Platinum(II) bi- and terpyridyl chloro complexes, Pt(dcbpy)Cl2 and [Pt(ttpy)Cl]+, where dcbpy = 4,4'-dicarboxyl-2,2'-bipyridine and ttpy = 4-tolyl-2,2':6',2''-terpyridine, are used to investigate the nature of the active catalyst for the photocatalytic production of hydrogen from water. In a Pt(II) chloro system that contains a sacrificial electron donor, either MeOH or triethanolamine (TEOA), and titanium dioxide (TiO2) as an electron relay, sizable amounts of H2 can be observed upon UV bandgap irradiation. The quantity of H2 can be significantly reduced in the presence of mercury under the same conditions. Using a known sensitizer, [Pt(ttpy)(phenylacetylide)]+ (1), combined with a Pt(II) chloro complex in a similar system, there is a substantial induction period until the evolution of H2, under visible light (lambda > 410 nm) irradiation. It is suggested that the Pt(II) chloro complexes are simply acting as precursors to Pt colloids that function as the H2 generating catalyst

[Structure: see text]. The synthesis and characterization of a series of organochalcogen (Se, Te) compounds derived from benzyl alcohol 13 are described. The synthesis of the key precursor dichalcogenides 15, 22, and 29 was achieved by the ortho-lithiation route. Selenide 18 was obtained by the reaction of the dilithiated derivative 14 with Se(dtc)2. Oxidation of 15 and 22 with H2O2 afforded the corresponding cyclic ester derivatives 17 and 24, respectively. Oxidation of selenide 18 with H2O2 affords the spirocyclic compound 19. The presence of intramolecular interactions in dichalcogenides 15 and 22 has been proven by single-crystal X-ray studies. The cyclic compounds 17 and 19 have also been characterized by single-crystal X-ray studies. GP(X)-like antioxidant activity of selenium compounds has been evaluated by the coupled bioassay method. Density functional theory calculations at the mPW1PW91 level on ditelluride 22 have identified a fairly strong nonbonding interaction between the hydroxy oxygen and tellurium atom. The second-order perturbation energy obtained through NBO analysis conveys the involvement of n(O) --> sigma(Te-Te) orbital overlap in nonbonding interaction. Post wave function analysis with the Atoms in Molecules (AIM) method identified distinct bond critical point in 15 and 22 and also indicated that the nonbonding interaction is predominantly covalent. Comparison between diselenide 15 and ditelluride 22 using the extent of orbital interaction as well as the value of electron density at the bond critical points unequivocally established that a ditelluride could be a better acceptor in nonbonding interaction, when the hydroxy group acts as the donor.

22-Membered mercuraazametallamacrocycles 6, 7, and 12 have been synthesized by dipodal condensation (2 þ 2) of bis(o-formylphenyl)mercury ( 11) and 1,2-disubstituted amines. Reduction of macrocycle 6 with sodium borohydride afforded novel 11-membered mercuraazametallamacrocycle 13. Macrocycle 6, when treated with [Cu(CH 3 CN) 4 ]ClO 4 and Cu(OCOCH 3 ) 2 /NH 4 PF 6 , formed orange-colored Cu I complexes 14 ([6 3 Cu]ClO 4 ) and 15 ([6 3 Cu]PF 6 ), respectively, whereas redcolored complex 16 ([12 3 Cu]ClO 4 ) was obtained from the reaction of 12 with [Cu(CH 3 CN) 4 ]ClO 4 . Similarly, complexes 17 ([6 3 Ag]ClO 4 ) and 18 ([6 3 Ag]PF 6 ) were synthesized by the reaction of 6 with the corresponding silver salts. The reaction of 6 with Hg(OCOCH 3 ) 2 /NH 4 PF 6 led to the formation of hydroxo-bridged complex 19. The reaction of macrocycle 7 with Pd(C 6 H 5 CN) 2 Cl 2 gave access to novel complex 9a. The macrocycles and the complexes have been characterized by elemental analysis, NMR ( 1 H, 13 C, 199 Hg), fluorescence spectroscopy, and cyclic voltammetry. The molecular structures of organomercury precursors Hg{1-C 6 H 4 -2-(CH 2 OH)} 2 (10) and Hg{1-C 6 H 4 -2-(CHO)} 2 (11) and macrocycles 6, 7, and 12 show almost linear geometry around mercury; however, 13 shows a bent structure, i.e., significant deviation of the C-Hg-C angle from linearity. 22-Membered mercuraazametallamacrocycles 6, 7, and 12 are stabilized by secondary Hg 3 3 3 N intramolecular interaction and have an "hour-glass"-like conformation. The molecular structures of 14, 17, and 9a showed metallophilic interactions. The metal ions (Cu I and Ag I ) are coordinated not only to the four nitrogens but also to two mercury atoms, forming a distorted octahedral geometry around the metal ions.

Abstract. Mr= 179.21, monoclinic, P21/c, a= 13.25 (2), b= 9.65 (1), c--7.81 (1) A, fl= 104.9 (5) °, V= 965 (2)/~3, Z = 4, Dm-~ 1.240 (4), Ox= 1.234 (3) Mg m -3, Cu K~t, 2 = 1.5418 A,, /1 = 0.66 mm -~, F(000) = 384, T = 300 K, R = 0.088 for 1459 observed reflections. The planes of the side groups O(7)C(8)C(9) and N(10)C(11)C(12)O(13) are tilted with respect to the plane of the benzene ring by 9 (1) and 29 (1) °, respectively. The nitrogen and oxygen atoms of the acetamido group from two symmetryrelated molecules are hydrogen bonded. The crystal structure is stabilized by hydrogen bonds and van der Waals forces.

The [2+2] cyclocondensation of bis(o-formylphenyl)chalcogenides (9, 10) with trans-1,2-diaminocyclohexane affords novel macrocyclic ligands 11 and 12 in very good yields. Crystals of 11 are triclinic, space group P1 with a = 11.4037(11), b = 11.8184(12), c = 14.6835(14) Å, Z = 4 and those of 12 are triclinic, space group P1 with a = 11.2692(9), b = 12.8612(11), c = 15.2439(12) Å and Z = 2. Reduction of 11 with sodium borohydride affords macrocycle 13. The coordination chemistry of 11 has been studied with the "hard" metal ions Ni II and Co II . Reaction of NiCl 2 ·6H 2 O with one molar equivalent of 11 in refluxing methanol followed by addition of NH 4 PF 6 affords Ni II complex 14. The assignment of an octahedral geometry to 14 follows from its paramagnetism (µ eff = 2.50 µ B ) and UV/Vis spectrum and was further con-

Macrocyclic multidentate Lewis acids have attracted considerable interest as electrophilic hosts in supramolecular chemistry. The electrophilic hosts generally use tin, [1] silicon, [2] boron, [3] germanium, [4] and mercury [5][6][7][8] atoms as binding sites for neutral and anionic electron-rich guests. Polydentate organomercurials are the most investigated series of all the multidentate Lewis acids and have applications as catalysts [9] and sensors.[10] These organomercurials include trimeric perfluoro-o-phenylenemercury (1), [6a] [9]mercuraborand-3 (2), [12]mercuracarborand-4 (3), [7] the 24-membered macrocyclic perfluoroglutarate 4, [8b] and the cyclic pentameric [(CF 3 ) 2 CHg] 5 macrocycle 5.[6b] Some of these compounds exhibit short intermolecular Hg···Hg metallophilic interactions in the solid state, and these metallophilic interactions are often associated with unusual luminescent properties. [5b,c, 11] Whereas the interaction of metallamacrocycles with electron-rich species has been studied extensively, their coordination through short metal-metal interactions with cations is still largely unexplored. However, the work of Catalano et al. on mixed-metal metallocryptands [12] formed by self-assembly is a notable exception. Severin and co-workers also reported a similar metallamacrocycle, an organometallic [12]metallacrown-3 species, that was obtained by self-assembly.[13]Herein, we present a metallamacrocycle that contains both a Lewis acidic mercury center and basic nitrogen atoms in a preorganised macrocycle and a cation complex of a mercuramacrocycle that exhibits metallophilic interactions between the coordinated Cu I and Hg II centers. The white and air-stable, novel 22-membered metallamacrocycle 9 was prepared by [2+2] cycloaddition of 8 [14] with ethylenediamine in high yield without recourse to a template. The precursor 8 was synthesized from benzyl alcohol by lithitation.Ortho-lithiation of benzyl alcohol, followed by treatment with mercuric chloride, afforded compound 7, which was oxidized with pyridinium chlorochromate (PCC) to give 8 in good yield (Scheme 1). The Hg···O intramolecular interaction in 8 presumably plays a role in macrocyclization. To synthesize the Cu I complex, ligand 9 was treated with one equivalent of [Cu(CH 3 CN) 4 ]ClO 4 in methanol to afford an orange-yellow-colored complex 10. In an attempt to prepare a Cu II complex, 9 was treated with Cu(OCOCH 3 ) 2 , followed by an excess of ammonium hexafluorophosphate. An orangeyellow-colored Cu I complex 11 was produced unexpectedly with PF 6 À as the counter ion (Scheme 1). Both complexes were characterized by IR, 1 H NMR, and 13 C NMR spectroscopic analysis, as well as MS(ESI) and elemental analysis. The reduction of the Cu II ion without a reducing agent is not Scheme 1. Synthetic route to the 22-membered mercuramacrocycle 9 and its Cu I complexes: a) nBuLi (2 equiv), À78 8C, THF, HgCl 2 ; b) PCC, CH 2 Cl 2 ; c) H 2 NCH 2 CH 2 NH 2 ,

No abstract

We report selenazamacrocycle hosts that are the first system to change guest binding affinity from cation to anion depending upon macrocycle oxidation/reduction. Selective cation (Fe2+) or anion (BF4-) binding occurs with both ions present and under identical reaction conditions. We also report the first macrocyclic complex with a Fe-Se bond.