Hexafluorosilicate and tetrafluoroborate coordination to lead(II) di- and tri-imine complexes – Unusual fluoroanion coordination modes

Lead(II) tetrafluoroborate and hexafluorosilicate complexes with 2,20-bipyridyl, 1,10-phenathroline and 2,20:60 ,200-terpyridyl have been prepared from the ligand and lead salt in aqueous/MeCN. Crystal structures are reported for [Pb(bipy)2(SiF6)], [Pb(phen)2(SiF6)] and [Pb(bipy)2(BF4)2] which are dinuclear with each lead coordinated ‘‘cis’’ to the two diimines and with the bridging fluoroanions completing eight or nine-coordination. [Pb(phen)2(BF4)2] is eight-coordinate and mononuclear with ‘‘cis’’ diimines and two j-BF4 groups. [Pb(phen)2(H2O)2(SiF6)] is also mononuclear with a j-SiF6 group and two coordinated water molecules. Reaction of Pb(BF4)2 with 2,20:60,200-terpyridyl gave only [Pb(terpy)3][BF4]2, but Pb(SiF6) produced [Pb(terpy)(H2O)(SiF6)], which is a chain polymer with bridging SiF6 groups and significant pstacking of the imine rings. The work has identified a number of coordination modes of the SiF6 anion, which has been little used in coordination chemistry but proves to be versatile and also stable (to decomposition/hydrolysis). 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/).