Terrestrial Trapping of the Interstellar Gas, Phosphorus Nitride

The N2 analogue phosphorus nitride (PN) was the first phosphorus containing compound to be detected in the interstellar medium, however this thermodynamically unstable compound has a fleeting existence on Earth. Here, we show that reductive coupling of iron(IV) nitride and molybdenum(VI) phosphide complexes assembles PN as a bridging ligand in a structurally-characterized bimetallic complex. Reaction with C≡N^tBu releases the mononuclear complex [(N₃N)Mo-PN]⁻, N₃N = [(Me₃SiNCH₂CH₂)₃N]³⁻), which undergoes light-induced linkage isomerization to provide [(N₃N)Mo-NP]⁻, as revealed by photocrystallography. While structural and spectroscopic characterization, supported by electronic structure calculations reveal PN multiple bond character, coordination to molybdenum creates nucleophilic character at the terminal atom of the PN/NP ligands. Indeed, the linkage isomers can be trapped in solution by reaction with a Rh(I) electrophile.

Terrestrial Trapping of the Interstellar Gas, Phosphorus Nitride

The N2 analogue phosphorus nitride (PN) was the first phosphorus containing compound to be detected in the interstellar medium, however this thermodynamically unstable compound has a fleeting existence on Earth. Here, we show that reductive coupling of iron(IV) nitride and molybdenum(VI) phosphide complexes assembles PN as a bridging ligand in a structurally-characterized bimetallic complex. Reaction with C≡N^tBu releases the mononuclear complex [(N₃N)Mo-PN]⁻, N₃N = [(Me₃SiNCH₂CH₂)₃N]³⁻), which undergoes light-induced linkage isomerization to provide [(N₃N)Mo-NP]⁻, as revealed by photocrystallography. While structural and spectroscopic characterization, supported by electronic structure calculations reveal PN multiple bond character, coordination to molybdenum creates nucleophilic character at the terminal atom of the PN/NP ligands. Indeed, the linkage isomers can be trapped in solution by reaction with a Rh(I) electrophile.

Multistep Photochemical Reactions of Polypyridine-Based Ruthenium Nitrosyl Complexes in Dimethylsulfoxide

The photorelease of nitric oxide (NO·) has been investigated in dimethylsulfoxide (DMSO) on two compounds of formula [Ru(R-tpy)(bpy)(NO)](PF6)3, in which bpy stands for 2,2′-bipyridine and R-tpy for the 4′-R-2,2′:6′,2″-terpyridine with R = H and MeOPh. It is observed that both complexes are extremely sensitive to traces of water, leading to an equilibrium between [Ru(NO)] and [Ru(NO2)]. The photoproducts of formula [Ru(R-tpy)(bpy)(DMSO)](PF6)2 are further subjected to a photoreaction leading to a reversible linkage isomerization between the stable Ru-DMSO(S) (sulfur linked) and the metastable Ru-DMSO(O) (oxygen linked) species. A set of 4 [Ru(R-tpy)(bpy)(DMSO)]2+ complexes (R = H, MeOPh, BrPh, NO2Ph) is investigated to characterize the ratio and mechanism of the isomerization which is tentatively related to the difference in absorbance between the Ru-DMSO(S) and Ru-DMSO(O) forms. In addition, the X-ray crystal structures of [Ru(tpy)(bpy)(NO)](PF6)3 and [Ru(MeOPh-tpy)(bpy)(DMSO(S))](PF6)2 are presented.

Investigation of nitro–nitrito photoisomerization: crystal structure oftrans-chloridonitro(1,4,8,11-tetraazacyclotetradecane-κ4N,N′,N′′,N′′′)cobalt(III) chloride

The reaction cavity of the nitro group in the crystal of the title compound, [CoCl(NO2)(C10H24N4)]Cl, (I), was investigated to confirm that it offers sufficient free space for linkage isomerization to occur in accordance with the observed photochemical reactivity. The complex cation has crystallographic 2/msymmetry and the nitro and chloro ligands at thetranspositions are statistically disordered. The complete cyclam ligand is generated by symmetry from a quarter of the molecule. In the crystal of (I), the complex cations and Cl−ions are linked into a three-dimensional network by N—H...Cl(counter-ion) hydrogen bonds.

Investigation of nitro–nitrito photoisomerization: crystal structures of trans-{2,2′-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato}(pyridine/4-methylpyridine)nitrocobalt(III)

The reaction cavities of the nitro groups in the title compounds, trans-{2,2′-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato-κ4 O,N,N′,O′}(nitro-κN)(pyridine-κN)cobalt(III), [Co(C16H14N2O2)(NO2)(C5H5N)], (I), and trans-{2,2′-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato-κ4 O,N,N′,O′}(4-methylpyridine-κN)(nitro-κN)cobalt(III), [Co(C16H14N2O2)(NO2)(C6H7N)], (II), have been investigated to reveal that the intermolecular CMe—H...O(nitro) contacts in (II) are unfeasible for the nitro–nitrito photochemical linkage isomerization process. In (I), there are two independent complexes showing similar conformations, and the central five-membered chelate ring of the tetradentate salen ligand adopts the same absolute configuration. This is the result of pseudo-spontaneous resolution, since the configuration of the five-membered chelate ring may frequently be reversed in solution. In the crystals of (I) and (II), the molecules are linked into three-dimensional networks by C—H...O hydrogen bonds.

Investigation of nitro–nitrito photoisomerization: crystal structures of trans-bis(acetylacetonato-O,O′)(pyridine/4-methylpyridine/3-hydroxypridine)nitrocobalt(III)

The reaction cavities of the nitro groups in the title compounds, trans-bis(acetylacetonato-κ2 O,O′)(nitro)(pyridine-κN)cobalt(III), [Co(C5H7O2)2(NO2)(C5H5N)], (I), trans-bis(acetylacetonato-κ2 O,O′)(4-methylpyridine-κN)(nitro)cobalt(III), [Co(C5H7O2)2(NO2)(C6H7N)], (II), and trans-bis(acetylacetonato-κ2 O,O′)(3-hydroxypyridine-κN)(nitro)cobalt(III) monohydrate, [Co(C5H7O2)2(NO2)(C5H5NO)]·H2O, (III), have been investigated to reveal that bifurcated intermolecular C(py)—H...O,O contacts in (III) are unfeasible for the nitro–nitrito photochemical linkage isomerization process. In each structure, the pyridine ring and the Co atom lie on a crystallographic mirror plane; in (I) and (II) the nitro group lies in the same plane, whereas in (III), which crystallizes as a monohydrate, the nitro group is disordered over three orientations in a 0.672 (16):0.164 (8):0.164 (8) ratio; the water molecule of crystallization is statistically disordered over two sites adjacent to the mirror plane. In the crystals of (I) and (II), the molecules are linked into [100] chains by C—H...O hydrogen bonds, whereas the extended structure of (III) features (010) layers linked by O—H...O and C—H...O hydrogen bonds. Compounds (I) and (II) were refined as inversion twins.

Investigation of solid-state photochemical nitro–nitrito linkage isomerization: crystal structures of trans-bis(ethylenediamine)(isothiocyanato)nitritocobalt(III) salts: thiocyanate, chloride monohydrate, and perchlorate–thiocyanate(0.75/0.25)

The reaction cavities of the nitro groups in the crystals of the title compounds, trans-[Co(NO2)(NCS)(C2H8N2)2]·X, X = SCN− (I), Cl−·H2O (II), and (ClO4 −)0.75(SCN−)0.25 (III), have been investigated, revealing that the geometry of the intermolecular N—H...O hydrogen bonds in (I) is unsuitable for nitro–nitrito photo-isomerization. The common main building block of these crystal structures is a centrosymmetric pair of complex cations connected by pairwise N—H...O(nitro) hydrogen bonds forming an R 2 2(4) ring, which is a narrow diamond shape in (I) but is approximately square in (II) and (III). The structure of (I) was reported earlier [Börtin (1976). Acta Chem. Scand. A, 30, 503–506] but is described here with an improved disorder model for the thiocyanate anions and to higher precision.

Photo-induced linkage isomerization in the gas phase probed by tandem ion mobility and laser spectroscopy

Ruthenium complexes involving sulfoxide ligands can undergo linkage isomerization upon light absorption, accompanied by dramatic changes in their optical properties.