[en] The facil exchange of H₂Re₂(CO)₈ and H₂Os₃(CO)₁₀ with D₂O in the presence of Florisil chromatographic adsorbent was monitored by mass spectrometry. Owing to the possibility of an isotope effect in the ionization process and the presence of random errors in the recording system, a determination of the accuracy and precision of this analytical method was undertaken. As an extension of thermal hydrogenation synthesis, several of the compounds used in these studies were prepared by photolytic hydrogenation of Re₂(CO)₁₀

[en] This review article is largely concerned with the efforts to gather structural information on hydrogen bridge bonds with neutron diffraction data. 11 figures, 1 table

[en] The compound [(Ph₃P)₂N]⁺²[H₂W₂(CO)₈]^2- has been synthesized in 65% yield from the reaction of [(Ph₃P)₂N]⁺[BH₄]^- with [(Ph₃P)₂N]⁺[W(CO)₅(I)]^- in refluxing tetrahydrofuran. The dianion reacts with BH₃THF in THF to produce [(Ph₃P)₂N]⁺[W(CO)₄(BH₄)]^- in 60% yield. The structure of [(Ph₃P)₂N]⁺₂[H₂W₂(CO)₈]^2- has been studied with x-ray and neutron diffraction techniques at room temperature and 28 K, respectively. The [H₂W₂(CO)₈]^2- anion has approximately D_2h symmetry with a planar W(μ-H)₂W bridge, confirming the earlier x-ray results by Churchill and co-workers on (Et₄N]⁺₂[H₂W₂(CO)₈]^2-. In the [(Ph₃P)₂N]⁺ salt, the anions are situated on crystallographic inversion centers, and distances and angles in the W(μ-H)₂W core are as follows: W-H = 1.920 (3) and 1.933 (2) A, W...W = 3.010 (2) A, H...H = 2.405 (3) A, W-H-W = 102.7 (1)⁰, H-W-H = 77.3 (1)⁰, and H-W-W = 38.78 (6) and 38.78 (6)⁰. The two bridging H atoms are displaced slightly from the intersections of the trans CO-metal vectors in the direction of the metal-metal axis. The [(Ph₃P)₂N]⁺ cation has the usual bent P-N-P configuration, but the phenyl rings are in an uncommon staggered conformation. Crystal data from the neutron diffraction analysis of [(Ph₃P)₂N]⁺₂[H₂W₂(CO)₈]^2- at 28 K: space group P anti 1^-; a = 12.949 (1), b = 13.871 (2), c = 11.000 (1) A; α = 110.828 (8), β = 105.788 (9), γ = 69.334 (8)⁰; V = 1703.4 (4) A³; Z = 1. Final agreement factors were R(F) = 0.027 for 5206 neutron reflections with I greater than or equal to sigma(I) and R(F) = 0.040 for 4238 x-ray reflections with I greater than or equal to 3 sigma(I). 5 figures, 7 tables