Keith H. Pannell

Tin Chemistry: Fundamentals, Frontiers, and Applications

Tin chemistry retains a place in contemporary science as an important element owing to its wide range of applications. New and exciting research is being generated on an annual basis from all parts of the world - the study of tin and its compounds attracts considerable interest from a range of perspectives such as organic synthesis, medicine, materials chemistry, catalysis and environment. Tin Chemistry - Fundamentals, Frontiers and Applications collects, in one comprehensive volume, authoritative and concise snapshots of modern tin chemistry in a full range of applications. Over forty of the leading tin chemistry experts have contributed reviews in six themes: fundamentals in tin chemistry. Materials chemistry and structural. Chemistry of tin compounds. Medicinal and biocidal applications of tin compounds. Tin in the environment. Tin in organic synthesis. Tin in catalysis. Tin Chemistry - Fundamentals, Frontiers and Applications is an essential overview of modern perspectives on this important element for the specialist and non-specialist alike.

Some mixed-ligand complexes of copper(II) with drugs of the quinolone family and (NN) donors. Crystal structure of [Cu(phen)(Cnx)(H2O)]NO3 · H2O

Abstract The synthesis of eight new mixed-ligand complexes of Cu(II) of the type [Cu(NN)(Antb)]X is reported, where NN is 1,10-phenanthroline (phen) or 2,2′-bipyridine (bipy), Antb is the anion of cinoxacin (Cnx) or oxolinic acid (Oxo), both drugs of the quinolone family. The crystal structure of [Cu(phen)(Cnx)(H 2 O)NO 3 · H 2 O is presented and discussed. The results here reported together with those previously reported for the complex [Cu(phen)(Nal)(H 2 O)]NO 3 · 3H 2 O and preliminary crystal data for the complex [Cu(bipy)(Oxo)]NO 3 · H 2 O, suggest that all the quinolone type drugs behave in a similar way as ligands under equivalent conditions.

8-Amino-BODIPYs: structural variation, solvent-dependent emission, and VT NMR spectroscopic properties of 8-R2N-BODIPY.

New 8-NR2-BODIPYs, R2 = H(i)Pr (3a), H(i)Bu (3b), and Et2 (4), are reported. Restricted rotation about the C8-N bond in such molecules has been observed for the first time (3a and 3b) and evaluated using VT NMR. The fluorophores 3a and 3b are blue emitters, and the efficiency of the emission is closely related to the polarity of the solvent, e.g., hexane > toluene > DCM > THF > MeOH > H2O, an effect also noted by emission variation in alcohol solvents H(CH2)nOH, n = 1-6. In mixed-solvent systems, addition of 10-15% of the more polar solvent results in transformation of the emission properties to those of the bulk polar solvent. Compound 4 has zero emission in all solvents. The crystal structures of 3a, 3b, and 4 are reported, along with that of the parent 8-NH2-BODIPY (2). Compounds 2, 3a, and 3b exhibit trigonal planar N atoms which are coplanar with the BODIPY core; 4 exhibits a very significant distortion that breaks the planarity of the extended BODIPY π system due to the steric impact of the two ethyl groups, an observation that explains the lack of emission for 4.

Organometalloidal derivatives of the transition metals: IX. Synthesis and the crystal structure of (η5-C5H5)Fe(CO)2SiMe2-SiPh3

Abstract Reaction of (η5-C5H5)(CO)2FeNa with ClSiMe2-SiPh3 yields (η5-C5H5)-Fe(CO)2SiMe2-SiPh3. The crystal structure of the compound has been determined by X-ray diffraction. The SiSi bond distance is 2.374(1) A, which is longer by 0.018 A than that in Me3Si-SiPh3. This difference is in agreement with spectroscopic data, and is presumably due to the σ-donor property of the silyl group. The SiFe bond length is 2.346(1) A.

Cytotoxic effects of two organotin compounds and their mode of inflicting cell death on four mammalian cancer cells.

In this report, we have tested the cytotoxicity of two organotin (OT) compounds by flow cytometry on a panel of immortalized cancer cell lines of human and murine origin. Although the OT compounds exhibited varying levels of cytotoxicity, diphenylmethyltin chloride was more toxic than 1,4-bis (diphenylchlorostannyl)p-xylene on all cell lines tested. The OT compounds were found to be highly cytotoxic to lymphoma cell lines with lower toxicity toward the HeLa cervical cancer cell line. In order to discern the mechanism by which cell death was induced, additional experiments were conducted to monitor characteristic changes consistent with apoptosis and/or necrosis. Cell lines treated with the experimental compounds indicated that there was no consistent mode of cell death induction. However, both compounds induced apoptosis in the pro-B lymphocyte cell line, NFS-70. The work presented here also demonstrates that the two OT compounds possess selective cytotoxicity against distinct transformed cell lines.

The Photochemical Irradiation of R3SiH in the Presence of [(η5-C5H5)Fe(CO)2CH3] in DMF Leads to Disiloxanes not Disilanes†

The ability of DMF to react with the hydrogen formed in this dehydrocoupling process to produce Me3N was used to rationalize such interesting chemistry. In our hands, the irradiation of the tertiary silanes R3SiH reported in reference [2] (e.g. Ph2MeSiH (1), PhMe2SiH (2), Et3SiH (3)) in the presence of the catalyst [FpMe] in DMF solution results in the high-yield formation of the corresponding disiloxanes R3Si-O-SiR3 and no apparent formation of the disilane. In our experiments, 130 mg samples of the tertiary silanes (Gelest) were irradiated in dry DMF (Aldrich) with 5 mol% of the catalyst [FpMe] in sealed NMR tubes at a distance of 3 cm from a 400 W low-pressure mercury lamp. The reactions were monitored by Si NMR spectroscopy. The reactions with 1, 2, and 3 behaved similarly, with the disappearance of the resonance of the starting silane (d = 17.5 ppm (1) in 48 h; d = 17.2 ppm (2) in 1.5 h; d = 0.5 ppm (3) in 10 h) along with the appearance of a single resonance associated with the formation of the corresponding disiloxane R3SiOSiR3 (d = 9.1, 0.6, and 8.4 ppm for the reactions of 1, 2, and 3, respectively). No resonances associated with the corresponding disilanes were observed, for example (Ph2MeSi)2 at d = 22.6 ppm or (PhMe2Si)2 at d = 21.5 ppm. Figure 1 illustrates this clean process for silane 1. The GC–MS analysis of the product of this reaction also confirmed the formation of the disiloxane and the absence of

Ferrocenylenesilylene Polymers as Coatings for Tapered Optical-Fiber Gas Sensors

In this paper we report the use of ferrocenylenesilylene polymers as coatings for tapered optical-fiber sensors. The principle of operation of this device is based upon environmentally induced changes in the refractive index of the polymer layer which change the power transmitted through the tapered fiber. The results for two sensor arrays fabricated using the ferrocenylenesilylene polymer [(η5-C5H4)Fe(η5-C5H4)MePhSi]m and copolymer {[(η5-C5H4)Fe(η5-C5H4)SiPhMe]n[(η5-C5H4)Fe(η5-C5H4)Me2Si]m are presented. We also show that the sensitivity of this device is a function of the taper beat length.

Organometalloidal derivatives of the transition metals. III. σ- and π-silylallyl complexes

Abstract The reaction between 1- and 2-trialkylsilyl-3-chloroprop-1-ene and various metal complexes has led to the preparation of σ- and π-silylallyl complexes of Mn, Fe, Co, Ni, Mo, Pd and W. The general reactions employed involved the use of metal anions in a salt elimination reaction and oxidative addition reactions. The use of in situ silylallyl Grignard reagents with metal halides was also used to prepare silylallyl substituted compounds of Ge, Sn, and Ni. The chemical and physical properties of the new complexes are discussed, as are other attempted synthetic routes that led to metalloid or organic group transfer reactions.

Organometallic derivatives of the transition metals : VIII. Bonding and molecular motions in silyl transition metal complexes studied by 29Si NMR

Abstract Complexes of the general type [(η 5 -C 5 H 5 )Fe(L) 2 R], L  CO, PR′ 3 ; R  silyl, polysilyl, and silylmethyl, have been studied using 29 Si NMR. Chemical shift and nuclear Overhauser effect data have been obtained and related to the chemical bonding and molecular motion of the complexes. For the various dicarbonyl complexes sigma inductive effects by the iron substituent are noted, while upon phosphine substitution pi effects are observed with directly bonded silicon atoms present. From NOE η values segmental motion of the various chains may be noted, with the Fe iron atom effectively anchoring one end of the system.

Effect of a series of triorganotins on the immune function of human natural killer cells

Natural killer (NK) cells are our initial immune defense against viral infections and cancer development. They are able to destroy tumor and virally infected cells. Thus, agents that are able to interfere with their function increase the risk of cancer and/or infection. Organotins (OTs) have been shown to interfere with the tumor-destroying function of human NK cells. The purpose of the current study was to explore the relationship of a series of triorganotins, that differ in structure by only a single organic group, for their capacity to block NK tumor-cell destroying (lytic) function. Here we examine the series: trimethyltin (TMT), dimethylphenyltin (DMPT), methyldiphenyltin (MDPT), and triphenyltin (TPT). NK cells were exposed to TMT, DMPT, MDPT or TPT for 1, 24, 48h, or 6d. A 1h exposure to TMT, at concentrations as high as 20μM, had no effect on lytic function. However, concentrations as low as 2.5μM were able to decrease NK tumor-destroying function after 6d. A 1h exposure to DMPT had no effect on lytic function, however, after 6d there was an 80-90% decrease in lytic function at 1μM. Exposure to MDPT (as low as 2.5μM) decreased NK function at 1h, after 6d there was as much as a 90% decrease at concentrations as low as 100nM MDPT. TPT decreased lytic function in a manner similar to MDPT, however, it was more effective at 1h than MDPT. The effect of the triorganotins on the ability of NK cells to bind to targets was studied, to determine if this contributed to the loss of lytic function. The relative immunotoxic potential of this series of compounds is TPT≈MDPT>DMPT>TMT.