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1.
Int J STD AIDS ; 29(11): 1146-1150, 2018 11.
Article in English | MEDLINE | ID: mdl-29743005

ABSTRACT

This national audit demonstrated discrepancies between actual practice and that indicated by clinic policies following enquiry about alcohol, recreational drugs and chemsex use. Clinics were more likely to enquire about risk behaviour if this was clinic policy or routine practice. Previous testing was the most common reason for refusing HIV testing, although 33% of men who have sex with men had a prior test of more than three months ago. Of the group declining due to recent exposure in the window period, 21/119 cases had an exposure within the four weeks prior to presentation, but had a previous risk not covered by previous testing. Recommendations include provision of risk assessments for alcohol, recreational drug use and chemsex, documenting reasons for HIV test refusal, provision of HIV point-of-care testing, follow-up for cases at higher risk of HIV and advice about community testing or self-sampling/testing.


Subject(s)
AIDS Serodiagnosis/statistics & numerical data , Clinical Audit , Guideline Adherence , Homosexuality, Male , Illicit Drugs , Mass Screening/statistics & numerical data , Practice Guidelines as Topic , Substance-Related Disorders/complications , Humans , Male , Risk Assessment , Sexual Behavior , United Kingdom
2.
Dalton Trans ; 41(37): 11311-8, 2012 Oct 07.
Article in English | MEDLINE | ID: mdl-22886043

ABSTRACT

A new molecular adduct of MgCl(2) with isobutanol, namely MgCl(2)·4((CH(3))(2)CHCH(2)OH) (MgiBOH), has been prepared as a precursor to the supporting material for an olefin polymerization catalyst. The MgiBOH adduct and final titanated Ziegler-Natta catalysts have been thoroughly characterized by powder XRD, thermal analysis, Raman spectroscopy and solid-state NMR for structural and spectroscopy aspects. A peak observed at 712 cm(-1) in the Raman spectra of MgiBOH indicates the characteristic Mg-O(6) breathing mode and the formation of the adduct. The diffraction feature at 2θ = 7.8° (d = 11.223 Å) in the XRD confirms the adduct formation and the layered structure. The aim of the present article is to study how the insertion of a bulky isobutanol moiety affects the structural and electronic properties of the MgCl(2)·isobutanol molecular adduct. Indeed, the focus of the present study is to explore how the presence of isobutanol, in the initial molecular adduct, influences the final Z-N catalyst properties and its activity.

4.
Dalton Trans ; 40(41): 10936-44, 2011 Nov 07.
Article in English | MEDLINE | ID: mdl-21909567

ABSTRACT

Benzyl alcohol has been used to prepare a single phase MgCl(2).6BzOH molecular adduct as a support for an ethylene polymerization catalyst (Ziegler catalyst). The structural, spectroscopic and morphological aspects of the MgCl(2).6BzOH molecular adduct and the Ziegler catalyst have been thoroughly studied by various physicochemical characterization techniques. The presence of MgO(6) octahedrons due to the interaction of Mg(2+) with six -OH groups of the benzyl alcohol is confirmed from a Raman feature at 703 cm(-1), and structural studies. The supported catalyst activity has been evaluated for the ethylene polymerization reaction. The lower polymerization activity of the titanated Ziegler-Natta catalyst compared with a standard catalyst is attributed to the strong interaction of titanium chloride with the support and associated electronic factors.

5.
J Ind Microbiol Biotechnol ; 35(12): 1559-70, 2008 Dec.
Article in English | MEDLINE | ID: mdl-18716809

ABSTRACT

Mannosylerythritol lipids (MELs) are surface active compounds that belong to the glycolipid class of biosurfactants (BSs). MELs are produced by Pseudozyma sp. as a major component while Ustilago sp. produces them as a minor component. Although MELs have been known for over five decades, they recently regained attention due to their environmental compatibility, mild production conditions, structural diversity, self-assembling properties and versatile biochemical functions. In this review, the MEL producing microorganisms, the production conditions, their applications, their diverse structures and self-assembling properties are discussed. The biosynthetic pathways and the regulatory mechanisms involved in the production of MEL are also explained here.


Subject(s)
Glycolipids/chemistry , Surface-Active Agents/chemistry , Glycolipids/biosynthesis , Molecular Conformation , Ustilaginales/metabolism
6.
Int J STD AIDS ; 19(7): 473-6, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18574120

ABSTRACT

Verbal information-giving is good, but only half of cases were reportedly given written information on chlamydia. Follow-up by 'phoning or texting (43%) was as common as follow-up in clinics (39%). About one-fourth of cases did not have follow up, with no recall for around 60% of these cases. Advice about partner notification (PN) was provided by a health adviser or other suitably trained health professional to 91% of cases, and the method of PN was documented for 92% of these cases. PN outcome was not documented for about 25% of these cases. There was no information on the chlamydial status of sexual contacts of about half of cases, and no information about the treatment status of sexual contacts of about 40% of cases. The average number of contacts screened per index was 0.52 outside London and 0.29 for the London Regions, levels below those suggested in the National Guideline.


Subject(s)
Ambulatory Care Facilities , Chlamydia Infections/prevention & control , Contact Tracing , Medical Audit , Patient Education as Topic/methods , Sexually Transmitted Diseases/prevention & control , Anti-Bacterial Agents/administration & dosage , Anti-Bacterial Agents/therapeutic use , Chlamydia Infections/drug therapy , Chlamydia Infections/epidemiology , Chlamydia Infections/microbiology , Chlamydia trachomatis/drug effects , Female , Female Urogenital Diseases/drug therapy , Female Urogenital Diseases/epidemiology , Female Urogenital Diseases/prevention & control , Follow-Up Studies , Humans , Male , Male Urogenital Diseases/drug therapy , Male Urogenital Diseases/epidemiology , Male Urogenital Diseases/prevention & control , Sexual Partners , Sexually Transmitted Diseases/drug therapy , Sexually Transmitted Diseases/epidemiology , Telephone , Treatment Outcome , United Kingdom
7.
Int J STD AIDS ; 19(7): 477-9, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18574121

ABSTRACT

There was a wide range of activity and chlamydial diagnoses between the 177 clinics that responded. Most (92%) clinics have nucleic acid tests for chlamydial diagnosis. Different practitioners largely share roles in providing advice to patients about partner notification, treatment adherence, safer sex advice and abstinence. Most (97%) clinics have information leaflets about chlamydia, although about 30% of clinics lack leaflets containing information about antibiotics and hormonal contraception. About two-third clinics follow the National Guideline recommended interval for providing a test of cure where this is indicated. Only 18% of clinics routinely ask patients to reattend, with 40% having a policy of no routine follow-up and 62% using telephone or text follow-up. These categories were not mutually exclusive. Most (86%) of the 146 English clinics had a local Chlamydia Screening Programme coordinator for their Primary Care Trust area, although cooperation varies, with cooperation over treatment of 70% and Programme policy of 62%.


Subject(s)
Ambulatory Care Facilities , Chlamydia Infections , Health Policy , Medical Audit , Sexually Transmitted Diseases/prevention & control , Chlamydia Infections/diagnosis , Chlamydia Infections/drug therapy , Chlamydia Infections/prevention & control , Delivery of Health Care/methods , Female , Female Urogenital Diseases/diagnosis , Female Urogenital Diseases/drug therapy , Female Urogenital Diseases/prevention & control , Humans , Male , Male Urogenital Diseases/drug therapy , Male Urogenital Diseases/prevention & control , Sexually Transmitted Diseases/diagnosis , Sexually Transmitted Diseases/drug therapy , United Kingdom
8.
Int J STD AIDS ; 19(7): 469-72, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18574119

ABSTRACT

The case notes of cases of genital chlamydial infection were audited against the UK National Guideline. This was the first web-based and the largest national audit to date, with 193 clinics in all UK Regions contributing data. About half of all cases had no symptoms, with about one-third attending for routine or asymptomatic screens; suggesting significant provision of screening by clinics that might be managed differently to reduce workload. Nucleic acid amplification tests (NAATs) are now well established for chlamydial detection in UK clinics, with 93% of cases having genital NAATs. Azithromycin is now more commonly used than doxycycline (54% vs. 37%). Of 26 pregnant women, 20 were treated with azithromycin, suggesting that most prescribers treating pregnant women consider that erythromycin is not an adequate alternative to azithromycin. Most women had NAATs obtained from sites recommended by the Guideline, with 93% of women who had genital NAATs having these from the cervix or vulvovaginal area.


Subject(s)
Ambulatory Care Facilities , Chlamydia Infections , Chlamydia trachomatis/isolation & purification , Medical Audit , Sexually Transmitted Diseases/prevention & control , Adolescent , Adult , Aged , Anti-Bacterial Agents/therapeutic use , Azithromycin/therapeutic use , Chlamydia Infections/diagnosis , Chlamydia Infections/drug therapy , Chlamydia Infections/epidemiology , Chlamydia trachomatis/drug effects , Chlamydia trachomatis/genetics , Female , Female Urogenital Diseases/diagnosis , Female Urogenital Diseases/drug therapy , Female Urogenital Diseases/epidemiology , Humans , Male , Male Urogenital Diseases/diagnosis , Male Urogenital Diseases/drug therapy , Male Urogenital Diseases/epidemiology , Middle Aged , Nucleic Acid Amplification Techniques , Pregnancy , Pregnancy Complications, Infectious/diagnosis , Pregnancy Complications, Infectious/drug therapy , Pregnancy Complications, Infectious/epidemiology , Treatment Outcome , United Kingdom
10.
Dalton Trans ; (24): 2594-8, 2007 Jun 28.
Article in English | MEDLINE | ID: mdl-17563796

ABSTRACT

Artificial electron donors such as leuco methylene blue and leuco safranin O reduce nitrite ion to nitric oxide. The reaction is effected in a U-tube where nitrite ion and dye in two aqueous layers are separated by a layer of dichloromethane (a close model for a biological liquid membrane) that contains the platinum carbonyl cluster ([Bu(4)N]2[Pt12(CO)24], Chini cluster). On passing dihydrogen an electron transfer chain involving dihydrogen, the dye, the clusters and the nitrite ion is initiated. The cluster catalytically reduces the dye in the presence of dihydrogen, the reduced dye migrates across the phase boundaries and in turn reduces the nitrite ions. The resultant nitric oxide in the effluent gas has been identified by its reactions with cobalamine and myoglobin. When safranin O is the dye, an adduct is formed between the reduced dye and NO. It has been identified by spectroscopic techniques and its probable structure investigated by DFT calculations.


Subject(s)
Electrons , Nitric Oxide/chemistry , Nitrites/chemistry , Platinum Compounds/chemistry , Catalysis , Coloring Agents , Electron Spin Resonance Spectroscopy , Gases/analysis , Indicators and Reagents , Methylene Blue , Models, Molecular , Oxidation-Reduction , Spectrometry, Mass, Electrospray Ionization , Spectrophotometry, Infrared , Spectrophotometry, Ultraviolet
11.
J Phys Chem B ; 111(15): 3877-85, 2007 Apr 19.
Article in English | MEDLINE | ID: mdl-17388623

ABSTRACT

The covalent linkages formed during functionalization of MCM-41 mesoporous molecular sieves with five chloroalkylsilanes ((EtO)3Si(CH2Cl), (MeO)3Si(CH2CH2CH2Cl), Cl3Si(CH2CH2CH3), Cl2Si(CH3)(CH2Cl) and Cl2Si(CH3)2) have been investigated using high-resolution solid-state NMR spectroscopy and DFT calculations. Structural information was obtained from 1H-13C and 1H-29Si heteronuclear (HETCOR) NMR spectra, in which high resolution in the 1H dimension was obtained by using fast MAS. The 1H-13C HETCOR results provided the assignments of 1H and 13C resonances associated with the surface functional groups. Sensitivity-enhanced 1H-29Si HETCOR spectra, acquired using Carr-Purcell-Meiboom-Gill refocusing during data acquisition, revealed the identity of 29Si sites (Qn, Tn, and Dn) and the location of functional groups relative to these sites. Optimal geometries of local environments representing the Qn, Tn and Dn resonances were calculated using molecular mechanics and ab initio methods. Subsequently, DFT calculations of 29Si, 13C, and 1H chemical shifts were performed using Gaussian 03 at the B3LYP/6-311++G(2d,2p) level. The theoretical calculations are in excellent accord with the experimental chemical shifts. This work illustrates that state-of-the-art spectroscopic and theoretical tools can be used jointly to refine the complex structures of inorganic-organic hybrid materials.


Subject(s)
Magnetic Resonance Spectroscopy/methods , Models, Chemical , Silicon Dioxide/chemistry , Carbon Isotopes , Isotopes , Porosity , Protons , Sensitivity and Specificity , Silicon
12.
J Am Chem Soc ; 127(6): 1933-45, 2005 Feb 16.
Article in English | MEDLINE | ID: mdl-15701028

ABSTRACT

The construction of a synthetic analogue of the A-cluster of carbon monoxide dehydrogenase/acetylcoenzyme synthase, the site of acetylcoenzyme A formation, requires as a final step the formation of an unsupported [Fe(4)S(4)]-(mu(2)-SR)-Ni(II) bridge to a preformed cluster. Our previous results (Rao, P. V.; Bhaduri, S.; Jiang, J.; Holm, R. H. Inorg. Chem. 2004, 43, 5833) and the work of others have addressed synthesis of dinuclear complexes relevant to the A-cluster. This investigation concentrates on reactions pertinent to bridge formation by examining systems containing dinuclear and mononuclear Ni(II) complexes and the 3:1 site-differentiated clusters [Fe(4)S(4)(LS(3))L'](2-) (L' = TfO(-) (14), SEt (15)). The system 14/[{Ni(L(O)-S(2)N(2))}M(SCH(2)CH(2)PPh(2))](+) results in cleavage of the dinuclear complex and formation of [{Ni(L(O)-S(2)N(2))}Fe(4)S(4)(LS(3))]- (18), in which the Ni(II) complex binds at the unique cluster site with formation of a Ni(mu(2)-SR)(2)Fe bridge rhomb. Cluster 18 and the related species [{Ni(phma)}Fe(4)S(4)(LS(3))](3)- (19) are obtainable by direct reaction of the corresponding cis-planar Ni(II)-S(2)N(2) complexes with 14. The mononuclear complexes [M(pdmt)(SEt)]- (M = Ni(II), Pd(II)) with 14 in acetonitrile or Me(2)SO solution react by thiolate transfer to give 15 and [M(2)(pdmt)(2)]. However, in dichloromethane the Ni(II) reaction product is interpreted as [{Ni(pdmt)(mu(2)-SEt)}Fe(4)S(4)(LS(3))](2-) (20). Reaction of Et(3)NH(+) and 15 affords the double cubane [{Fe(4)S(4)(LS(3))}(2)(mu(2)-SEt)](3-) (21). Cluster 18 contains two mutually supportive Fe-(mu(2)-SR)-Ni(II) bridges, 19 exhibits one strong and one weaker bridge, 20 has one unsupported bridge (inferred from the (1)H NMR spectrum), and 21 has one unsupported Fe-(mu(2)-SR)-Fe bridge. Bridges in 18, 19, and 21 were established by X-ray structures. This work demonstrates that a bridge of the type found in the enzyme A-clusters is achievable by synthesis and implies that more stable, unsupported single thiolate bridges may require reinforcement by an additional covalent linkage between the Fe(4)S(4) and nickel-containing components. (LS(3) = 1,3,5-tris((4,6-dimethyl-3-mercaptophenyl)thio)-2,4,6-tris(p-tolylthio)benzene(3-); L(O)-S(2)N(2) = N,N'-diethyl-3,7-diazanonane-1,9-dithiolate(2-); pdmt = pyridine-2,6-methanedithiolate(2-); phma = N,N'-1,2-phenylenebis(2-acetylthio)acetamidate(4-); TfO = triflate.).


Subject(s)
Acetate-CoA Ligase/chemical synthesis , Aldehyde Oxidoreductases/chemical synthesis , Iron-Sulfur Proteins/chemical synthesis , Multienzyme Complexes/chemical synthesis , Acetate-CoA Ligase/chemistry , Aldehyde Oxidoreductases/chemistry , Biomimetic Materials/chemical synthesis , Biomimetic Materials/chemistry , Iron-Sulfur Proteins/chemistry , Models, Molecular , Multienzyme Complexes/chemistry , Nickel/chemistry , Nuclear Magnetic Resonance, Biomolecular , Organometallic Compounds/chemical synthesis , Organometallic Compounds/chemistry , Organoplatinum Compounds/chemical synthesis , Organoplatinum Compounds/chemistry
14.
Inorg Chem ; 43(19): 5833-49, 2004 Sep 20.
Article in English | MEDLINE | ID: mdl-15360232

ABSTRACT

Sulfur bridging interactions between three cis-planar NiII-S2N2 complexes and NiII, CuI,II, ZnII, and HgII reactants were investigated by synthesis and X-ray crystal structures of some 24 complexes. This work was stimulated by recent crystallographic structures of the A-cluster of carbon monoxide dehydrogenase/acetylcoenzyme A synthase. This bridged biological assembly has the minimal formulation [Fe4S4]-(micro2-SCys)-[M((micro2-SCys)2Gly)Ni] with M = NiII, CuI, and ZnII at sites distal and proximal, respectively, to the iron-sulfur cluster. Bridges supported by representations of the distal nickel site were sought by reactions of the complexes [NiII(LH-S2N2)]2- and [NiII(LR-S2N2)], with 5-5-5 chelate ring patterns. Reaction products implicate the bridges Ni-(micro2-S)1,2-M in a variety of molecular structures, some with previously unknown connectivities of bridge atoms. The most frequently encountered bridge units are the nonplanar rhombs Ni(2-S)2M involving both sulfur atoms of a given complex. Those with M = NiII are biologically relevant inasmuch as the catalytic metal at the proximal site is nickel. The complex [Ni(L-655)]2-, containing the 6-5-5 ring pattern and coordination sphere of the distal nickel site, was prepared and structurally characterized. It was shown to sustain Ni2(micro2-S)2 rhombic interactions in the form of trinuclear [[Ni(L-655)]2Ni]2- and [[Ni(L-655)]Ni(R2PCH2CH2PR2)] (R = Et, Ph) in which the second NiII simulates the proximal site. Bridging interactions of NiII-S2N2 complexes are summarized, and geometrical features of Ni2(2-S)2 rhombs in these complexes, as dependent on ring patterns, are considered (LH-S2N2 = N,N'-ethylenebis(2-mercaptoisobutyramide)(4-); LR-S2N2 = trans-rac-N,N'-bis(2-mercapto-2-methylprop-1-yl)-1,2-cyclohexanediamine(2-); L-655 = N-(2-mercaptopropyl)-N'-(2'-mercaptoethyl)glycinamide(4-)).


Subject(s)
Bridged-Ring Compounds/chemistry , Bridged-Ring Compounds/chemical synthesis , Copper/chemistry , Nickel/chemistry , Organometallic Compounds/chemistry , Organometallic Compounds/chemical synthesis , Sulfur/chemistry , Zinc/chemistry , Crystallography, X-Ray , Iron/chemistry , Mercury/chemistry , Molecular Conformation , Nitrogen/chemistry , Silver/chemistry
16.
Inorg Chem ; 42(5): 1483-92, 2003 Mar 10.
Article in English | MEDLINE | ID: mdl-12611514

ABSTRACT

The synthesis of new dinuclear manganese(IV) complexes possessing the [Mn(IV)(2)(mu-O)(2)(mu-O(2)CMe)](3+) core and containing halide ions as terminal ligands is reported. [Mn(2)O(2)(O(2)CMe)Cl(2)(bpy)(2)](2)[MnCl(4)] (1; bpy = 2,2'-bipyridine) was prepared by sequential addition of [MnCl(3)(bpy)(H(2)O)] and (NBzEt(3))(2)[MnCl(4)] to a CH(2)Cl(2) solution of [Mn(3)O(4)(O(2)CMe)(4)(bpy)(2)]. The complex [Mn(IV)(2)O(2)(O(2)CMe)Cl(bpy)(2)(H(2)O)](NO(3))(2) (2) was obtained from a water/acetic acid solution of MnCl(2).4H(2)O, bpy, and (NH(4))(2)[Ce(NO(3))(6)], whereas the [Mn(IV)(2)O(2)(O(2)CR)X(bpy)(2)(H(2)O)](ClO(4))(2) [X = Cl(-) and R = Me (3), Et (5), or C(2)H(4)Cl (6); and X = F(-), R = Me (4)] were prepared by a slightly modified procedure that includes the addition of HClO(4). For the preparation of 4, MnF(2) was employed instead of MnCl(2).4H(2)O. [Mn(2)O(2)(O(2)CMe)Cl(2)(bpy)(2)](2)[MnCl(4)].2CH(2)Cl(2) (1.2CH(2)Cl(2)) crystallizes in the monoclinic space group C2/c with a = 21.756(2) A, b = 12.0587(7) A, c = 26.192(2) A, alpha = 90 degrees, beta = 111.443(2) degrees, gamma = 90 degrees, V = 6395.8(6) A(3), and Z = 4. [Mn(2)O(2)(O(2)CMe)Cl(H(2)O)(bpy)(2)](NO(3))(2).H(2)O (2.H(2)O) crystallizes in the triclinic space group Ponemacr; with a = 11.907(2) A, b = 12.376(2) A, c = 10.986(2) A, alpha = 108.24(1) degrees, beta = 105.85(2) degrees, gamma = 106.57(1) degrees, V = 1351.98(2) A(3), and Z = 2. [Mn(2)O(2)(O(2)CMe)Cl(H(2)O)(bpy)(2)](ClO(4))(2).MeCN (3.MeCN) crystallizes in the triclinic space group Ponemacr; with a = 11.7817(7) A, b = 12.2400(7) A, c = 13.1672(7) A, alpha = 65.537(2) degrees, beta = 67.407(2) degrees, gamma = 88.638(2) degrees, V = 1574.9(2) A(3), and Z = 2. The cyclic voltammogram (CV) of 1 exhibits two processes, an irreversible oxidation of the [MnCl(4)](2)(-) at E(1/2) approximately 0.69 V vs ferrocene and a reversible reduction at E(1/2) = 0.30 V assigned to the [Mn(2)O(2)(O(2)CMe)Cl(2)(bpy)(2)](+/0) couple (2Mn(IV) to Mn(IV)Mn(III)). In contrast, the CVs of 2 and 3 show only irreversible reduction features. Solid-state magnetic susceptibility (chi(M)) data were collected for complexes 1.1.5H(2)O, 2.H(2)O, and 3.H(2)O in the temperature range 2.00-300 K. The resulting data were fit to the theoretical chi(M)T vs T expression for a Mn(IV)(2) complex derived by use of the isotropic Heisenberg spin Hamiltonian (H = -2JS(1)S(2)) and the Van Vleck equation. The obtained fit parameters were (in the format J/g) -45.0(4) cm(-)(1)/2.00(2), -36.6(4) cm(-)(1)/1.97(1), and -39.3(4) cm(-)(1)/1.92(1), respectively, where J is the exchange interaction parameter between the two Mn(IV) ions. Thus, all three complexes are antiferromagnetically coupled.

18.
Inorg Chem ; 41(4): 805-17, 2002 Feb 25.
Article in English | MEDLINE | ID: mdl-11849081

ABSTRACT

New synthesis procedures are described to tetranuclear manganese carboxylate complexes containing the [Mn(4)O(2)](8+) or [Mn(4)O(3)X](6+) (X(-) = MeCO(2)(-), F(-), Cl(-), Br(-), NO(3)(-)) core. These involve acidolysis reactions of [Mn(4)O(3)(O(2)CMe)(4)(dbm)(3)] (1; dbm is the anion of dibenzoylmethane) or [Mn(4)O(2)(O(2)CEt)(6)(dbm)(2)] (8) with HX (X(-) = F(-), Cl(-), Br(-), NO(3)(-)); high-yield routes to 1 and 8 are also described. The X(-) = NO(3)(-) complexes [Mn(4)O(3)(NO(3))(O(2)CR)(3)(R'(2)dbm)(3)] (R = Me, R' = H (6); R = Me, R' = Et (7); R = Et, R' = H (12)) represent the first synthesis of the [Mn(4)O(3)(NO(3))](6+) core, which contains an unusual eta(1):mu(3)-NO(3)(-) group. Treatment of known [Mn(4)O(2)(O(2)CEt)(7)(bpy)(2)](ClO(4)) with HNO(3) gives [Mn(4)O(2)(NO(3))(O(2)CEt)(6)(bpy)(2)](ClO(4)) (15) containing a eta(1):eta(1):mu-NO(3)(-) group bridging the two body Mn(III) ions of the [Mn(4)O(2)](8+) butterfly core. Complex 7 x 4CH(2)Cl(2) crystallizes in space group P2(1)2(1)2(1) with (at -168 degrees C) a = 21.110(3) A, b = 22.183(3) A, c = 15.958(2) A, Z = 4, and V = 7472.4(3) A(3). Complex 15 x (3)/(2)CH(2)Cl(2) crystallizes in space group P2(1)/c with (at -165 degrees C) a = 26.025(4) A, b = 13.488(2) A, c = 32.102(6) A, beta = 97.27(1) degrees, Z = 8, and V = 11178(5) A(3). Complex 7 contains a [Mn(4)(mu(3)-O)(3)(mu(3)-NO(3))](6+) core (3Mn(III), Mn(IV)) as seen for previous [Mn(4)O(3)X](6+) complexes. Complex 15 contains a butterfly [Mn(4)(mu(3)-O)(2)](8+) core. (1)H NMR spectra have been recorded for all complexes reported in this work and the various resonances assigned. All complexes retain their structural integrity on dissolution in chloroform and dichloromethane. Magnetic susceptibility (chi(M)) data were collected on 12 in the 5-300 K range in a 10.0 kG (1 T) field. Fitting of the data to the theoretical chi(M) vs T expression appropriate for a [Mn(4)O(3)X](6+) complex of C(3)(v)() symmetry gave J(34) = -23.9 cm(-)(1), J(33) = 4.9 cm(-)(1), and g = 1.98, where J(34) and J(33) refer to the Mn(III)Mn(IV) and Mn(III)Mn(III) pairwise exchange interactions, respectively. The ground state of the molecule is S = 9/2, as found previously for other [Mn(4)O(3)X](6+) complexes. This was confirmed by magnetization data collected at various fields and temperatures. Fitting of the data gave S = 9/2, D = -0.45 cm(-1), and g = 1.96, where D is the axial zero-field splitting parameter.


Subject(s)
Carboxylic Acids/chemistry , Manganese Compounds/chemistry , Manganese Compounds/chemical synthesis , Manganese/chemistry , Nitrates/chemistry , Chemical Phenomena , Chemistry, Physical , Magnetic Resonance Spectroscopy , Models, Chemical , Molecular Conformation , Molecular Structure
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