New polynuclear manganese clusters from the use of the hydrophobic carboxylate ligand 2,2-dimethylbutyrate.

The syntheses, structures, and magnetic properties are reported of [Mn12O12(O2CPe(t))16(MeOH)4] (4), [Mn6O2(O2CH2)(O2CPe(t))11(HO2CPe(t))2(O2CMe)] (5), [Mn9O6(OH)(CO3)(O2CPe(t))12(H2O)2] (6), and [Mn4O2(O2CPe(t))6(bpy)2] (7, bpy = 2,2'-bipyridine), where Pe(t) = tert-pentyl (Pe(t)CO2H = 2,2-dimethylbutyric acid). These complexes were all prepared from reactions of [Mn12O12(O2CPe(t))16(H2O)4] (3) in CH2Cl2. Complex 4 x 2MeCN crystallizes in the triclinic space group P1 and contains a central [Mn(IV)4O4] cubane core that is surrounded by a nonplanar ring of eight alternating Mn(III) and eight mu3-O(2-) ions.

Synthesis, characterization, and physicochemical properties of manganese(III) and manganese(V)-oxo corrolazines.

The structural and physicochemical properties of the manganese-corrolazine (Cz) complexes (TBP8Cz)Mn(V)O (1) and (TBP8Cz)Mn(III) (2) (TBP = p-tert-butylphenyl) have been determined. Recrystallization of 2 from toluene/MeOH resulted in the crystal structure of (TBP8Cz)Mn(III)(CH3OH) (2 x MeOH). The packing diagram of 2 x MeOH reveals hydrogen bonds between MeOH axial ligands and meso N atoms of adjacent molecules.

Regioselective routes to disubstituted dibenzo crown ethers and their complexations.

Two isomers of bis(carbomethoxybenzo)-24-crown-8 (cis-BCMB24C8, 1, and trans-BCMB24C8, 2) were synthesized regiospecifically with acceptable to excellent yields. Cyclization in the presence of a template reagent, KPF(6), led to an essentially quantitative yield of the potassium complex of the crown ether 1; the isolated cyclization yield of pure was a remarkable 89%! The methods not only avoid the very difficult separation of the isomers, but also greatly shorten the synthesis time by eliminating syringe pump usage during cyclization. The complexations of the isomeric BCMB24C8 with dibenzylammonium hexafluorophosphate (10) were studied by NMR; association constants (Ka) for 1 and 2 with the dibenzylammonium cation are 190 and 312 M(-1), respectively.

Single-molecule magnets: high-field electron paramagnetic resonance evaluation of the single-ion zero-field interaction in a Zn(II)3Ni(II) complex.

High-field electron paramagnetic resonance spectra were collected at several frequencies for a single crystal of [Zn3.91Ni0.09(hmp)4(dmb)4Cl4] (1), where dmb is 3,3-dimethyl-1-butanol and hmp- is the monoanion of 2-hydroxymethylpyridine.

N-H...S hydrogen bonds in a ferredoxin model.

The Fe4S4 complex {(CH3)3NCH2CONH2}2[Fe4S4((tBuS)4] (1) was synthesized to replicate the ferredoxin active site with a subset of its N-H...

One-dimensional chain of tetranuclear manganese single-molecule magnets.

A one-dimensional chain of interconnected single-molecule magnets (SMMs) is obtained that consists of [Mn(4)(hmp)(6)](4+) units bridged by chloride ions. Slow magnetization relaxation is evident in the AC susceptibility data and in magnetization hysteresis measurements for [Mn(4)(hmp)(6)Cl(2)](n)(ClO(4))(2)(n). The magnetization hysteresis loops for this complex are similar to those for an SMM and show significant coercive field and steps at regular magnetic intervals.

Carbon-fluorine bond activation coupled with carbon-carbon bond formation at iridium. Confirmation of complete kinetic diastereoselectivity at the new carbon stereocenter by intramolecular trapping using vinyl as the migrating group.

The iridium(perfluoropropyl)(vinyl) complex CpIr(PMe(3))(n-C(3)F(7))(CH=CH(2)) (5) has been prepared. It has been characterized by X-ray crystallography, and its ground state conformation in solution has been determined by (19)F{(1)H} HOESY NMR studies. It reacts with the weak acid lutidinium iodide to afford the eta(1)-allylic complex CpIr(PMe(3))((Z)-CH(2)CH=CFC(2)F(5))I (6), which has also been characterized crystallographically.

Substrate oxidation by copper-dioxygen adducts: mechanistic considerations.

A series of copper-dioxygen adducts [{Cu(II)(MePY2)(R)}(2)(O(2))](B(C(6)F(5))(4))(2) (1(R)()), systematically varying in their electronic properties via ligand pyridyl donor substituents (R = H, MeO, and Me(2)N), oxidize a variety of substrates with varying C-H or O-H bond dissociation enthalpies. Detailed mechanistic studies have been carried out, including investigation of 1(R)() thermodynamic redox properties, 1(R)() tetrahydrofuran (THF) and N,N'-dimethylaniline (DMA) oxidation kinetics (including analyses of substrate dicopper binding equilibria), and application of mechanistic probes (N-cyclopropyl-N-methylaniline (CMA) and (p-methoxyphenyl)-2,2-dimethylpropanol (MDP)), which can distinguish if proton-coupled electron-transfer (PCET) processes proceed through concerted electron-transfer proton-transfer (ETPT) or consecutive electron-transfer proton-transfer (ET/PT) pathways. The results are consistent with those of previous complementary studies; at low thermodynamic driving force for substrate oxidation, an ET/PT is operable, but once ET (i.

Bis(m-phenylene)-32-crown-10-based cryptands, powerful hosts for paraquat derivatives.

Four new bis(m-phenylene)-32-crown-10-based cryptands with different third bridges were prepared. Their complexes with paraquat derivatives were studied by proton NMR spectroscopy, mass spectrometry, and X-ray analysis. It was found that these cryptands bind paraquat derivatives very strongly.

Wheel-shaped [Mn12] single-molecule magnets.

The reaction of [Mn(12)O(12)(O(2)CCH(3))(16)(H(2)O)(4)].4H(2)O.2CH(3)COOH with n-methyldiethanol amine (H(2)mdea), n-ethyldiethanol amine (H(2)edea), or n-butyldiethanol amine (H(2)bdea) leads to the formation of wheel-shaped Mn(III)(6)Mn(II)(6) complexes with the general formula [Mn(12)(R)(O(2)CCH(3))(14)] (1, R = mdea; 2, R = edea; and 3, R = bdea).

Cuprophilic and pi-stacking interactions in the formation of supramolecular stacks from dicoordinate organocopper complexes.

The unsupported organocopper pyridine complexes C6F5Cu(py) (2) and [C6F5Cu]2(4,4'-bipy) (3) form supramolecular structures that are unprecedented in organocopper chemistry; one-dimensional chains of copper atoms with Cu...

Sulfoxide carbon-sulfur bond activation.

The alkynylsulfoxide, TMSCCSO(p-tolyl) (TMS = trimethylsilyl, tolyl = C6H4Me), undergoes reaction with (eta5-C5H5)Co(PPh3)2 at room temperature to give the cobaltosulfoxide complex, (C5H5)Co(PPh3)(eta1-CCTMS)[eta1-(S)-SO(p-tolyl)], which was characterized by X-ray crystallography. Exposure of this cobaltosulfoxide complex to oxygen gas leads to the formation of the corresponding metallosulfone complex, (C5H5)Co(PPh3)(eta1-CCTMS)[eta1-(S)-SO2(p-tolyl)], which was characterized by X-ray crystallography. Alternatively, in solution at room temperature, the metallosulfoxide is converted to a 1:4 mixture of the equatorial-equatorial and equatorial-axial bridging cobalt-thiolato dimers, {(C5H5)Co[mu-S(p-tolyl)]}2, respectively.

Binding cooperativity of two different Lewis acid groups at the edge of ferrocene.

The binding properties of heteronuclear bidentate Lewis acids, in which an organoboron and an organotin moiety are attached adjacent to each other at one of the Cp rings of ferrocene, have been studied. Treatment of [1,2-fc(SnMe2Cl)(BClMe)] (1-Cl) (fc = ferrocenediyl) with one equivalent of pyridine or 4-dimethylaminopyridine (DMAP) resulted in diastereoselective complexation of boron. Adducts 2 and 3 have been studied by multinuclear NMR, and the stereoselectivity of complexation was further confirmed by single crystal X-ray diffraction of 2.

Amide-ligand hydrogen bonding in reverse micelles.

One approach to modeling the second coordination shell of metalloproteins is to pair amide-containing counterions with metal complexes to form hydrogen bonds in the solid state. In a more general approach, we have designed a surfactant counterion that can sustain hydrogen bonding interactions with metal complexes in solution. The surfactant is cationic and incorporates an amide as part of its headgroup to form hydrogen.

Preliminary evaluation of a video-based intervention for older adult victims of violence.

The present study evaluated a brief, video-based intervention for older adults designed to: provide psychological education regarding common reactions to crime; offer information about healthy coping strategies to manage crime-related symptomatology; and increase awareness of effective safety planning strategies. Following reporting to police, 116 older adult crime victims were randomly assigned to receive either standard advocate-based services plus the video-based intervention or standard advocate services alone. Results indicated that older adult victims assigned to the video condition and assessed later that day exhibited greater awareness of crime-related symptoms, healthy coping strategies, and safety planning strategies than did the older adult victims assigned to standard practice of care.

Aurophilic interactions in mu-p-phenylenediethynyl-bis[(trimethyl phosphite)gold(I)] dichloromethane hemisolvate.

The title compound, [Au2(C10H4)(C3H9O3P)2].0.5CH2Cl2, is a linear monomer in which each Au atom is coordinated by one acetylene and one phosphite group.

Single-molecule magnets: structure and properties of [Mn18O14(O2CMe)18(hep)4(hepH)2(H2O)2](ClO4)2 with spin S = 13.

The reaction of 2-(hydroxyethyl)pyridine (hepH) with a 2:1 molar mixture of [Mn3O(O2CMe)6(py)3]ClO4 and [Mn3O(O2CMe)6(py)3] in MeCN afforded the new mixed-valent (16Mn(III), 2Mn(II)), octadecanuclear complex [Mn18O14(O2CMe)18(hep)4(hepH)2(H2O)2](ClO4)2 (1) in 20% yield. Complex 1 crystallizes in the triclinic space group P. Direct current magnetic susceptibility studies in a 1.

Binuclear ruthenium macrocycles formed via the weak-link approach.

The "weak-link approach" for the synthesis of metallomacrocycles has been used to synthesize a series of novel Ru(II) macrocycles in high yield. RuCl2(PPh3)3 has been reacted with two different phosphino-alkyl-ether hemilabile ligands, 1,4-(PPh2(CH2)2O)2C6H4 and 1,4-(PPh2(CH2)2OCH2)2C6H4. The hemilabile bidentate ligand coordinates to Ru(II) centers through both the P and O atoms to form bimetallic "condensed intermediates".

Synthesis of a symmetric cylindrical bis(crown ether) host and its complexation with paraquat.

The first cylindrical host for paraquat derivatives was prepared and characterized by X-ray analysis. Its complex with paraquat has 1:2 stoichiometry. The complexation is statistical and strong as shown by proton NMR characterization, electrospray mass spectrometry, and X-ray analysis.

A chromium catalyst for the polymerization of ethylene as a homogeneous model for the phillips catalyst.

A structurally characterized cationic chromium(III) alkyl featuring a bulky nacnac ligand catalyzes the polymerization of ethylene as well as the copolymerization of ethylene with alpha-olefins. This well-characterized homogeneous catalyst constitutes a structural as well as functional model of the widely used heterogeneous Phillips olefin polymerization catalyst.

Insertion reactions of carbon dioxide into Zn-N bonds: syntheses and structures of tetrameric and dimeric alkylzinc carbamato complexes.

The formal insertions of carbon dioxide into a series of methylzinc dialkylamide complexes (MeZnNR(2)) initially form solvent-free, tetrameric zinc carbamato complexes [Me(4)Zn(4)(O(2)CNR(2))(4)] (NR(2) = N(i-Pr)(2) (1), N(i-Bu)(2) (2), and piperidinyl (3)). These compounds have been characterized by traditional techniques as well as by single-crystal X-ray diffraction analyses. The tetrameric backbones seen in the solid state for 1-3 were structurally similar to each other.

Heteroligated metallomacrocycles generated via the weak-link approach.

Sequential reaction of two different hemilabile ligands (Ph(2)PCH(2)CH(2)X)(2)Ar (X = S, Ar = C(6)H(4) or C(6)(CH(3))(4); X = NCH(3), Ar = C(6)H(4); X = O, Ar = 9,10-C(14)H(8)) with a Rh(I) metal center resulted in the formation of heteroligated metallomacrocycles in high yield. The specific reaction conditions for each pair of hemilabile ligands are discussed. The solid-state structure of [[1,4-(Ph(2)PCH(2)CH(2)S)(2)C(6)H(4)]-[1,4-(Ph(2)PCH(2)CH(2)S)(2)C(6)(CH(3))(4)]Rh(2)](BF(4))(2), as determined by X-ray crystallography, is presented.

Manganese(I) poly(mercaptoimidazolyl)borate complexes: spectroscopic and structural characterization of Mn...H-B interactions in solution and in the solid state.

The manganese(I) tricarbonyl complexes (Bm(R))Mn(CO)3(R = Me, Bz, But, p-Tol) and (PhBmMe)Mn(CO)3, the first bis(mercaptoimidazolyl)borate derivatives for this metal, have been readily prepared and fully characterized. In particular, the presence of three-center-two-electron Mn..

Heme-copper/dioxygen adduct formation relevant to cytochrome c oxidase: spectroscopic characterization of [(6L)FeIII-(O2(2-))-CuII]+.

In the further development and understanding of heme-copper dioxygen reactivity relevant to cytochrome c oxidase O(2)-reduction chemistry, we describe a high-spin, five-coordinate dioxygen (peroxo) adduct of an iron(II)-copper(I) complex, [((6)L)Fe(II)Cu(I)](BArF(20)) (1), where (6)L is a tetraarylporphyrinate with a tethered tris(2-pyridylmethyl)amine chelate for copper. Reaction of 1 with O(2) in MeCN affords a remarkably stable [t(1/2) (rt; MeCN) approximately 60 min] adduct, [((6)L)Fe(III)-(O(2) (2-))-Cu(II)](+) (2) [EPR silent; lambda(max)=418 (Soret), 561 nm], formulated as a peroxo complex based on manometry (1:O(2)=1:1; spectrophotometric titration, -40 degrees C, MeCN), mass spectrometry {MALDI-TOF-MS: (16)O(2), m/z 1191 ([((6)L)Fe(III)-((16)O(2) (2-))-Cu(II)](+)); (18)O(2), m/z 1195}, and resonance Raman spectroscopy (nu((O-O))=788 cm(-1); Delta(16)O(2)/(18)O(2)=44 cm(-1); Delta(16)O(2)/(16/18)O(2)=22 cm(-1)). (1)H and (2)H NMR spectroscopy (-40 degrees C, MeCN) reveals that 2 is the first heme-copper peroxo complex which is high-spin, with downfield-shifted pyrrole resonances (delta(pyrrole)=75 ppm, s, br) and upfield shifted peaks at delta= -22, -35, and -40 ppm, similar to the pattern observed for the mu-oxo complex [((6)L)Fe(III)-O-Cu(II)](BAr(F)) (3) (known S=2 system, antiferromagnetically coupled high-spin Fe(III) and Cu(II)).