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Synthesis and Structural Characterisation of cis ‐ and trans ‐[(hppH) 2 PtCl 2 ], [(hppH) 3 PtCl] + Cl – and Some New Salts of the [hppH 2 ] + Cation (hppH = 1,3,4,6,7,8‐Hexahydro‐2 H ‐pyrimido[1,2‐ a ]pyrimidine): The Importance of Hydrogen Bonding
Author(s) -
Wild Ute,
Roquette Pascal,
Kaifer Elisabeth,
Mautz Jürgen,
Hübner Olaf,
Wadepohl Hubert,
Himmel HansJörg
Publication year - 2008
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200700935
Subject(s) - chemistry , crystal structure , hydrogen bond , stereochemistry , ligand (biochemistry) , pyrimidine , crystallography , medicinal chemistry , molecule , organic chemistry , biochemistry , receptor
The reaction between the guanidine derivative hppH (hppH = 1,3,4,6,7,8‐hexahydro‐2 H ‐pyrimido[1,2‐ a ]pyrimidine) and K 2 PtCl 4 in H 2 O affords the salt [hppH 2 ] 2 [PtCl 4 ], which reacts further with Li(hpp) in thf to give cis ‐[(hppH) 2 PtCl 2 ]. The corresponding trans isomer is obtained from the reaction between [(dmso) 2 PtCl 2 ] and hppH. hppH easily replaces another chlorido ligand to give [(hppH) 3 PtCl] + Cl – . [hppH 2 ]Cl is formed as a hygroscopic side‐product in the synthesis of [(hppH) 2 PtCl 2 ] and takes up 1 equiv. of H 2 O to give [hppH 2 ]Cl · H 2 O. We report the crystal structures of cis ‐ and trans ‐[(hppH) 2 PtCl 2 ], [(hppH) 3 PtCl] + Cl – and some salts of the [hppH 2 ] + cation, namely [hppH 2 ] 2 [PtCl 4 ] and the Pt‐free salts [hppH 2 ][BPh 4 ], [hppH 2 ]Cl and [hppH 2 ]Cl · H 2 O, which have an increasing degree of directed intermolecular hydrogen contacts. The crystal structure of [hppH 2 ]Cl · H 2 O features helical chains of Cl – · H 2 O connected via [hppH 2 ] + cations. The effects of hydrogen bonding on the structures of these compounds in the solid state are discussed. Finally, quantum chemical calculations provide further insight into the structures and properties of some of these compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)