title: Reactivity, structure and electrospray mass spectrometry of pentafluoro- and pentachloro-phenoxy-substituted cyclotriphosphazenes

authors: Depree, Craig V.

subjects: Pentafluoro-cyclotriphosphazene

abstract: The reaction of N3P3Cl6 with the sodium salts of pentachloro- and pentafluorophenol, has been investigated. In contrast to the non-geminal substitution typified by other RO− nucleophiles, the regiochemistry of the reaction of C6X5O− (X=Cl and F) with N3P3Cl6 is dominated by geminal substitution. The reaction of C6Cl5O− with N3P3Cl6 in refluxing tetrahydrofuran yielded gem-N3P3Cl2(OC6Cl5)4 (1) as the major product. The fully substituted derivative N3P3(OC6Cl5)6 (2) was attained in low yield from reaction in refluxing diglyme. In contrast, the reaction of C6F5O− with N3P3Cl6 in refluxing tetrahydrofuran yielded the fully substituted product N3P3(OC6F5)6 (3) after approximately 4 h. 31P NMR spectral results suggest the C6F5O− ion may be attacking in a 'random' fashion at low degrees of substitution, which is largely replaced by an electronic geminal-directing effect at tetrasubstitution. Single crystal X-ray crystallographic analyses have been carried out on compounds 1 and 3. Electrospray mass spectrometry has been evaluated as a general technique for characterizing cyclotriphosphazenes, N3P3R6. If R=OEt or OPh, good positive ion spectra are observed but, in contrast, if R is more strongly electron withdrawing (Cl, C6Cl5O or C6F5O) negative ion spectra are obtained.

text: Reactivity, structure and electrospray mass spectrometry of pentafluoro- and pentachloro-phenoxy-substituted cyclotriphosphazenes The reaction of N3P3Cl6 with the sodium salts of pentachloro- and pentafluorophenol, has been investigated. In contrast to the non-geminal substitution typified by other RO− nucleophiles, the regiochemistry of the reaction of C6X5O− (X=Cl and F) with N3P3Cl6 is dominated by geminal substitution. The reaction of C6Cl5O− with N3P3Cl6 in refluxing tetrahydrofuran yielded gem-N3P3Cl2(OC6Cl5)4 (1) as the major product. The fully substituted derivative N3P3(OC6Cl5)6 (2) was attained in low yield from reaction in refluxing diglyme. In contrast, the reaction of C6F5O− with N3P3Cl6 in refluxing tetrahydrofuran yielded the fully substituted product N3P3(OC6F5)6 (3) after approximately 4 h. 31P NMR spectral results suggest the C6F5O− ion may be attacking in a 'random' fashion at low degrees of substitution, which is largely replaced by an electronic geminal-directing effect at tetrasubstitution. Single crystal X-ray crystallographic analyses have been carried out on compounds 1 and 3. Electrospray mass spectrometry has been evaluated as a general technique for characterizing cyclotriphosphazenes, N3P3R6. If R=OEt or OPh, good positive ion spectra are observed but, in contrast, if R is more strongly electron withdrawing (Cl, C6Cl5O or C6F5O) negative ion spectra are obtained.

year: 2000-09-01

title: Cyclorhenated compounds derived from 1,4-diaryl-1-azabutadienes: preparation, structures and reactions

authors: Asamizu, Toshie

subjects: Cyclometallation

abstract: PhCH₂Re(CO)₅ reacted with 1,4-diaryl-1-azabutadienes to give cyclometallated (η²-(C,N)-azabutadiene)Re(CO)₄ (4) together with the substituted derivatives (η¹-(N)-azabutadiene)(η²-(C,N)-azabutadiene)Re(CO)₃ (6 and 7) The substituted product was shown by NMR and X-ray crystal structure analysis to be an inseparable mixture of isomers differing in the conformation of the η¹-ligand about the N C bond—trans for (6) and cis for (7). Reaction of the mixture of 6 and 7 from 1,4-diphenyl-1-azabutadiene with phenyl acetylene gave η⁵-(1,2,4-triphenyl-1-aza-cyclohexadienyl)Re(CO)₃.

text: Cyclorhenated compounds derived from 1,4-diaryl-1-azabutadienes: preparation, structures and reactions PhCH₂Re(CO)₅ reacted with 1,4-diaryl-1-azabutadienes to give cyclometallated (η²-(C,N)-azabutadiene)Re(CO)₄ (4) together with the substituted derivatives (η¹-(N)-azabutadiene)(η²-(C,N)-azabutadiene)Re(CO)₃ (6 and 7) The substituted product was shown by NMR and X-ray crystal structure analysis to be an inseparable mixture of isomers differing in the conformation of the η¹-ligand about the N C bond—trans for (6) and cis for (7). Reaction of the mixture of 6 and 7 from 1,4-diphenyl-1-azabutadiene with phenyl acetylene gave η⁵-(1,2,4-triphenyl-1-aza-cyclohexadienyl)Re(CO)₃.

year: 2010

title: 'Closing the Gaps': From postcolonialism to Kaupapa Māori and beyond.

authors: Mahuika, Nepia

subjects: New Zealand

abstract: The article discusses New Zealand history, particularly examining Māori theories and interpretations of history. It considers postcolonial theory and Kaupapa Māori theory. The author comments on the government policy of "closing the gaps," referring to efforts to improve the conditions of underachieving New Zealand groups. He also reflects on Mātauranga, a Māori concept concerning knowledge. The history and oral tradition of the people of the Māori iwi, or social unit, of Ngati Porou is also discussed.

text: 'Closing the Gaps': From postcolonialism to Kaupapa Māori and beyond. The article discusses New Zealand history, particularly examining Māori theories and interpretations of history. It considers postcolonial theory and Kaupapa Māori theory. The author comments on the government policy of "closing the gaps," referring to efforts to improve the conditions of underachieving New Zealand groups. He also reflects on Mātauranga, a Māori concept concerning knowledge. The history and oral tradition of the people of the Māori iwi, or social unit, of Ngati Porou is also discussed.

year: 2011