Hydrogen-bond rigidified BODIPY dyes.

Boron difluoride adducts of diamidodipyrromethenes have been synthesized and characterized. The compounds represent a new group of the BODIPY family of fluorescent dyes. X-ray crystallography and solution (19)F NMR experiments show that a persistent hydrogen bond is formed between the boron-bound fluoride groups and the peripheral amide substituents. The modular synthesis of these compounds and their robust photophysical properties suggest that they may be useful compounds for materials and biological photochemical applications.

Diamidodipyrrins: versatile bipyrrolic ligands with multiple metal binding modes.

A straightforward, facile synthesis of diamidodipyrromethenes (diamidodipyrrins, DADP (R,R')) is presented. These tetradentate ligands readily form complexes with metal ions such as Ni (2+) and Cu (2+) and can adopt different binding modes with these metals. One version of the ligand (DADP (Ph, iPr )) has been structurally characterized in its "free base" form, as a HBr salt, and as the Ni (2+) and Cu (2+) complexes. A symmetric NNOO donor set is found for the Cu (2+) complex in the solid state, involving two carbonyl oxygen atoms and two dipyrrin nitrogen atoms, and this coordination mode has been confirmed in solution by electron paramagnetic resonance. An asymmetric NNNO binding mode found for the Ni (2+) complex in the solid state persists in solution as revealed by (1)H NMR. The HBr salt form of the ligand shows an intriguing hydrogen-bonded head-to-head dimer arrangement. Experiments show that Cu (2+), but not Ni (2+), can mediate the rapid oxidation of the diamidodipyrromethane precursors to the diamidodipyrromethene ligands in the presence of dioxygen. The work here shows that diamidodipyrrins are a versatile new class of ligands in the area of nonporphyrinic pyrrole-based compounds that merit further investigation.

Rare examples of transition-metal-main-group metal heterometallic metal-organic frameworks from gallium and indium dipyrrinato complexes and silver salts: synthesis and framework variability.

New main-group metal dipyrrinato complexes [M(4-pyrdpm)3], where M = Ga3+ or In3+ and 4-pyrdpm is the anion of 5-(4-pyridyl)dipyrrin (4-pyrdpmH), have been synthesized and incorporated into metal-organic frameworks (MOFs) by reacting the dipyrrinato complexes with silver(I) salts. MOFs formed with AgOTf (OTf = O3SCF3) and AgSbF6 gave frameworks with three-dimensional (10,3) and two-dimensional (6,3) topologies, respectively. In contrast, AgPF6 produced both (10,3) and (6,3) network topologies, suggesting that the PF6 anion has little preference for templating (10,3) versus (6,3) frameworks within this system. These findings update an earlier MOF study that examined the role of these anions in templating related heterometallic MOFs which used [Fe(4-pyrdpm)3] and [Co(4-pyrdpm)3] metalloligands. All of the dipyrrin compounds reported here have been characterized by single-crystal X-ray crystallography, including the first crystallographically characterized example of a 1,2,3-unsubstituted free-base dipyrrin, 4-pyrdpmH.

Adventures in crystallization. Crystalline salts containing one, two, or even three chemically distinct cations obtained from solutions of [(cyclohexyl isocyanide)(4)Rh(I)]+.

By judicious selection of crystallization conditions, it has been possible to obtain the salts of a common building block, [(RNC)4Rh(I)]+, in single-crystal form suitable for X-ray diffraction. Salts that contain a single type of cation include deep green [(C6H11NC)12Rh(I)3](SbF6)3, deep green [(C6H11NC)12Rh(I)3](AsF6)3, and straw yellow [(C6H11NC)8Rh(II)2Cl2](BF4)2 (in addition to the previously isolated trimeric deep green [(i-PrNC)12RhI3]Cl3 x 4.5 H2O, monomeric, [(C6H11NC)4 Rh(I)](BPh4), and [(i-PrNC)4Rh(I)](BPh4) (both yellow), and red, dimeric [(C6H11NC)8Rh(I)2]Cl2 x 0.5C6H6 x 2H2O). Ordered crystals of [(C6H11NC)12Rh(I)3](SbF6)3 contain linear Rh3 units, while those of [(C6H11NC)12Rh(I)3](AsF6)3 show disorder which is consistent with the presence of linear or bent Rh3 units. The formation of green [(C6H11NC)12Rh(V/III)3Cl2][(C6H11NC)12Rh(I)3]Cl6, and brown [(C6H11NC)12Rh(V/III)3Cl2][(C6H11NC)8Rh(I)2][(C6H11NC)4RhI]Cl6 x 16H2O x 3C6H6 along with unidentified red-brown cubes from an air-exposed solution of [(C6H11NC)4Rh(I)]Cl is reported. As their formulas indicate, green [(C6H11NC)12Rh(V/III)3Cl2][(C6H11NC)12Rh(I)3]Cl6, and brown [(C6H11NC)12Rh(V/III)3Cl2][(C6H11NC)8Rh(I)2][(C6H11NC)8Rh(I)]Cl6 x 16H2O x 3C6H6 contain two or three chemically distinct cations, respectively, but again are built from a common precursor, [(C6H11NC)4Rh(I)]+.

Preparation and characterization of asymmetric alpha-alkoxy dipyrrin ligands and their metal complexes.

Asymmetric alpha-substituted dipyrrins have been synthesized and characterized. The compounds were formed by a metal mediated reaction involving a single alkoxy group substituted into the alpha-position of an alpha,beta-unsubstituted dipyrrin. An alpha-methoxy dipyrrin, 5-(4-cyanophenyl)-1-methoxydipyrrin (alpha-OMe-4-cydpm), was prepared from 5-(4-cyanophenyl)-4,6-dipyrromethane. Methoxy, ethoxy, and propoxy derivatives (alpha-OMe-4-mecdpm, alpha-OEt-4-mecdpm, alpha-OPr-4-mecdpm) of 5-(4-methoxycarbonylphenyl)-4,6-dipyrromethane have also been prepared. A homoleptic, bis(1-methoxy)dipyrrinato zinc(II) complex, [Zn(alpha-OMe-4-mecdpm)(2)], has been synthesized, as has a heteroleptic cobalt(III) complex with one alpha-OMe-4-cydpm ligand and two unsubstituted 5-(4-cyanophenyl)dipyrrin (4-cydpm) ligands ([Co(alpha-OMe-4-cydpm)(4-cydpm)(2)]). The rotational barrier of the meso-aryl substituent of [Zn(alpha-OMe-4-mecdpm)(2)] was found to be 17.3 kcal mol(-1) by variable-temperature NMR spectroscopy. The compounds alpha-OMe-4-cydpm and [Zn(alpha-OMe-4-mecdpm)(2)] have also been characterized by X-ray diffraction. The formation of the new dipyrrin derivatives is shown to be general and can be performed on dipyrrins with various meso-aryl substitutents, with a variety of alcohols, and can be promoted by several metal salts.

Enantiopure vs. racemic metalloligands: impact on metal-organic framework structure and synthesis.

Carboxylate-decorated tris(dipyrrinato) cobalt(III) complexes have been used to construct 2-D and 3-D metal-organic frameworks with infinite and trinuclear zinc secondary-building units.

Luminescent dipyrrinato complexes of trivalent group 13 metal ions.

Although free dipyrrins (dipyrromethenes) do not strongly luminesce, certain dipyrrinato complexes of BF2 and zinc(II) are known to be intensely luminescent species. Two new dipyrrinato fluorophores, based on complexes with gallium(III) and indium(III), are described. Using a previously described meso-mesityl-substituted dipyrrin, namely 5-mesityldipyrrin (mesdpm), the complexes [Ga(mesdpm)3] and [In(mesdpm)3] were prepared and structurally characterized. The complexes display the expected octahedral geometry about the metal ions. In some solvents, such as hexanes, the complexes emit green light upon excitation with UV light at room temperature, with quantum yields of 2.4% ([Ga(mesdpm)3]) and 7.4% ([In(mesdpm)3]) and lifetimes in the low nanosecond range. Observations are consistent with assignment to ligand-localized transitions, and this interpretation is further confirmed by density functional calculations described herein. The new complexes are important additions to the widely used family of dipyrrin-based fluorescent species and show that dipyrrinato complexes containing metals other than BF2 and zinc(II) may be useful fluorophores.

Topological control in heterometallic metal-organic frameworks by anion templating and metalloligand design.

Several new heterometallic metal-organic frameworks (MOFs) based on tris(dipyrrinato) metalloligands and Ag+ salts are reported. MOFs were prepared systematically to examine the effects of the core metal ion, counteranion, and ligand structure on the topology of the resultant network. The effect of the metal ion (Fe3+ vs Co3+) on MOF structure was generally found to be negligible, thereby permitting the facile synthesis of trimetallic Fe/Co/Ag networks. The choice of anion (e.g., silver salt) was found to have a pronounced effect on the MOF topology. Networks prepared with salts of AgO3SCF3 and AgBF4 reliably formed three-dimensional (10,3) nets, whereas use of AgPF6 and AgSbF6 produced two-dimensional (6,3) honeycomb nets. The topology generated upon formation of the MOF was found to be robust in certain cases, as demonstrated by anion-exchange experiments. Anion exchange was confirmed by X-ray crystallography in a rare set of apparent single-crystal-to-single-crystal transformations. The data presented here strongly suggest that the coordinative ability of the anion does not play a significant role in the observed templating effect. Finally, changes in the length of the tris(dipyrrinato) metalloligand were found to override the anion templating effect, resulting exclusively in two-dimensional (6,3) nets. These studies provide a basis for the rational design of MOF topologies by choice of ligand structure and anion templating effects. Furthermore, the results demonstrate the ability of carefully designed metalloligands to generate MOFs of structure strikingly similar to that of their organic counterparts.

Chloro and hydroxo forms of a boron(III) subtriazaporphyrin macrocycle.

cis-3,4-Dicyano-3-hexene undergoes cyclotrimerization with BCl3 to form the new subtriazaporphyrin chloro[hexaethylsubtriazaporphyrinato]boron(III). The hydroxo derivative of this macrocycle has also been made, and the X-ray crystal structure of the hydroxy form was determined. Electronic absorption and magnetic circular dichroism spectra of the hydroxo monomer species were interpreted using time-dependent density functional theory calculations.

Variation in crystallization conditions allows the isolation of trimeric as well as dimeric and monomeric forms of [(alkyl isocyanide)4RhI]+.

Trimeric green [(i-PrNC)12Rh(I)3]Cl3.4.5H2O, monomeric [(C6H11NC)4Rh(I)](BPh4) and [(i-PrNC)4Rh(I)](BPh4) (both yellow), and red, dimeric [(C6H11NC)8Rh(I)2]Cl2.0.5C6H6.2H2O have been crystallized.

Metal-metal interactions in thallium(I)/platinum(II) compounds involving a chelating dicarbene and various auxiliary ligands.

Reaction of Tl(I)NO(3) and (C(4)H(10)N(4))Pt(II)(mnt) or (C(4)H(10)N(4))Pt(II)(dmg-H) [mnt = maleonitriledithiolate, dmg-H = dimethylglyoximate dianion] in dilute, aqueous KOH yielded adducts of Tl(I) and the conjugate bases of the platinum(II) compounds. The compound Tl(I)[(C(4)H(9)N(4))Pt(II)(dmg-H)].5H(2)O forms as dimers with close Tl(I)...Pt(II) separations of 3.0843(5) A, while Tl(I)[(C(4)H(9)N(4))Pt(II)(mnt)] has much longer Tl(I)...Pt(II) separations of 3.4400(2) A and forms loosely associated, helical coordination polymers. The new compounds are compared with the red and yellow polymorphs of Tl(I)[(C(4)H(9)N(4))Pt(II)(CN)(2)], and the influences of crystal packing forces, Coulombic interactions, and hydrogen bonding on supramolecular structures and Tl(I)...Pt(II) separations are discussed.

Metal-metal interactions in platinum(II)/gold(I) or platinum(II)/silver(I) salts containing planar cations and linear anions.

The salts [Pt{C(NHMe)(2)}(4)][Au(CN)(2)](2), [Pt{C(NHMe)(2)}(4)][Ag(2)(CN)(3)][Ag(CN)(2)], [Pt(en)(2)][Au(CN)(2)](2), [Pt(en)(2)][Ag(CN)(2)](2), and [Pt(bipy)(2)][Au(CN)(2)](2) have been prepared by mixing solutions of salts containing the appropriate cation with solutions of K[Au(CN)(2)] or K[Ag(CN)(2)]. Because the platinum atom in the cation is sterically protected, the structures of [Pt{C(NHMe)(2)}(4)][Au(CN)(2)](2) and [Pt{C(NHMe)(2)}(4)][Ag(2)(CN)(3)][Ag(CN)(2)] reveal no close metal-metal interactions. Colorless crystals of [Pt(en)(2)][Au(CN)(2)](2) and [Pt(en)(2)][Ag(CN)(2)](2) are isostructural and involve extended chains of alternating cations and anions that run parallel to the crystallographic a axis, along with isolated anions. In the chains, the metal-metal separations are relatively short: Pt...Au, 3.1799(3) Angstroms; Pt...Ag, 3.1949(2) Angstroms. In [Pt(bipy)(2)][Au(CN)(2)](2), each cation has axial interactions with the anions through close Pt...Au contacts [3.1735(6) Angstroms]. In addition, the anions are weakly linked through Au...Au contacts of 3.5978(9) Angstroms. Unlike the previously reported Pt/Au complex [Pt(NH(3))(4)][Au(CN)(2)](2).1.5H(2)O, which is luminescent, none of the salts reported here luminesce.

Polymorphs with varying platinum(II)-thallium(I) interactions.

TlI[(C4H9N4)PtII(CN)2] forms a red, crystalline polymorph in which the ions are arranged to form an extended ...Pt...Tl...Pt...Tl... chain (Pt...Tl distance, 3.0978(2) A; Pt-Tl-Pt and Tl-Pt-Tl angles, (171.37(2) degrees ) and a yellow polymorph in which dimers are connected by pairs of Pt...Tl interactions with a Pt...Tl distance of 3.0256(5) A.

Effects of Pt...Pt bonding, anions, solvate molecules, and hydrogen bonding on the self-association of Chugaev's cation, a platinum complex with a chelating carbene ligand.

Five salts, [(C(4)H(9)N(4))Pt(II)(CNCH(3))(2)](BPh(4)).CH(3)OH, [(C(4)H(9)N(4))Pt(II)(CNCH(3))(2)](PF(6)).CH(2)Cl(2), [(C(4)H(9)N(4))Pt(II)(CNCH(3))(2)]Cl.4H(2)O, [(C(4)H(9)N(4))Pt(II)(CNCH(3))(2)]Br.3.5H(2)O, and [(C(4)H(9)N(4))Pt(II)(CNCH(3))(2)]Cl.0.1H(2)O, have been crystallized and examined by single crystal X-ray diffraction. While the internal structure of the cation is similar in all salts, the interactions between cations vary in the different salts. Yellow [(C(4)H(9)N(4))Pt(II)(CNCH(3))(2)](BPh(4)).CH(3)OH and red [(C(4)H(9)N(4))Pt(II)(CNCH(3))(2)](PF(6)) form face-to-face dimers with Pt...Pt separations of 3.6617(6) and 3.340(2) A, respectively. In the latter, hydrogen bonding of the chelating ligand to adjacent anions facilitates the close approach of pairs of cations. The salts [(C(4)H(9)N(4))Pt(II)(CNCH(3))(2)]Cl.4H(2)O, [(C(4)H(9)N(4))Pt(II)(CNCH(3))(2)]Br.3.5H(2)O, and [(C(4)H(9)N(4))Pt(II)(CNCH(3))(2)]Cl.0.1H(2)O form columnar structures with Pt...Pt separations that range from 3.2514(5) to 3.5643(6) A. The water molecules and anions surround these columns and form bridges between neighboring columns. The electronic spectra of aqueous solutions of [(C(4)H(9)N(4))Pt(II)(CNCH(3))(2)]Cl.4H(2)O show spectral changes upon increasing concentrations of the platinum complex that are indicative of the formation of a dimer in solution with an equilibrium constant for dimerization of 23(1).