The rates of deprotonation, MH+ + B + M + BH+ (M = 1, 2), and the rates of protonation, M + BH+ -t MH+ + B (M = 2,3,4), have been measured by Fourier transform-ion cyclotron resonance (FT-ICR) spectrometry for the increasingly sterically crowded alkyl benzenes ethylbenzene, 1; 1,3,5-trimethylbenzene (mesitylene), 2; 3,5-di-(t-butyl)toluene, 3; 1,3,5-tri(t-butyl) benzene, 4; and a series of n-bases B. In addition, the gas phase basicities of 3 and 4 were determined by proton transfer equilibrium measurements using FT-ICR.The efficiencies of deprotonation and protonation are always large (> 50%) for exoergic reactions and increase with increasing exoergicity, but never reach unit efficiency. For each of the alkylated benzenes l-4 the efficiency decreases steeply at the border between exoergic and endoergic reactions. This is the "normal" behaviour of proton transfer reactions and shows the absence of steric effects for proton transfer to and from alkylated benzenes even in the case of 3 and 4 substituted by bulky r-butyl groups, and is in complete contrast to the behaviour of t-butylated pyridines. This difference is explained by different geometries of the transition state for the proton transfer reactions in the case of the alkylated pyridines and alkylated benzenes, and by the critical role of x-complexes in proton transfer reactions of benzene derivatives.

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The reactions of the [2-2]-paracyclophane 1 and the [2-2]-metaparacyclopane 2 in the gas phase after protonation by CI(CH) or CI(I-CH) were studied by FT-ICR mass spectrometry. The ions CH produced in the external ion source of the FT-ICR instrument were transferred into the ICR cell containing the neutral reactant, and the reactions were analyzed measuring the efficiency of the transfer of a proton to a series of bases with known proton affinity and gas phase basicity as well as the efficiency of the ion-molecule reaction with ethyl vinyl ether. Both reaction types show that the ions CH produced by chemical ionization (CI) consist of two sets of isomeric ions A and B which exhibit distinctly different behavior on deprotonation and of the reaction with ethyl methyl ether. Isomer(s) A (about 65% of the ion population) react efficiently with this vinyl ether by an addition/elimination process typical of primary and secondary benzylic carbenium ions, while isomer B (about 35% of the ion population) undergoes only an ineffective deprotonation by the vinyl ether. By bracketing deprotonation, it is shown that A is actually composed of two isomers A and A with slightly different proton affinity and gas phase basicity. These two ions have been identified using CA-mass spectrometry as protonated 3-phenethylstyrene (A) and protonated 4-phenethylstyrene (A). The CA-mass spectrum of the isomer B indicated that these ions CH correspond to protonated 1-(ethyl phenyl)-1-phenyl-ethene. This agrees with the rather strong basicity of the conjugated base of ions B, which results in a slow deprotonation. A protonated 1-(ethyl phenyl)-1-phenyl-ethene can arise from a protonated 2-phenethylstyrene by H- and subsequent phenyl shifts, but requires the preceding rearrangement of the protonated [2.2]-paracyclophane into the protonated isomer "[2.2]-orthocyclophane" - the 1,5-dibenzocyclooctadiene. The possibility of such a deep-sited rearrangement was studied by the computation of the relevant reaction routes applying DFT-methods at the level B3LYP/6-311+g(3d,2p)//B3LYP/3-21g) to analyze the reaction mechanisms.

Die diamagnetischen (Ausnahme 1a) Verbindungen (PPh4)2[Fe(WS4)2(NO)] (1a), (PPh4)2[Fe(WS4)(NO)2] (2a), (PPh4)2[Co(WS4)2(NO)] (3a) und (PPh4)[Co(WS4)(NO)2] (4a) wurden durch UV/VIS‐ und IR‐Spektroskopie, magnetische Messungen sowie durch vollständige Röntgenstrukturanalyse charakterisiert. 1 a: P1, a = 912,3(2), b = 1052,7(2) c = 1340,7(3) pm, α = 87,16(2), β = 84,15(2), γ = 84,90(2)°, V = 1274,7 · 106 pm3, Z = 1; R = 0,088 für 2284 unabhängige Reflexe (F0 > 3,92 σ(F0)); 2a: P1, a = 974,1(2), b = 1278,6(3), c = 1986,2(4) pm, α = 103,71(2), β = 104,94(2), γ = 95,55(2)°, V = 2289,0 · 106 pm3, Z = 2; R = 0,075 für 4490 unabhängige Reflexe (F0 > 3,92 σ(F0)); 3a: P1, a = 908,8(9), b = 1049,4(10), c = 1342,5(14) pm, α = 87,21(8), β = 83,99(8), γ = 85,26(8)°, V = 1267,9 · 106 pm3, Z = 1; R = 0,074 für 3145 unabhängige Reflexe (F0 > 3,92 σ(F0)); 4a: P1, a = 957,2(2), b = 1074,6(3), c = 1394,8(3) pm, α = 100,71(2), β = 90,55(3), γ = 93,68(2)°, V = 1406,5 · 106 pm3, Z = 2; R = 0,068 für 3599 unabhängige Reflexe (F0 > 3,92 σ(F0)). Für (NEt4)[Co(MoO2S2)(NO)2] werden früher nicht mitgeteilte kristallographische Daten angegeben.