_{2 5} reacts with meMgCl to form preferentially 1,2-Disilapropanes by cleaving a Si? Cbond. The isolation of F₃Si? CCl₂H and meF₂Si? CCl₂? SiF₂me allows to locate the bond where 5 is cleaved at the beginning of the reaction. With meLi 5 reacts to form mainly me₃Si? C?C? Sime₃, showing that in the reaction of meLi, being a stronger reagent than meMgCl, and 5 a C-metallation occurs, following the same mechanism as in the reaction with (Cl₃Si? CCl₂)₂)SiCl₂ [2]. The reaction conditions for the synthesis of Si-fluroinated and C-chlorinated 1,3,5-Trisilapentanes in a 0.1 mol scale are reported. N.m.r. data of all investigated compounds are tabulated.     

Bildung siliciumorganischer Verbindungen. 67. Untersuchungen zur metallorganischen Synthese Si-methylierter und C-chlorierter Carbosilane über Chlorcarbenoide

Formation of Organosilicon Compounds. 67. Studies of Metallorganic Synthesis of Si-methylated and C-chlorinated Carbosilanes Using Chlorocarbenoids Synthesis and reactions of C₆H₅me₂Si? CCl₂H (A), (H₅C₆me₂Si)₂CCl₂ (B), and me₂Si(CCl₂H)₂ (C) were investigated in order to find conditions for the synthesis of C-functional carbosilanes via chlorocarbenoids. (A) and (B) react with n-butyl-Li(buLi) (?100°C/THF/ether/pentane) yielding H₅C₆me₂Si? CCl₂Li and (H₅C₆me₂Si)CClLi, respectively. These lithium reagents form (B) and(H₅C₆me₂Si)₃CCl with H₅C₆me₂SiCl. In the reaction of (H₅C₆me₂Si)₃CCl with lithium (H₅C₆me₂Si)₃CLi (D) is obtained. (D) forms with H₂O/HCl the compound (H₅C₆me₂Si)₃CH which is cleaved by HBr yielding (Brme₂Si)₃CH. (C) gives LiCCl₂? Sime₂(CCl₂H) with buLi (molar ratio 1:1) in a low temperature reaction. Clme₂Si? CCl₂? Sime₂(CCl₂H) is formed in the reaction of LiCCl₂? Sime₂? CCl₂H with Sime₂CCl₂ (yield >90%). Reacting (C) and buLi (1:3) and treating this solution with Sime₂CI₂ gives (ClSime₂)₂C?CH Sime₂Cl (>85%) via a monosilacyclopropane intermediate. In the inverse reaction, if (C) is added to buLi, (HCCl₂)me₂SiC?Sime₂(CCl₂H) is one of the isolated reaction products. If buLi is added to (C) (2:l) and this solution is treated with Sime₃Cl, compounds me₃Si? CCL₂? Sime₂? CCL₂H, me₃Si? CClH? Sime₂(CCl₂H), (me₃Si? CC1₂)₂Sime₂, me₃Si? CHCI? Sime₂? CC1₂? Sime₃ are isolated. The same products were obtained in the reaction of me₃Si? CCl₂? Sime₂? CCl₂H with buLi and me₃SiCl.     

Experimental and Computational Probes of the Nature of Halogen Bonding: Complexes of Bromine‐Containing Molecules with Bromide Anions

The nature of halogen bonding is examined via experimental and computational characterizations of a series of associates between electrophilic bromocarbons R? Br (R? Br=CBr₃F, CBr₃NO₂, CBr₃COCBr₃, CBr₃CONH₂, CBr₃CN, etc.) and bromide anions. The [R? Br, Br^?] complexes show intense absorption bands in the 200–350 nm range which follow the same Mulliken correlation as those observed for the charge‐transfer associates of bromide anions with common organic π‐acceptors. For a wide range of the associates, intermolecular R? Br???Br^? separations decrease and intramolecular C? Br bond lengths increase proportionally to the Br^?→R? Br charge transfer; and the energies of R? Br???Br^? bonds are correlated with the linear combination of orbital (charge‐transfer) and electrostatic interactions. On the whole, spectral, structural and thermodynamic characteristics of the [R? Br, Br^?] complexes indicate that besides electrostatics, the orbital (charge‐transfer) interactions play a vital role in the R? Br???Br^? halogen bonding. This indicates that in addition to controlling the geometries of supramolecular assemblies, halogen bonding leads to electronic coupling between interacting species, and thus affects reactivity of halogenated molecules, as well as conducting and magnetic properties of their solid‐state materials.     

An FTIR spectroscopic study of the reactions Br + CH3CHO → HBr + CH3CO and CH3C(O)OO + NO2 ⇌ CH3C(O)OONO2 (PAN)

Based on an FTIR-product study of the photolysis of mixtures containing Br₂? CH₃CHO and Br₂? CH₃CHO? HCHO in 700 torr of N₂, the rate constant for the reaction Br + CH₃CHO → HBr + CH₃CO was determined to be 3.7 × 10^?12 cm³ molecule^?1 s^?1. In addition, the selective photochemical generation of Br at λ > 400 nm in mixtures containing Br₂? CH₃CHO? ¹⁴NO₂ (or ¹⁵NO₂)? O₂ was shown to serve as a quantitative preparation method for the corresponding nitrogen-isotope labeled CH₃C(O)OONO₂ (PAN). From the dark-decay rates of ¹⁵N-labeled PAN in large excess ¹⁴NO₂, the rate constant for the unimolecular reaction CH₃C(O)OO¹⁵NO₂ → CH₃C(O)OO + ¹⁵NO₂ was measured to be 3.3 (±0.2) × 10^?4 s^?1 at 297 ± 0.5 K.     

Secondary interactions in 4‐bromo‐N,N‐dimethylanilinium bromide

The crystal packing of the title compound, C₈H₁₁BrN⁺·Br^?, involves three types of secondary interaction: a classical N—H?Br^? hydrogen bond, a `weak' but short C—H?Br^? interaction (normalized H?Br distance of 2.66 Å) and a cation–anion Br?Br contact of 3.6331 (4) Å. The hydrogen bonds connect two cations and two anions to form rings of graph set R(14). The Br?Br contacts link these rings to form layers parallel to the bc plane.