1,2,3-triphenyiphosphirene Derivatives Of The Iridium Carbonyl Clusters [hir4(co)9l(μ-pph2)] (l = Co, Pph3) Resulting From Substitution, Insertion And Hydrometallation Processes 1

1,2,3-Triphenylphosphirene reacts with [HIr4(CO)10(μ-PPh2)] 1, at room temperature, to afford [Ir4(CO)8(μ3-μ 2PhPCPh=CPh)(μ-PhPCPh=CHPh)(μ-PPh2)] 2 which contains the phosphametallacycle (μ3-η2-PhPCPh=CPh) and the phosphidoalkenyl (μ-PhPCPh=CHPh) ligands arising from insertion and hydrometallation processes respectively. In contrast, the PPh3 derivative of 1, [HIr4(CO)9(PPh3)(μ-PPh2)] 3, reacts selectively at room temperature with the phosphirene to give only CO substitution products, [HIr4(CO)9-n(PPh3)(η 1-PhPCPh=CPh)n(μ-PPh2)] (n=1,4 and 2, 5) which are the first carbonyl cluster compounds containing intact η1-ligated phosphirene rings. High yield conversion of compound 4 into the phosphametallacycle species [HIr4(CO)7(PPh3)(μ3-η 2-PhPCPh=CPh)(μ-PPh2)] 6 is achieved under mild thermolytic conditions. An insight into the mechanism of formation of 2 was given by the reaction of the phosphirene ring with the anion [Ir4(CO)10(μ-PPh2)]- 1a derived from 1, followed by protonation, which gave [HIr4(CO)8(μ3-η 2-PhPCPh=CPh)(μ-PPh2)] 7, which is analogous to 6 with a CO ligand replacing PPh3. Quantitative conversion of the hydride phosphametallacycle 7 into the labile phosphidoalkenyl cluster [Ir4(CO)n(μ-PhPCPh=CHPh)(μ-PPh2)] 8 is easily achieved in the presence of CO (1 atm, RT, 2 h), as a result of the reductive elimination of a C-H group. Compound 8 undergoes facile CO dissociation and co-ordination of the phosphidoalkenyl C=C bond to the metal centre to produce [Ir4(CO)9(μ3-η 3-PhPCPh=CHPh)(μ-PPh2)] 9. The molecular structures of compounds 2,4,6 and 9 were established by X-ray diffraction studies and the structures of all compounds in solution were investigated by a combination of 1H and 31P{1H} NMR studies. © The Royal Society of Chemistry 2000.1525272536Mathey, F., (1990) Chem. Rev., 90, p. 997Mathey, F., Regitz In, M., (1996) Comprehensive Heterocyclic Chemistry II, , Pergamon, OxfordDillon, K.B., Mathey, F., Nixon, J.F., (1998) Phosphorus: the Carbon Copy, , John Wiley, ChichesterMercier, F., Deschamps, B., Mathey, F., (1989) J. Am. Chem. Soc, 111, p. 9098Marinetti, A., Mathey, F., Fischer, J., Mitschier, A., (1982) J. Am. Chem. Soc., 104, p. 4484Marinetti, A., Mathey, F., (1985) J. Am. Chem. Soc., 107, p. 4700Al-Juaid, S.S., Carmichael, D., Hitchcock, P.B., Lochschmidt, S., Marinetti, A., Mathey, F., Nixon, J.F., (1988) J. Client. Soc., Chem. Commun., p. 1156Marinetti, A., Mathey, F., (1987) Tetrahedron Lett., 28, p. 5021Espinosa Ferao, A., Deschamps, B., Mathey, F., (1993) Bull. Soc. Chim. Fr., 130, p. 695Marinetti, A., Fischer, J., Mathey, F., (1985) J. Am. Chem. Soc., 107, p. 5001Carmichael, D., Hitchcock, P.B., Nixon, J.F., Mathey, F., Pidcock, A., (1986) J. Chem. Soc., Chem. Commun., p. 762Al-Juaid, S.S., Carmichael, D., Hitchcock, P.B., Marinetti, A., Mathey, F., Nixon, J.F., (1991) J. Client. Soc., Dalton Trans., p. 905Ajulu, F.A., Carmichael, D., Hitchcock, P.B., Mathey, F., Meidine, M.F., Nixon, J.F., Ricard, L., Riley, M.L., (1992) J. Chem. Soc., Client. Commun., p. 750Carmichael, D., Hitchcock, P.B., Mathey, F., Nixon, J.F., Ricard, L., (1993) J. Client. Soc., Dalton Trans., p. 1811Arce, A.J., De Sanctis, Y., Machado, R., Campparelli, M.V., Mansur, J., Deeming, A.J., (1995) Organometallics, 14, p. 3592Livotto, F.S., Raithby, P.R., Vargas, M.D., (1993) J. Chem. Soc., Dalton Trans., p. 1797Araujo, M.H., (1995), Ph.D. Thesis, Universidade Estadual de Campinas, BrazilVargas, M.D., Pereira, R.M.S., Braga, D., Grepioni, F., (1993) J. Chem. Soc., Chem. Commun., p. 1008(1999) J. Bra:. Chem. Soc., 10, p. 35Benvenutti, M.H.A., Vargas, M.D., Braga, D., Grepioni, F., Parisini, E., Mann, B.E., (1993) Organomelallics, 12, p. 2955Benvenutti, M.H.A., Vargas, M.D., Braga, D., Grepioni, F., Mann, B.E., Naylor, S., (1993) Organomelallics, 12, p. 2947Benvenutti, M.H.A., Hitchcock, P.B., Nixon, J.F., Vargas, M.D., (1994) J. Chem. Soc., Chem. Commun., p. 1869Araujo, M.H., Hitchcock, P.B., Nixon, J.F., Vargas, M.D., (1998) J. Bra:. Chem. Soc., 9, p. 563Carty, A.J., Mac Laughlin, S.A., Nucciaroni, D., (1987) Phosphorus 31-NMR Spectroscopy in Stereochemical Analysis of Organic Compounds and Metal Complexes, , ed. J. G. Verkade and L. D. Quin, VCH, Weinheim, ch. 16Browning, J., Dixon, K.R., Meanwell, N.J., (1993) Inorg. Ciim. Acta, 213, p. 171Berry, D.E., Browning, J., Dehghan, K., Dixon, K.R., Meanwell, N.J., Phillips, A., (1991) Inorg. Client., 30, p. 396Ros, R., Scrivanti, A., Albano, V.G., Braga, D., Garlaschelli, L., (1986) J. Chem. 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Oxidative Addition Reactions Of I2 With [hir4(co)10-n(pph3)n(μ-pph 2)] (n = 1 And 2) And Crystal And Molecular Structure Of [hir4(μ-i)2(co)7(pph3)(μ- Pph2)]

The reactions of the cluster compounds [HIr4(CO)10-n(PPh3)n(μ-PPh 2)] [n = 0, (1); 1, (2) and 2, (3)] with I2 have been investigated. Compound 1 does not react, however, the presence of PPh3 in place of CO ligand(s) activates the cluster. Both compounds 2 and 3 react with I2 under mild conditions to give [HIr4(μ-I)2(CO)7(PPh3)(μ- PPh2)] (4), as the result of oxidative addition of I2 and dissociation of two CO ligands, or one CO and one PPh3 ligands, respectively. The molecular structure of 4, determined by an X-ray diffraction study, exhibits a butterfly arrangement of iridium atoms with the wings spanned by a μ-PPh2 ligand, the hinge bridged by a μ-H ligand, two hinge to wing tip edges bridged by iodine atoms and all metal atoms bearing two CO ligands, with the exception of one of the hinge atoms that contains a CO and a PPh3 ligands. This cluster exhibits the shortest average Ir-Ir bond length [2.698(2) Å] observed so far for a derivative of 1 and this is in accord with the relatively high average oxidation state of its metal atoms (+1) for a carbonyl cluster compound.135682686Livotto, F.S., Raithby, P.R., Vargas, M.D., (1993) J. Chem. Soc., Dalton Trans., p. 1797Araujo, M.H., (1995), Ph.D. Thesis, Universidade Estadual de Campinas, BrazilVargas, M.D., Pereira, R.M.S., Braga, D., Grepioni, F., (1993) J. Chem. Soc., Chem. Commun., p. 1008Vargas, M.D., Pereira, R.M.S., Braga, D., Grepioni, F., (1999) J. Braz. Chem. Soc., 10, p. 35Benvenutti, M.H.A., Vargas, M.D., Braga, D., Grepioni, F., Parisini, E., Mann, B.E., (1993) Organometallics, 12, p. 2955Benvenutti, M.H.A., Vargas, M.D., Braga, D., Grepioni, F., Mann, B.E., Naylor, S., (1993) Organometallics, 12, p. 2947Benvenutti, M.H.A., Hitchcock, P.B., Nixon, J.F., Vargas, M.D., (1994) J. Chem. Soc., Chem. Commun., p. 1869Araujo, M.H., Hitchcock, P.B., Nixon, J.F., Vargas, M.D., (1998) J. Braz. Chem. Soc., 9, p. 563Hitchcock, P.B., Nixon, J.F., Vargas, M.D., Ziglio, C.M., (2000) J. Chem. Soc., Dalton Trans., p. 2527Collman, J.P., Hegedus, L.S., Norton, J.R., Finke, R.G., (1987) Principles and Applications of Organometallic Chemistry, 2nd Ed., , University Science Books: Mill Valley, CALivotto, F.S., Raithby, P.R., Vargas, M.D., (1993) J. Chem. Soc., Dalton Trans., p. 1797Sheldrick, G.M., (1997) SHELXL97 - Single Crystal Structure Determination Software, , University of Göttingen, GermanyKeller, E., (1999) SCHAKAL99 - Graphical Representation of Molecular Models, , University of Freiburg, GermanyCarty, A.J., MacLaughlin, S.A., Nucciaroni, D., (1987) Phosphorus 31-NMR Spectroscopy in Stereochemical Analysis, , Verkade, J. G.Quin, L. D., eds, VCH: Deerfield Beach, FL, ch 16Riera, V., Ruiz, M.A., Villafañe, F., Bois, C., Jeannin, Y., (1993) Organometallics, 12, p. 124Johnson, B.F.G., Lewis, J., Nicholls, J.N., Puga, J., Whitmire, K.H., (1983) J. Chem. Soc., Dalton Trans., p. 787Johnson, B.F.G., Lewis, J., Nelson, W.J.H., Nicholls, J.N., Vargas, M.D., (1984) J. Chem. Soc., Dalton Trans., p. 1809Mingos, D.M.P., Wales, D.J., (1990) Introduction to Cluster Chemistry, , Prentice Hall: New JerseyVargas, M.D., Nicholls, J.N., (1986) Adv. Inorg. Radiochem., 30, p. 123Sanati, H., Becalska, A., Ma, A.K., Pomeroy, R.K., (1990) J. Chem. Soc., Chem. Commun., p. 197Hui, J.W.S., Wong, W.T., (1990) Organometallics, 9, p. 132

Potencial de extratos de resíduos vegetais na mobilização do calcário no solo por método biológico Plant residue extracts potential for lime mobility in the soil using a biological method

O calcário aplicado na superfície do solo apresenta baixa eficiência na correção da acidez subsuperficial. A eficiência pode ser melhorada através de compostos orgânicos hidrossolúveis liberados pelos resíduos vegetais. Foi avaliado um método biológico para testar a capacidade de extratos vegetais na mobilização do calcário no solo. O método consiste das seguintes etapas: coleta e preparo do material vegetal; extração dos compostos orgânicos hidrossolúveis; preparo da coluna de solo; aplicação do calcário na superfície do solo; aplicação do extrato vegetal; irrigação com água destilada; teste biológico com a planta indicadora de trigo cv. Anahuac e avaliação do crescimento radicular. A calagem sem resíduo vegetal aumentou o pH e o teor de Ca e diminuiu o teor de Al apenas na camada 0 a 5 cm de profundidade. A calagem com resíduos de aveia preta e nabo forrageiro aumentou o pH e o teor de Ca e diminuiu o teor de Al na camada de 0 a 20 cm de profundidade. Por outro lado, a calagem com resíduos de trigo não afetou a mobilidade do calcário no solo. O crescimento das raízes acompanhou os efeitos na química do solo: calagem sem resíduo e calagem com resíduo de trigo apresentaram crescimento das raízes até 10 cm de profundidade enquanto a calagem com resíduos de aveia e nabo favoreceu o crescimento das raízes até 20 cm de profundidade. O teste biológico foi adequado para avaliar a eficiência de resíduos vegetais na mobilização do calcário no solo.<br>Soil surface applied lime shows low efficiency in alleviating subsoil acidity. Lime efficiency is increased through water-soluble organic compounds released from plant residues. A biological test was evaluated to verify the capacity of plant extracts on lime mobility in the soil. The test presents the following steps: plant material preparation; extraction of water soluble organic compounds; soil column preparation; soil surface lime addition; plant extract addition; irrigation with distillated water; biological test with an indicator plant (wheat, cultivar Anahuac); and root growth evaluation. Surface applied lime without plant residue increased pH and Ca, and decreased Al in the top 5 cm of soil. Lime with black oats and oil seed radish extracts increased pH and Ca and decreased Al up to the 20 cm soil depth. Wheat residue had no effect on lime mobility. Indicator root growth followed the effect of treatments on soil chemical composition: lime without plant residue enhanced root growth in the top 10 cm depth and lime with black oats and oil seed radish enhanced root growth up to the 20 cm depth. The biological test was efficient to evaluate the ability of plant residues in relation to lime mobility in the soil