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Type studies on competitive polyatomic anion versus acetonitrile coordination in the self-assembly of a series of [Ag 2 -, and PF 6 -; m = 0, 2; n = 0, 2, 4; bip = 1,4-bis(2-isonicotinoyloxyethyl)piperazine) were carried out. Each bip spacer acts as an N 4 tetradentate ligand and is linked to four silver(I) centers through two pyridine and two piperazine moieties, producing a double strand consisting of two 20-membered ring units. The coordinating environment around the silver(I) center is subtly determined by the competition of the polyatomic anions with acetonitrile, that is, by the AgÁÁÁNCCH 3 versus AgÁÁÁX interactions. The coordinating ability of acetonitrile is inversely proportional to the order of the coordination ability of the Hoffmeister series of polyatomic anions, NO 3 -) CF 3 SO 3 -[ ClO 4 -[ BF 4 -) PF 6 -.

The reaction of AgX (X -= NO 3 -, ClO 4 -, or CF 3 SO 3 -) with 1,3-bis(3-pyridyl)tetramethyldisiloxane (L) at room temperature affords 20-membered metallacyclodimers, [Ag(L)] 2 (X) 2 . For the macrocyclodimer, fine competition among argentophilic, electrostatic, and pÁÁÁp interaction exists. The macrocyclodimer is a unique molecular chair that tunes a transannular argentophilic interaction via the bite size of the counteranions. In order to reversibly control the argentophilic interaction, anion exchange has been accomplished. The anion exchangeability depends on the water solubility rather than the electrostatic interaction between silver(I) and anions.

Reaction of [(bpy)Pd](PF6)2 (bpy = 2,2'-bipyridine) with racemic bis(isonicotinoyl)-1,1'-bi-2-naphtholate (L) in acetone, and followed by addition of chloroform and solvent evaporation allows to form amorphous micro-bowl morphology consisting of [(bpy)PdL]2(PF6)4 without any template or additive. In contrast, the reaction and recrystallization in acetone for 1 week produce parallel-piped single crystals consisting of [(bpy)3Pd3(µ3-HPO4)2](PF6)2. The formations of micro-bowl and parallel-piped single crystal morphologies appear to be primarily associated with the kinetic and thermodynamic control, respectively. The formation of micro-bowls may be attributed to eruption of organic solvents. Cosolvent effects and chemical properties on the formation of micro-bowl morphology have been observed.

The reaction of (COD)PdCl 2 (COD = 1,5cyclooctadiene) with (3-Py) 2 SiMe 2 (bis(3-pyridyl)dimethylsilane) in acetone produces single crystals consisting of cyclodimers, [PdCl 2 ((3-Py) 2 SiMe 2 )] 2 , whereas the similar reaction in a mixture of dichloromethane and ethanol yields amorphous submicrospheres consisting of cyclotrimers, [PdCl 2 ((3-Py) 2 SiMe 2 )] 3 . In a boiling chloroform solution, the cyclodimers are completely converted to the cyclotrimers. The structures of both cyclic species are locked at temperatures below 0°C. The cyclotrimer equilibrates to the cyclodimer, the cyclotrimer, and cyclotrimeric mono-DMF adduct, [Pd 3 Cl 5 (DMF)((3-Py) 2 SiMe 2 ) 3 ]Cl in the mole ratio of 6:1:5 in DMF solution at room temperature. The cyclodimer finally reaches the equilibrium in the same condition. ExperimentalPalladium(II) chloride, 1,5-cyclooctadiene (COD), and dichlorodimethylsilane were purchased from Aldrich, and used without further purification. (COD)PdCl 2 [30] and bis(3-pyridyl)dimethylsilane((3-Py) 2 SiMe 2 ) [31] were Electronic supplementary material The online version of this article (

Metallacyclodimers, [Ag(OTf)(L1)]2 and [Ag(L2)]2(OTf)2 (L1 = 1, 3 -dibromo -2,2-bis[ (isonicotinoyloxy)methyl] propane; L2 = 2,5-dimethyl-2,5-bis(isonicotinoyloxy)hexane) were constructed and characterized. The crystal structure of [Ag(OTf)(L1)]2 reveals a 32-membered cyclodimer, whereas that of [Ag(L2)]2(OTf)2 shows a linked 34-membered cyclodimer chain via intercyclic argentophilic (Ag・・・Ag) interactions. [Ag(OTf)(L1)]2 affords "intramolecular n-n interaction cyclodimer" whereas [Ag(L2)]2(OTf)2 produces a racemic mixture of "twisted cyclodimer". Ring-conformation of the cyclodimers was affected via the competition of electrostatic interaction and argentophilic interaction.

The reaction of (tmeda)Pd(ClO 4 ) 2 (tmeda = N,N,N 0 ,N 0 -tetramethylethylenediamine) with L (L = bis (4-(4-pyridylcarboxyl)phenyl)methane) affords the ionic cyclodimeric palladium(II) complex [(tmeda)Pd(L)] 2 (ClO 4 ) 4 . The complex forms an unprecedented microsprout morphology via slow evaporation of acetone in a dilute concentration mixture of acetone and water without any template or additive. In contrast, the palladium(II) complex in a concentrated mixture forms uniform submicrospheres. The formation-process of the micro-sprout morphology has been explained in terms of a stepwise concentration effect. Furthermore, surface modifications and properties of the micro-sprouts via a typical anion exchange or sonication have been studied.