PubMed Health⌕ Search

Biomedical subjects

M Thornton-Pett

Publications and source records attributed to M Thornton-Pett.

18 recordsLinked to original sources
PubMed2001

Two complexes of CuBr(2) with 5-tert-butylpyrazole.

trans-Dibromobis(5-tert-butylpyrazole-N(2))copper(II), trans-[CuBr(2)(Hpz(tBu))(2)] (Hpz(tBu) is 5-tert-butylpyrazole, C(7)H(12)N(2)), exhibits a distorted square-planar geometry with a significant tetrahedral twist, while trans-dibromotetrakis(5-tert-butylpyrazole-N(2))copper(II), trans-[CuBr(2)(Hpz(tBu))(4)], adopts a distorted octahedral geometry across a crystallographic inversion centre. Both compounds exhibit intramolecular N--H...Br hydrogen-bonding interactions.

Journal Article↗
PubMed2001

Bis[tris(3-cyclohexylpyrazol-1-yl)-hydridoborato]copper(II) dichloromethane disolvate.

The title compound, [Cu(C27H40BN6)2]*2CH2Cl2, contains a four-coordinate Cu(II) ion lying on a crystallographic inversion centre, giving rise to a near-regular square-planar stereochemistry. There is an axial contact of 2.71 A between the Cu ion and ligand B-H group, although this is unlikely to correspond to a significant 'agostic' interaction.

Journal Article↗
PubMed2001

Ten-vertex rhodadithiaborane chemistry:.

Neutral 8-(5-iodo-n-pentyl)-3-(eta(5)-pentamethylcyclopentadienyl)-arachno-3-rhoda-7,8-dithiaundecaborane, [Rh(C(5)H(19)B(8)IS(2))(C(10)H(15))], obtained from the [arachno-7,8-S(2)B(9)H(10)](-) anion by treatment with I(CH(2))(5)I followed by [Rh(C(5)Me(5))Cl(2)](2) and N,N,N',N'-tetramethyl-1,8-diaminonaphthalene, has the 11-vertex cluster geometry of [arachno-7,8-S(2)B(9)H(10)](-), but with an [Rh(C(5)Me(5))] unit in the 3-position instead of a [BH] unit, and with a -(CH(2))(5)I chain attached exo to an S atom.

Journal Article↗
PubMed2001

N-monofunctionalized 1,4,7-triazacyclononane macrocycles as building blocks in inorganic crystal engineering.

The syntheses of N-(3-prop-1-ene)-1,4,7-triazacyclononane molybdenum tricarbonyl (2), N-(4-but-1-ene)-1,4,7-triazacyclononane molybdenum tricarbonyl (3), N-(3-prop-1-ene)-1,4,7-triazacyclononane molybdenum trioxide (5), N-(4-but-1-ene)-1,4,7-triazacyclononane molybdenum trioxide (6), N-(hydroxyethyl)-1,4,7-triazacyclononane molybdenum trioxide (7), and N-(2-methylpyridyl)-1,4,7-triazacyclononane molybdenum trioxide (8) have been achieved. The objective of this work is to systematically vary the functionality of the pendant group in order to create different crystal packing in the solid state. This is evidenced in comparing the structures of 1,4,7-triazacyclononane molybdenum trioxide (4) and 5-8, which were determined using X-ray crystallography. The synthesis and characterization of the new ligand N-(2-methylpyridyl)-1,4,7-triazacyclononane (L5) is reported.

Journal Article↗
PubMed2001

Synthesis, structures, and reactivity of weakly coordinating anions with delocalized borate structure: the assessment of anion effects in metallocene polymerization catalysts.

The formation of adducts of tris(pentafluorophenyl)borane with strongly coordinating anions such as CN(-) and [M(CN)(4)](2)(-) (M = Ni, Pd) is a synthetically facile route to the bulky, very weakly coordinating anions [CN[B(C(6)F(5))(3)](2)](-) and [M[CNB(C(6)F(5))(3)](4)](2-) which are isolated as stable NHMe(2)Ph(+) and CPh(3)(+) salts. The crystal structures of [CPh(3)][CN[B(C(6)F(5))(3)](2)] (1), [CPh(3)][ClB(C(6)F(5))(3)] (2), [NHMe(2)Ph](2)[Ni[CNB(C(6)F(5))(3)](4)].2Me(2)CO (4b.2Me(2)CO), [CPh(3)](2)[Ni[CNB(C(6)F(5))(3)](4)].2CH(2)Cl(2) (4c.2CH(2)Cl(2)), and [CPh(3)](2)[Pd[CNB(C(6)F(5))(3)](4)].2CH(2)Cl(2) (5c.2CH(2)Cl(2)) are reported. The CN stretching frequencies in 4 and 5 are shifted by approximately 110 cm(-1) to higher wavenumbers compared to the parent tetracyano complexes in aqueous solution, although the M-C and C-N distances show no significant change on B(C(6)F(5))(3) coordination. Zirconocene dimethyl complexes L(2)ZrMe(2) [L(2) = Cp(2), SBI = rac-Me(2)Si(Ind)(2)] react with 1, 4c or 5c in benzene solution at 20 degrees C to give the salts of binuclear methyl-bridged cations, [(L(2)ZrMe)(2)(mu-Me)][CN[B(C(6)F(5))(3)](2)] and [(L(2)ZrMe)(2)(mu-Me)](2)[M[CNB(C(6)F(5))(3)](4)]. The reactivity of these species in solution was studied in comparison with the known [[(SBI)ZrMe](2)(mu-Me)][B(C(6)F(5))(4)]. While the latter reacts with excess [CPh(3)][B(C(6)F(5))(4)] in benzene to give the mononuclear ion pair [(SBI)ZrMe(+).B(C(6)F(5))(4)(-)] in a pseudo-first-order reaction, k = 3 x 10(-4) s(-1), [(L(2)ZrMe)(2)(mu-Me)][CN[B(C(6)F(5))(3)](2)] reacts to give a mixture of L(2)ZrMe(mu-Me)B(C(6)F(5))(3) and L(2)ZrMe(mu-NC)B(C(6)F(5))(3). Recrystallization of [Cp' '(2)Zr(mu-Me)(2)AlMe(2)][CN[B(C(6)F(5))(3)](2)] affords Cp' '(2)ZrMe(mu-NC)B(C(6)F(5))(3) 6, the X-ray structure of which is reported. The stability of [(L(2)ZrMe)(2)(mu-Me)](+)X(-) decreases in the order X = [B(C(6)F(5))(4)] > [M[CNB(C(6)F(5))(3)](4)] > [CN[B(C(6)F(5))(3)](2)] and increases strongly with the steric bulk of L(2) = Cp(2) << SBI. Activation of (SBI)ZrMe(2) by 1 in the presence of AlBu(i)(3) gives extremely active ethene polymerization catalysts. Polymerization studies at 1-7 bar monomer pressure suggest that these, and by implication most other highly active ethene polymerization catalysts, are strongly mass-transport limited. By contrast, monitoring propene polymerization activities with the systems (SBI)ZrMe(2)/1/AlBu(i)(3) and CGCTiMe(2)/1/AlBu(i)(3) at 20 degrees C as a function of catalyst concentration demonstrates that in these cases mass-transport limitation is absent up to [metal] approximately 2 x 10(-5) mol L(-1). Propene polymerization activities decrease in the order [CN[B(C(6)F(5))(3)](2)](-) > [B(C(6)F(5))(4)](-) > [M[CNB(C(6)F(5))(3)](4)](2-) >> [MeB(C(6)F(5))(3)](-), with differences in activation barriers relative to [CN[B(C(6)F(5))(3)](2)](-) of DeltaDeltaG = 1.1 (B(C(6)F(5))(4)(-)), 4.1 (Ni[CNB(C(6)F(5))(3)](4)(2-)) and 10.7-12.8 kJ mol(-)(1) (MeB(C(6)F(5))(3)(-)). The data suggest that even in the case of very bulky anions with delocalized negative charge the displacement of the anion by the monomer must be involved in the rate-limiting step.

Journal Article↗
PubMed2001

Two iridanonaborane compounds.

Two iridanonaborane compounds, 4-carbonyl-5,6:8,9-bis-muH-4-hydrido-4-bis(trimethylphosphine)-4-irida-arachno-nonaborane(12), [IrH(B8H12)(C3H9P)2(CO)], (Ia), and 2-carbonyl-2,5:6,9:8,9-tri-muH-4-chloro-2-bis(trimethylphosphine)-2-irida-nido-nonaborane(11), [Ir(B8H10Cl)(C3H9P)2(CO)], (II), are described. Compound (II) shows evidence of effective chlorine-substituent migration during its formation.

Journal Article↗
PubMed2001

[Mu-6,9-Cl-8-(OMe)-6,9-eta5-C5Me5)2-arachno-6,9,5-rh2SB7H7].

The title compound, mu-6,9-chloro-8-methoxy-6,9-bis(eta5-pentamethylcyclopentadienyl)-6,9-dirhoda-5-thia-arachno-decaborane(7), [Rh2(CH10B7OS)(C10H15)2Cl], has a single Cl atom bridging the two remote rhodium 'prow' vertices of an arachno ten-vertex dirhodathiadecaborane cluster, with Rh-Cl distances of 2.3475 (11) and 2.3536 (11) A, and an Rh-Cl-Rh angle of 106.82 (4) degrees.

Journal Article↗
PubMed2001

1-(Dibromomethyl)-4-methoxy-2-methylbenzene.

The title compound, C(9)H(10)Br(2)O, is a major product of the radical bromination of 4-methoxy-1,2-dimethylbenzene. Each Br atom is involved in a close contact with the O atom of a neighbouring molecule, forming a geometry that is suggestive of weak intermolecular O--> Br charge-transfer interactions.

Journal Article↗
PubMed2000

4'-Vinyl-2,2':6',2"-terpyridine

The title compound, C(17)H(13)N(3), is a versatile precursor for polymeric terpyridine derivatives and their metal complexes. The molecule has transoid and near-coplanar pyridine rings. However, the vinyl group is forced out of the plane of the terpyridyl moiety by a close H.H contact.

Journal Article↗
PubMed2000

[1,1,2,2-]

The title compound, 1,1,2,2-tetracarbonyl-1,2-&mgr;-carbonyl-4, 11-dimethylsulfido-closo-1,2-dicobaltadodecaborane, [Co(2)(C(4)H(20)B(10)S(2))(CO)(5)], has a closo 12-vertex 1, 2-Co(2)B(10)H(8) structure with SMe(2) ligands at the exo-4- and 11-positions. The cluster displays close structural similarities to the SEt(2) analogue.

Journal Article↗
PubMed2000

Bis2,6-bis

The title compound, [Zn(C(29)H(29)N(5))(2)](ClO(4))(2).2CH(3)NO(2), contains a Zn(II) ion showing only small deviations from local D(2d) symmetry. The lower rhombicity exhibited by this complex compared with that of its Cu(II) congener suggests that the highly rhombic stereochemistry exhibited by the latter is largely imposed by the stereoelectronic preferences of the Cu(II) ion.

Journal Article↗
PubMed2000

Bis

Explore the source record for details and available documents.

Journal Article↗