1,3,4,6-Tetramethyl-1,4-dihydro-1,2,4,5-tetrazine, C_6H_(12)N_4

M_r =140∙19, monoclinic, P2_1/n, a = 10∙612(3), b=6∙820(1), c= 10∙975 (2) Å, β=95∙31(2)°, V=790.9(5) Å^3, Z=4, D_m=1.13(5) (flotation), D_x = 1∙177 g cm^(-3), Mo Kα, λ = 0.71073 Å, μ= 0.848 cm^(-1), F(000) = 304, T= 295 K, R = 0∙077 for 704 observed reflections. This potentially antiaromatic or homoaromatic ring system has a flattened boat conformation with both N-methyls in equatorial positions. Bond angles and distances (excluding H's) predicted to be symmetry equivalent exhibit variations of 0.002-0.014 Å and 0.0-2.0°. Substantial delocalization of the electron lone pairs of N(1) and N(4) is found

Stereochemical studies on protonated bridgehead amines. ^1H NMR determination of cis and trans B-C ring-fused structures for salts of hexahydropyrrolo [2,1-a] isoquinolines and related C ring homologs. Capture of unstable ring-fused structures in the solid state

Acid-addition salts of tricyclic isoquinolines 2a/b, 3a/b, 4a-4c, 5, 6a/b, 7, 8a/b, 9a/b, and 17a/b were studied by high-field ^1H NMR in CDCl_3 solution. Cis (e.g., 14 and 15 in Figure 1) and trans (e.g., 13)B-C ring-fused structures were identified by using the vicinal ^3J(CH-NH) coupling constants, which demonstrate a Karplus-like behavior. In some cases, we initially observed a trans form, which converted to a cis A form by N H proton exchange. For 4c.HBr, the exchange process was slowed by addition of trifluoroacetic acid. In many cases, cis A and cis B structures were preferred in solution. The pendant phenyl group exerted a strong influence on the preferred solution structure. Observation of the initial, unstable trans-fused structures was related to their capture in the solid state and release intact on dissolution. X-ray diffraction was performed on the HBr salts of 2a (B-C cis), 2b (B-C cis), and 4c (B-C trans). The result for 4c.HBr confirmed the connection between the initial trans form in solution and the solid state. For 17b.HCI two conformers, associated with hindered rotation about the bond connecting the 2,6-disubstituted phenyl group to the tricyclic array, were detected at ambient probe temperature; however, rotamers were not observed for either of the two forms (trans and cis A) of 17a.HBr. Two conformers were also found for 16b.HBr. Temperature-dependent behavior was recorded in the ^1H NMR spectra of 17b.HBr and 16b.HBr; the activation free energy for interconversion of conformers was estimated to be in the vicinity of 17 kcal/mol for the former and 14-15 kcal/mol for the latter. The ^1H NMR spectrum of butaclamol hydrochloride (20.HC1), a potent neuroleptic agent, in Me_2SO-d_6 revealed two species in a ratio of 81:19, which were assigned as trans and cis A forms, respectively. ^1H NMR data for various free bases are also presented and discussed. Empirical force field calculations on three model hydrocarbons are discussed from a perspective of finding an explanation for the configurational/conformational behavior of the bridgehead ammonium salts. Diverse literature examples of structures for protonated bridgehead amines are also discussed. A tentative rationale is suggested for the preference of cis A forms in some protonated tetrahydroisoquinoline derivatives

The impact of emotional well-being on long-term recovery and survival in physical illness: a meta-analysis

This meta-analysis synthesized studies on emotional well-being as predictor of the prognosis of physical illness, while in addition evaluating the impact of putative moderators, namely constructs of well-being, health-related outcome, year of publication, follow-up time and methodological quality of the included studies. The search in reference lists and electronic databases (Medline and PsycInfo) identified 17 eligible studies examining the impact of general well-being, positive affect and life satisfaction on recovery and survival in physically ill patients. Meta-analytically combining these studies revealed a Likelihood Ratio of 1.14, indicating a small but significant effect. Higher levels of emotional well-being are beneficial for recovery and survival in physically ill patients. The findings show that emotional well-being predicts long-term prognosis of physical illness. This suggests that enhancement of emotional well-being may improve the prognosis of physical illness, which should be investigated by future research

Precision bond lengths for Rydberg Matter clusters KN (N = 19, 37, 61 and 91) in excitation levels n = 4 - 8 from rotational radio-frequency emission spectra

Clusters of the electronically excited condensed matter Rydberg Matter (RM) are planar and six-fold symmetric with magic numbers N = 7, 19, 37, 61 and 91. The bond distances in the clusters are known with a precision of +- 5% both from theory and Coulomb explosion experiments. Long series of up to 40 consecutive lines from rotational transitions in such clusters are now observed in emission in the radio-frequency range 7-90 MHz. The clusters are produced in five different vacuum chambers equipped with RM emitters. The most prominent series with B = 0.9292 +- 0.0001 MHz agrees accurately with expectation (within 2%) for the planar six-fold symmetric cluster K19 in excitation level n = 4. Other long series agree even better with K19 at n = 5 and 6. The ratio between the interatomic distance and the theoretical electron orbit radius (the dimensional ratio) for K19 in n = 4 is found to be 2.8470 +- 0.0003. For clusters K19 (n = 6) and K37 (n = 7 and 8) the dimensional ratio 2.90 is the highest value that is found, which happens to be exactly the theoretical value. Clusters K61 and K91 in n = 5 and 6 have slightly lower dimensional ratios. This is expected since the edge effects are smaller. Intensity alternations are observed of approximately 7:3. The nuclear spins interact strongly with the magnetic field from the orbiting electrons. Spin transitions are observed with energy differences corresponding accurately (within 0.6%) to transitions with apparent total (delta)F = -3 at excitation levels n = 5 and 6. The angular momentum coupling schemes in the clusters are complex but well understood.Comment: 37 pages, 14 figure