Synthesis of the 2,2 -dipyridylamine derivatives di-2-pyridylaminomethylbenzene 1, 1,2-bis(di-2-pyridylaminomethyl)benzene 2, 1,3-bis(di-2-pyridylaminomethyl)benzene 3, 2,6-bis(di-2-pyridylaminomethyl)pyridine 4, 1,4-bis(di-2-pyridylaminomethyl)benzene 5, and 1,3,5-tris(di-2-pyridylaminomethyl)benzene 6 are reported together with the single-crystal X-ray structures of 2, 3, and 5. Reaction of individual salts of the type AgX (where X = NO 3 − , PF 6 − , ClO 4 − , or BF 4 − ) with the above

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... ds has led to the isolation of thirteen Ag(I) complexes, nine of which have also been characterised by X-ray diffraction. In part, the inherent flexibility of the respective ligands has resulted in the adoption of a range of coordination arrangements. A series of liquid-liquid (H 2 O/CHCl 3 ) extraction experiments of Ag(I) with varying concentrations of 1-6 in the organic phase have been undertaken, with the counter ion in the aqueous phase being respectively picrate, perchlorate and nitrate. In general, extraction efficiencies for a given ionophore followed the Hofmeister order of picrate > perchlorate > nitrate; in each case the tris-dpa derivative 6 acting as the most efficient extractant of the six systems investigated. Competitive seven-metal bulk membrane transport experiments (H 2 O/CHCl 3 /H 2 O) employing the above ligands as the ionophore in the organic phase and equimolar concentrations of Co(II), Ni(II), Zn(II), Cu(II), Cd(II), Pb(II) and Ag(I) in the aqueous source phase were also undertaken, with transport occurring against a pH gradient. Under the conditions employed 1 and 5 yielded negligible transport of any of the metals present in the source phase while sole transport selectivity for Ag(I) was observed for 2-4 and 6. † The HTML version of this article has been enhanced with colour images. ‡ Electronic supplementary information (ESI) available: Additional crystallographic parameters and ORTEP diagrams. See Crystals employed for the X-ray determinations were obtained directly from the respective reaction solutions and were used without further drying. Structures of 2, {[Ag(3)(CH 3 CN)](ClO 4 )· CH 3 CN} n and [Ag 2 (3) 2 (ClO 4 ) 2 ]·2H 2 O were collected on a Nonius Kappa CCD with x and w scans to approximately 56 • 2h at 198(2) K. Data collections were undertaken with COLLECT, 21 cell refinement with Dirax/lsq, 22 data reduction with EvalCCD 23 and structure solution with SHELXS-97. 24 Structures of 5, [Ag 2 (2) 2 (NO 3 ) 2 ], [Ag 2 (2) 2 ](BF 4 ) 2 , {[Ag 2 (2) 2 ](PF 6 ) 2 } 3 ·2CH 2 Cl 2 · 2CH 3 OH, [Ag(3)(NO 3 )], {[Ag(3)(CH 3 OH)](PF 6 )} n and [Ag 3 (5) 2 -(H 2 O) 0.5 ](PF 6 ) 3 ·1.5H 2 O, were collected at 168(2) K using a Bruker SMART 1000 diffractometer with a CCD area detector with x and w scans to approximately 53 • 2h. Data integration and reduction were undertaken with SAINT and XPREP. 25 The structures were solved by direct methods using SHELXS-97. 24 Structures of 3 and [Ag (6) NO 3 ] were collected at 150(2) K with x scans to approximately 56 • 2h using a Bruker SMART 1000 diffractometer. Data integration and reduction were undertaken with SAINT and XPREP 25 and subsequent computations were carried out using the WinGX-32 graphical user interface. 26 These structures were solved by direct methods using SIR97. 27 All three diffractometers employed graphite-monochromated Mo-Ka radiation generated from a sealed tube (0.71073 Å ). Multi-scan empirical absorption corrections were applied to all data sets, where appropriate, using the program SADABS. 28 All structures were refined and extended with In general, ordered non-hydrogen atoms with occupancies greater than or equal to 0.5 were refined anisotropically. Partial occupancy carbon, nitrogen and oxygen atoms were refined isotropically. Carbon-bound hydrogen atoms were included in idealised positions and refined using a riding model. Oxygen-bound hydrogen atoms that were structurally 4786 | Dalton Trans., 2006, 4783-4794 This journal is