- A practical method for the generation of organoarsenic nucleophiles towards the construction of a versatile arsenic library
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Nucleophilic arsenic reagents were prepared in situ from a nonvolatile cyclooligoarsine. As-As bond cleavage of the cyclooligoarsine readily proceeded with anion sources. Various kinds of organoarsenic compounds were easily constructed in high yields by selecting anion sources and electrophiles. In comparison with conventional methods of As-C bond formation, a wide variety of organoarsenic compounds were safely and easily synthesized by using this method.
- Tanaka, Susumu,Imoto, Hiroaki,Kato, Takuji,Naka, Kensuke
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supporting information
p. 7937 - 7940
(2016/06/09)
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- Heat of reaction of (norbornadiene)molybdenum tetracarbonyl with monodentate and bidentate ligands. Solution thermochemical study of ligand substitution in the complexes cis-L2Mo(CO)4
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The enthalpy of reaction of (NBD)Mo(CO)4 (NBD = norbornadiene) with a number of monodentate and bidentate ligands forming cis-L2Mo(CO)4 has been measured at 30°C in THF solution. The heats of reaction span a range of 33 kcal/mol. The order of stability for monodentate ligands is PCl3 6H5)3 6H5)3 3 6H5)3 6H5)2(CH3) 6H5)(CH3)2 3)3 3 6H11)NC 3 3. The series of chelating bidentate phosphines R2P-(CH2)nPR2 (n = 1-4, R = C6H5; n = 1, 2, R = CH3) and several related ligands were investigated. The chelating ring systems in the metallacycles show strain energies of about 8 kcal/mol for four-membered rings. The mixed ligand (C6H5)2PCH2CH2-As(C 6H5)2 shows a heat of binding midway between the heats of binding of (C6H5)2PCH2CH2P(C 6H5)2 and (C6H5)2AsCH2C-H2As(C 6H5)2, implying group additivity in this system. The complex (phen)Mo(CO)4 is some 5 kcal/mol more stable than (bpy)Mo(CO)4, presumably due to conformational effects in the free ligand. The ligand 1,5-cyclooctadiene forms a complex 2 kcal/mol less stable than that of norbornadiene. The influences of steric and electronic factors in determining the Mo-L bond strength are discussed.
- Mukerjee, Shakti L.,Nolan, Steven P.,Hoff, Carl D.,Lopez De La Vega, Ramon
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- Steric and electronic control of the Arbuzov reaction in transition-metal halides: A 1H and 31P NMR study of the reaction of [CpCo(L L)X]+ complexes (L L = N, P, as chelate ligands; X- = Cl-, Br-, I-, CN-) with P(OCH3)3
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Synthesis of a series of complexes, [CpCo(L L)X]+ (L L = N, P, As chelate ligands; X- = Cl-, Br-, I-, CN-), was undertaken with the goal of characterizing the Michaelis-Arbuzov reaction between these complexes and P(OCH3)3. 1H and 31P NMR results provide support for the previously postulated two-step mechanism involving an initial equilibrium reaction [CpCo(L L)X]+ + P(OCH3)3 ? {CpCo(L L)[P(OCH3)3]}2+ + X- followed by alkylation of X- to produce an organometal-phosphonate complex, {CpCo(L L)[P(OCH3)3]}2+ + X- → {CpCo(L L)[P(O)(OCH3)2]}+ + CH3X. Several of the intermediate phosphite dications were synthesized and characterized. They enable the above reactions to be qualitatively separated. The initial reaction was quenched by sterically bulky chelate ligands. The rate of the overall reaction parallels the electron donor power of the attacking nucleophile (CN- > I- > Br- > Cl-) and also depends on the donor atoms of L L (N > P). Chelate dissociation occurs when L L = As. The results for [CpCo(L L)X]+ and other transition metal-halide complexes are discussed in terms of why the Arbuzov reaction takes place in some of these complexes but not with others.
- Landon, Shayne J.,Brill, Thomas B.
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p. 1266 - 1271
(2008/10/08)
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- New Reagents, XIX. Coupling of (Lithiomethyl)diphenylarsane Oxide to 1,2-Bis(diphenylarsinyl)ethane, its Reduction and Fragmentation
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(Lithiomethyl)diphenylarsane oxide (1) reacts with CuCl2 to give 1,2-bis(diphenylarsinyl)ethane (2a, 64percent) which is reduced by NaBH4 or LiAlH4 to the monoxide (3a, 88percent) or diarsane (4, ca. 100percent), respectively.The monolithiation products of 2a and 3a in each case decompose at low temperature affording diphenylvinylarsane oxide (6; 76 or 85percent, respectively).
- Kauffmann, Thomas,Joussen, Rolf
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p. 654 - 658
(2007/10/02)
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