A synthetic access to the first members of expanded corroles 1 and 2 is achieved through formation of two direct pyrrole−pyrrole links by an oxidative coupling reaction. Spectroscopic and structural analysis reveal that 1 and 2 are 22Π aromatic macrocycles despite the nonplanar structure and properties resemble that of isocorroles rather than 22Π sapphyrins. Sapphyrin 1 is an example of the simplest possible expanded porphyrin with 22Π electrons. 1 The existence of sapphyrins was been reported long ago, but their rich and diverse chemistry has been explored only recently after the development of efficient synthetic methodologies allowing their preparation in gram quantities. Removal of one meso carbon from the sapphyrin skeleton results in a new 22Π electron macrocycle with two direct pyrrole-pyrrole links. This structural principle is referred to as "smaragdyrin" 2 in the literature. 2,3 The structural relationship between 1 and 2 is analogous to that between a porphyrin and a corrole; therefore, the chemistry of smaragdyrins is expected to resemble that of corroles. 4 Two previous attempts to syn-(1) For the recent reviews and papers on the expanded porphyrins, see: (a) Jasat, A.; Dolphin, D.

Treatment of lithium tris(trimethylsilyl)silanide, Li(THF)3Si(SiMe3)3, with heavier alkali metal tert-butoxides yielded the alkali metal silanides MSi(SiMe3)3 (M = K, Rb, or Cs) in a simple, high-yielding, one-step procedure. Separation of the two solid reaction products was achieved by addition of crown ether, which also determines the formation of contact or separated ion pairs in the solid state. Here we report the synthesis and structural characterization of the contact ion K(18-crown-6)Si(SiMe3)3, 2, in addition to the separated [K(12-crown-4)2][Si(SiMe3)3], 1, [Rb(15-crown-5)2][Si(SiMe3)3], 3, and [Cs(18-crown-6)2][Si(SiMe3)3], 5. [Rb(18-crown-6)2][Si(SiMe3)3][Rb(18-crown-6)Si(SiMe3)3]2, 4, is a rare example where both contact and separated ions are observed in the solid state. The investigation of synthetic routes toward the target compounds also examined the previously published metalation of Si(SiMe3)4 with potassium tert-butoxide. This route proved to be temperamental:  depending on reaction conditions and solvent systems, either adducts between product and unreacted starting material, namely, [{K(THF)Si(SiMe3)3}{KO t Bu}3], 6, or the target compound KSi(SiMe3)3 was isolated. All compounds were characterized by X-ray crystallography and NMR spectroscopy.

The exploration of synthetic methodologies toward heavy alkaline-earth chalcogenolates resulted in the preparation and structural characterization of a family of calcium thiolates, including [Ca(SC(6)F(5))(2)(py)(4)], 1 (py = pyridine), the separated ion-triple [Ca(18-crown-6)(NH(3))(3))][SMes](2).2THF, 2 (Mes = 2,4,6-tBu(3)C(6)H(2)), and the contact triple [Ca(18-crown-6)(SMes)(2)].THF, 3. Compound 1 was prepared by treating [Ca(N(SiMe(3))(2))(2)](2) with 4 equiv of HSC(6)F(5) under addition of pyridine. The thiolates 2 and 3 were synthesized by treatment of calcium metal dissolved in dry, liquid NH(3) under addition of 2 equiv of HSMes and crown ether or, alternatively, by the reduction of MesSSMes with calcium metal in dry, liquid ammonia. We also report two reaction products isolated during attempted calcium thiolate syntheses: [CaBr(4)(THF)(2)(&mgr;(2)-Li)(2)(THF)(4)], 4, isolated as the product of a salt elimination reaction between CaBr(2) and 2 equiv of [Li(THF)(n)()S-2,4,6-(i)()Pr(3)C(6)H(2)](m)(). [(NH(4))(py)(SC(6)F(5))], 5, was obtained as the sole product in the reaction of metallic calcium with HSC(6)F(5) in liquid ammonia under addition of pyridine. All compounds were characterized by single-crystal X-ray crystallography in addition to IR and NMR spectroscopy.

An easy synthesis of core-modified meso-aryl smaragdyrins containing oxygen and sulfur in addition to pyrrole nitrogens has been achieved through an alpha-alpha coupling involving modified tripyrrane and dipyrromethane. The complexation behavior of these macrocycles toward anions (Cl-, F-, AMP-) and metal cations (Rh(I), Ni(II)) is reported. Specifically, it has been shown that the Rh(I) and Ni(II) ions bind to the smaragdyrin skeleton in its free base form. X-ray structural studies of Rh(I) complex 1 indicate an eta 2-type coordination involving only one imino and one amino nitrogen of the dipyrromethane unit. However, all four bipyrrole nitrogens participate in the coordination with the Ni(II) ion. Furthermore, Ni(II) coordination oxidizes the ligand, and the complex is formulated as the pi-cation radical of nickel(II) smaragdyrin. The anion complexation is followed in both the solid and solution phases. Solution studies reveal that the binding constants of the ions with the protonated form of smaragdyrin vary as F- > AMP- > Cl-. The X-ray structure of the chloride anion complex reveals that the chloride ion is bound above the cavity of the smaragdyrin macrocycle through three N-H...Cl hydrogen bonds. Crystal data with Mo K alpha (lambda = 0.710,73 A) are as follows: 1, C41H27N4O3Rh, a = 11.836(8) A, b = 12.495(9) A, c = 12.670(2) A, alpha = 69.09(6) degrees, beta = 78.78(6) degrees, gamma = 77.02(5) degrees, V = 1692.1(17) A3, Z = 2, triclinic, space group P-1, R1 (all data) = 0.0471; 4.HCl, C41H29N4O1Cl, a = 11.878(2) A, b = 17.379(4) A, c = 16.015(3) A, beta = 109.546(10) degrees, V = 3115.47(11) A3, Z = 4, monoclinic, space group P2(1)/c, R1(all data) = 0.0850.

An unprecedented ligand bending mode is displayed by the acetylide ligands in the first structurally characterized σ-bound organometallic strontium and barium complexes [M([18]crown-6)(CCSiPh ) ] (M=Sr, Ba). Furthermore, the observed decrease of the angle at the sp-hybridized C atom on descending Group 2 (see structures depicted) affords new information that will lead to a better understanding of the bonding in alkaline earth metal compounds.

Recent studies have defined a data-collection protocol and a metric that provide a robust measure of global radiation damage to protein crystals. Using this protocol and metric, 19 small-molecule compounds (introduced either by cocrystallization or soaking) were evaluated for their ability to protect lysozyme crystals from radiation damage. The compounds were selected based upon their ability to interact with radiolytic products (e.g. hydrated electrons, hydrogen, hydroxyl and perhydroxyl radicals) and/or their efficacy in protecting biological molecules from radiation damage in dilute aqueous solutions. At room temperature, 12 compounds had no effect and six had a sensitizing effect on global damage. Only one compound, sodium nitrate, appeared to extend crystal lifetimes, but not in all proteins and only by a factor of two or less. No compound provided protection at T=100 K. Scavengers are ineffective in protecting protein crystals from global damage because a large fraction of primary X-ray-induced excitations are generated in and/or directly attack the protein and because the ratio of scavenger molecules to protein molecules is too small to provide appreciable competitive protection. The same reactivity that makes some scavengers effective radioprotectors in protein solutions may explain their sensitizing effect in the protein-dense environment of a crystal. A more productive focus for future efforts may be to identify and eliminate sensitizing compounds from crystallization solutions.

Novel alkaline earth metal aryl-substituted silylamides were prepared using alkane (Mg) and salt elimination reactions (Mg, Ca, Sr, and Ba). The salt elimination regime involved the treatment of the alkaline earth metal iodides with 2 equiv of the respective potassium amide KNDiip(SiMe(3)), (Diip = 2,6-i-Pr(2)C(6)H(3)). The organomagnesium source for the alkane elimination was ((n)()Bu/(s)()Bu)(2)Mg. All compounds were characterized using (1)H, (13)C NMR, and IR spectroscopy, in addition to X-ray crystallography (except Mg[NDiip(SiMe(3))](2)THF(2)). Crystal data with Mo Kalpha (lambda = 0.710 73 A) are as follows: Mg[NDiip(SiMe(3))](2), 1, a = 9.4687(6) A, b = 9.6818(6) A, c = 17.9296(1) A, alpha = 96.487(1) degrees, beta = 94.537(1) degrees, gamma = 89.222(1) degrees, V = 1608.8(2) A(3), Z = 2 (two independent molecules), triclinic, space group P(-)1, R1 (all data) = 0.0508; (n)()BuMg[NDiip(SiMe(3))]THF(2), 2, a = 9.5413(1) A, b = 16.493(2) A, c = 9.8218(1) A, beta = 108.149(2) degrees, V = 1468.7(4) A(3), Z = 2, monoclinic, space group P2(1), R1(all data) = 0.1232; Ca[NDiip(SiMe(3))](2)THF(2), 4, a = 9.7074(1) A, b = 20.9466(4) A, c = 21.6242(3) A, alpha = 73.573(1) degrees, beta = 78.632(1) degrees, gamma = 89.621(1) degrees, V = 4129.1(1) A(3), Z = 4 (two independent molecules), triclinic, space group P(-)1, R1 (all data) = 0.0902; Sr[NDiip(SiMe(3))](2)THF(2), 5, a = 20.5874(5) A, b = 9.8785(2) A, c = 20.8522(5) A, beta = 102.035(2) degrees, V = 4147.6(2) A(3), Z = 4 (two independent molecules), monoclinic, space group P2/n, R1 (all data) = 0.0756; Ba[NDiip(SiMe(3))](2)THF(2), 6, a = 20.5476(2) A, b = 10.0353(2) A, c = 20.9020(4) A, beta = 101.657(1) degrees, V = 4221.0(1) A(3), Z = 4 (two independent molecules), monoclinic, space group P2/n, R1 (all data) = 0.0573.

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