Charles E. Strouse

Crystalline complexes, coordination polymers and aggregation modes of tetra(4-pyridyl)porphyrin

Aggregation patterns of tetra(4-pyridyl)porphyrin and of its zinc(II) complex in seven new solid materials have been investigated by X-ray diffraction. The metalloporphyrin compound forms two types of coordination polymers through ligation of the porphyrin periphery on one molecule to the metal center of an adjacent porphyrin. These include one-dimensional chains with a zigzag conformation, as well as three-dimensional, extensively interlinked, polymeric structures. The non-metallated compound reveals a characteristic layered arrangement and interporphyrin stacking of the type which is commonly observed in the structures of tetraphenylporphyrin derivatives. In the absence of a metal center, the basic functionality of the pyridyl substituents is utilized for effective H-bond directed coordination and co-crystallization with solvent/guest components. The stoichiometry of the porphyrin solvation, and the consequent interporphyrin organization in the solid phase, are quite sensitive to the nature of the coordinating solvent.

Synthesis, structure, and reactions of chiral rhenium vinylidene and acetylide complexes of the formula [(.eta.5-C5H5)Re(NO)(PPh3)(X)]n+. Vinylidene complexes that are formed by stereospecific C.beta. electrophilic attack, exist as two Re=C=C geometric isomers, and undergo stereospecific C.alpha. nucleophilic attack

In this paper, the authors report (a) high-yield syntheses of chiral rhenium vinylidene complexes ((/eta//sup 5/-C/sub 5/H/sub 5/)Re(NO)(PPh/sub 3/)(/emdash/C/emdash/CRR/prime/))/sup +/X/sup /minus// and acetylide complexes (/eta//sup 5/-C/sub 5/H/sub 5/)Re(NO)(PPh/sub 3/)(C/identical to/CR), (b) the first observation of M/emdash/C/emdash/C geometric isomerism in vinylidene complexes, (c) the thermal and photochemical interconversion of these geometric isomers and the corresponding rates and activation parameters, (d) examples of stereospecific C/sub /alpha// nucleophilic attack upon the vinylidene complexes and stereospecific C/sub /beta// electrophilic attack upon the acetylide complexes, and (e) X-ray crystal structures that establish the stereochemistry of these transformations and bonding features of both types of complexes. A portion of this study has been communicated.

Supramolecular Assembly of Functionalized Metalloporphyrins. Porous Crystalline Networks of Zinc-Tetra(4-Carboxyphenyl)Porphyrin

Abstract Two crystalline compounds based on the Zn-tetra (4-carboxyphenyl)porphyrin building block have been prepared and structurally analysed by x-ray diffraction in order to ellucidate the characteristic supramolecular aggregation modes of this functionalized metalloporphyrin moiety. Crystals of the 1:1 complex with sec-phenethyl alcohol (1) are monoclinic, space group I2/a (No. 15), a = 14.420(1), b = 24.678(2), c = 33.688(2) A, β = 90.03(2)°, Dc = 1.082 g/cm3, Z = 8, R = 0.080 for 3053 data. Those of the 1:3 complex with dimethylsulphoxide (2) are monoclinic, space group P21/n (No. 14), a = 14.881(1), b = 8.986(2), c = 37.550(3) A, β = 94.21(1)°, Dc = 1.444 g/cm3, Z = 4, R = 0.093 for 4200 data. The two compounds consist of nearly square-pyramidal five-coordinate metalloporphyrin species, molecules of the sec-phenethyl alcohol (in 1) and dimethylsulphoxide (in 2) linking to the metal center at the axial site. In 2, two additional molecules of dimethylsulphoxide associate through H-bonds to the termin...

Polyethylene powder as a stationary phase for preparative-scale reversed-phase high-performance liquid chromatography

Abstract Polyethylene powder has been shown to function effectively as a stationary phase in reversed-phase high-performance liquid chromatography. The low cost and durability of this material make it particularly attractive for use in preparative-scale separations. The applicability of preparative reversed-phase techniques to difficult separations of natural products is demonstrated by the isolation and separation of bacteriochlorophylls from green sulfur bacteria.

X-Ray crystal structure and chemical transformations of the neutral metal formyl [(η-C5H5)Re(PPh3)(NO)(CHO)]

The first X-ray crystallographic analysis of a metal complex containing a formyl ligand (1) and its reactions at room temperature with electrophiles and reducing agents are described.

Porphyrin Sponges: Programmable Lattice Clathrates

Abstract Structural systematics, programmability, and guest transport are discussed for a large class of lattice clathrates based on tetraarylporphyrins.

Cyloadditions of benzopyrones: Rapid access to bicyclic AB-ring analogues of anthracyclines

Abstract Cycloaddition of the benzopyrone 10b with 1,1-disubstituted alkenes 12 , 14 , and 16 produces fair yields of the lactones 13 , 15 , and 17 , AB-ring analogues of the anthracyclines.

Variable‐temperature accessory for use with a four‐circle x‐ray diffractometer

A nitrogen‐stream, low‐temperature accessory has been constructed for a four‐circle x‐ray diffractometer. This device features a glass transfer line with swivel joints that allow the nitrogen stream to follow the motion of the goniometer‐head axis during data collection. These joints are of simple construction and immune to ice formation even under conditions of high ambient humidity.

g-Tensor determination from single-crystal ESR data

Abstract A general method is presented for extraction of the g tensor from single-crystal electron spin resonance data. This method does not depend on knowledge of crystal morphology or on the presence of crystallographic symmetry. The g values are obtained from rotations around three arbitrarily chosen but accurately known axes.