The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Reaction of 3-(2-pyrazinyl)pyrazole with KBH 4 in a 21:1 ratio afforded the new ligand bisdihydroborate [L] - a bis(pyrazolyl)borate in which each pyrazolyl ring is functionalised with a pyrazin-2-yl group at the C 3 position[L] - is therefore a potentially chelating tetradentate ligand with two externally-directed N atoms (the pyrazinyl N 4 atoms) which are available for additional metal-ion bindingleading to eg coordination polymers The crystal structure of [TlL] shows it to be a simple mononuclear complex with the Tl(I) ion coordinated in the N 4 binding pocket of the ligandand the externally-directed N atoms involved only in intermolecular N H-C hydrogen-bonding interactions The two Tl-N bonds to the pyrazolyl N 2 atoms (average length 270 9) are much shorter than the bonds to the pyrazinyl N 1 atoms (average length 305 9) also there is an obvious gap in the apical position of the metal-ion coordination sphere characteristic of a stereochemically active lone pair The crystal structure of [PbL 2 ] Et 2 O shows that the Pb(II) centre is nine-coordinate with two tetradentate chelating ligands and the ninth donor being a pyrazinyl N 4 atom from an adjacent complex unit The molecules therefore form infinite one-dimensional chains in the crystal via bridging pyrazinyl groups The coordination geometry about the Pb(II) ions is approximately capped square antiprismatic with no obvious gap in the coordination sphere suggesting that the lone pair is stereochemically inactive.