Melem C6N7(NH2)3 was shown to form a variety of adduct phases and salts. Salts of melem can be yielded by reaction of melem with strong acids. We investigated the reaction of melem with methylsulfonic acid, thus identifying two new melemium salts with formulas HC6N7(NH2)3H2C6N7(NH2)3(SO3Me)3·H2O (1) and H2C6N7(NH2)3(SO3Me)2·H2O (2), respectively. The structures of both compounds were elucidated using single‐crystal XRD compound 1: (P\bar{1} no. 2, Z = 2, a = 10.096(2), b = 12.865(3), c = 13.369(3) Å, α = 63.28(3), β = 81.19(3), γ = 72.92(3)°, V = 1461.4(7) Å3) compound 2: (P21/n, no. 14, Z = 4, a = 8.0757(16), b = 7.6937(15), c = 27.540(6) Å, β = 92.03(3)°, V = 1710.6(6) Å3). Both compounds are discussed in comparison to structural data from the literature of other melemium salts. We also present new synthetic approaches for the preparation of melem in larger quantities.

A great number of binary neutral phosphorus sulfides was discovered and investigated. However all stable representatives of this family of compounds adopt a polycyclic structure in contrast to their lighter homologues, the nitrogen oxides. Acyclic representatives can be stabilized by adduct formation with a nitrogen base. The bis(pyridine) adduct py2P2S5 of the unstable acyclic phosphorus sulfide P2S5 is readily obtained stirring P4S10 in pyridine at ambient temperature. X‐ray diffraction studies on single crystals of py2P2S5·0.5 py (1b) show a N2O5 like structure for the P2S5 framework. The long P–N distances of 1.86 Å indicate only weak coordination of the pyridine molecules to phosphorus. Single crystal X‐ray diffraction studies on py2P2S4.34O0.66 (2) reveal the presence of py2P2S4O (3) together with py2P2S5 in the crystal. Compound 3 contains the mixed phosphorus oxide sulfide molecule P2S4O stabilized as bis(pyridine) adduct. It is readily obtained from pyP2S5 by oxidation with KMnO4 in pyridine. The oxygen atom occupies the bridging position between the two phosphorus atoms. Quantum chemical calculations at the MPW1PW91 level of theory as well as DTA/TG thermal analyses confirm the weak coordination of the pyridine molecules in py2P2S5, py2P2S4O, and py2P2S7 to phosphorus.

The new phosphorus sulfide P(2)S(7), stabilized as the bis(pyridinium) adduct, was obtained from the reaction of P(4)S(10) and sulfur in pyridine, and could be isolated in the form of colourless block-shaped crystals which were characterized using single crystal X-ray diffraction. Coordination of pyridine is weak (d(P-N) = 187 pm) which is supported also by quantum chemical calculations.

A new rare example of a synthetic route in solution to the hexathiohypodiphosphate anion P2S64− is presented. Starting from P4S3, Li2S, and elemental sulfur in pyridine, this reaction yields yellow block‐shaped crystals of [py2Li]4[P2S6] · 2 py (1). The molecular structure of this hitherto unknown compound was determined by single crystal X‐ray diffraction and reveals a heteronorbornane skeleton within the Li4P2S6 entity.

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