Crystal structure and optical spectroscopy of Er2[Pt(CN)4]3.21H2O and Er2[Pt(CN)4]2.SO4.11.5H2O

We have synthesized two forms of erbium tetracyanoplatinates, Er2[Pt(CN)4]3.21H2O (red form) and Er2[Pt(CN)4]2.SO4.11.5H2O (yellow form), and determined their crystal structures by X-ray diffraction. While the red form crystallizes in the orthorhombic space group Pbcn, with a = 15.4848(3) A, b = 13.8186(2) A, c = 19.07820(10) A, alpha = beta = gamma = 90 degrees, and Z = 4, the yellow form precipitates in the tetragonal space group I4cm, with a = b = 14.321(2) A, c = 13.338(3) A, alpha = beta = gamma = 90 degrees, and Z = 4. Both forms show [Pt(CN)4]2- chains but differ markedly in color and morphology. This is due to the incorporation of sulfate ions in the latter modification, leading to an increased Pt-Pt distance. The observed optical absorption and emission behavior of the title compounds is correlated with the Pt-Pt distances.     

Two pseudopolymorphic hydrates of brucine: brucine–water (1/4) and brucine–water (1/5.25) at 130 K

The structures of two pseudopolymorphic hydrates of brucine, C₂₃H₂₆N₂O₄·4H₂O, (I), and C₂₃H₂₆N₂O₄·5.25H₂O, (II), have been determined at 130 K. In both (I) and (II) (which has two independent brucine mol­ecules together with 10.5 water mol­ecules of solvation in the asymmetric unit), the brucine mol­ecules form head‐to‐tail sheet substructures, which associate with the water mol­ecules in the inter­stitial cavities through hydrogen‐bonding associations and, together with water–water associations, give three‐dimensional framework structures.     

Brucine salts of l‐α‐hydr­oxy acids: brucinium hydrogen (S)‐malate penta­hydrate and anhydrous brucinium hydrogen (2R,3R)‐tartrate at 130 K

The structures of two brucinium (2,3‐dimeth­oxy‐10‐oxostrychnidinium) salts of the α‐hydr­oxy acids l ‐malic acid and l ‐tartaric acid, namely brucinium hydrogen (S)‐malate penta­hydrate, C₂₃H₂₇N₂O₄⁺·C₄H₅O₅⁻·5H₂O, (I), and anhydrous brucinium hydrogen (2R,3R)‐tartrate, C₂₃H₂₇N₂O₄⁺·C₄H₅O₆⁻,(II), have been determined at 130 K. Compound (I) has two brucinium cations, two hydrogen malate anions and ten water mol­ecules of solvation in the asymmetric unit, and forms an extensively hydrogen‐bonded three‐dimensional framework structure. In compound (II), the brucinium cations form the common undulating brucine sheet substructures, which accommodate parallel chains of head‐to‐tail hydrogen‐bonded tartrate anion species in the inter­stitial cavities.     

Hydrogen bonding in brucinium dihydrogen citrate trihydrate at 130 K

The structure of brucinium dihydrogen citrate trihydrate (systematic name: 2,3‐dimeth­oxy‐10‐oxostrychnidinium dihydrogen citrate trihydrate), C₂₃H₂₇N₂O₄⁺·C₆H₇O₇⁻·3H₂O, has been determined at 130 K. The crystallographic asymmetric unit comprises two brucinium cations, two dihydrogen citrate anions and six water mol­ecules of solvation. The two citrate anions, which are conformationally dissimilar, associate through extensive hydrogen‐bonding inter­actions with the common undulating brucinium cation layer substructures and the water mol­ecules, forming a three‐dimensional framework polymer.     

The Hydrogen-Bonded Coordination Polymer Tetracesium Bis(5-nitroisophthalate) Heptahydrate

Abstract  

The coordination polymer complex tetracesium bis(5-nitroisophthalate) heptahydrate [Cs₄(C₈H₃NO₆)₂ (H₂O)₇] _n has been synthesized and characterized using single-crystal X-ray diffraction. Crystals are monoclinic, space group P2₁/c, with Z = 4 in a cell with dimensions a = 12.3213(3), b = 6.7557(2), c = 36.2020(9) ?, β = 90.548(2)^o. The complex is based on a repeating unit comprising four independent and different Cs coordination centres, two 6-coordinate, and two 8-coordinate [Cs–O, range 2.959(5)–3.386(5) ?], and seven water molecules, two of which are monodentate and the other five bridging, while all other oxygen atoms in the structure, including those of the nitro groups form inter-Cs bridges. Extensive water O–H···O hydrogen-bonding interactions give a three-dimensional framework. This structure represents the first of an alkali metal compound of 5-nitroisophthalic acid that has been reported.