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Journal ArticleDOI

Phosphine complexes of the early metals and the lanthanoids

01 Jan 1991-Pure and Applied Chemistry (International Union of Pure and Applied Chemistry)-Vol. 63, Iss: 6, pp 845-850
TL;DR: The coordination chemistry of the mixed-donor tridentate ligand -N(SiMezCH2PR2)2 with the early transition metals of groups 3 and 4 and the lanthanide elements is presented in this paper.
Abstract: The coordination chemistry of the mixed-donor tridentate ligand -N(SiMezCH2PR2)2 with the early transition metals of groups 3 and 4 and the lanthanide elements will be presented. This ancillary ligand has allowed for the formation of phosphine complexes of these hard elements which has in turn induced new reactivity patterns for hydrocarbyl ligands. The stability and reactivity of metal complexes are a function of both the position of the metal in the periodic table and the nature of the ligands. While the former provides for diverse chemical reactivity, it is

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Book ChapterDOI
TL;DR: In this paper, a survey of the advances in heterocyclic chemistry is presented, including the structure, reactivity, and synthesis of specialized, natural, and synthetic biologically active heterocycles.
Abstract: Publisher Summary This chapter surveys the advances in heterocyclic chemistry. The structure, reactivity, and synthesis of specialized, natural, and synthetic biologically active heterocycles, such as nitrogen heterocycles and oxygen heterocycles, are described in the chapter. There are various kinds of heterocyclic rings: (1) three-membered rings, (2) four-membered rings, (3) five-membered rings, (4) six-membered rings, and (5) rings with more than six members. The three-membered rings consist of one heteroatom, two heteroatoms, and three heteroatoms; whereas, four-membered rings consist of one heteroatom and two heteroatoms. Five and six-membered rings comprise one heteroatom, two heteroatoms, three heteroatoms, and four heteroatoms. The heterocycle groups that contain unusual heteroatoms are— namely, group V element heterocycles, boron heterocycles, or selenium and tellurium heterocycles. The chemistry of individual classes of these heterocycles and their structure, stereochemistry, reactivity, and synthesis is also discussed in the chapter.

16 citations

Journal ArticleDOI
TL;DR: The new lithium amide LiN(SiMe( 2)CH(2)NMe(2), which exists as a dimer in the solid state wherein the two lithium ions are bridged by the two amido units with the amine arms of each unit bonded to opposite lithium centers in an overall pseudo D(2%) structure is presented.
Abstract: The new lithium amide LiN(SiMe2CH2NMe2)2 was prepared by reaction of NH3 with the corresponding silylamine Me2NSiMe2CH2NMe2 followed by addition of butyllithium. This lithium derivative exists as a dimer in the solid state wherein the two lithium ions are bridged by the two amido units with the amine arms of each unit bonded to opposite lithium centers in an overall pseudo D2 structure; however, in solution, a fluxional process serves to interconvert the enantiomeric forms of the dimer unit. The coordination chemistry of the lithium amide dimer has been investigated; reaction with a series of group 4 starting halides, MCl4, leads to the corresponding complexes MCl3[N(SiMe2CH2NMe2)2], where M = Ti, Zr, and Hf. The structures of these starting trihalides in solution and in the solid state are presented.

15 citations

Journal ArticleDOI
TL;DR: Compounds 3-5, 8-11 and 14 have been characterised by multi-element NMR spectroscopy; in addition, compounds 5, 11 and14 have been studied by X-ray crystallography.
Abstract: The secondary phosphines Ar(C6H4-2-CH2NMe2)PH [Ar = mes (3), Tripp (4)] may be isolated in good yields from reactions between Li(C6H4-2-CH2NMe2) and the respective dichlorophosphine, followed by reduction with LiAlH4 [mes = 2,4,6-Me3C6H2, Tripp = 2,4,6-Pri3C6H2]. Metalation of either 3 or 4 with BunLi gives the corresponding lithium compound; the lithium derivative of 3 was isolated as the separated ion pair complex [Li(12-crown-4)2][(mes)(C6H4-2-CH2NMe2)P].THF (5). The lithium complexes Ar(C6H4-2-CH2NMe2)PLi undergo metathesis reactions with either NaOBut or KOBut to give the heavier alkali metal phosphides {Ar(C6H4-2-CH2NMe2)P}M.1/2OEt2 [Ar = mes, M = Na (8), K (9); Ar = Tripp, M = K (10)]. Metathesis reactions between 9 and LaI3(THF)4 give only intractable products; in contrast, a metathesis reaction between 10 and LaI3(THF)4 yields the heteroleptic complex {(Tripp)(C6H4-2-CH2NMe2)P}2LaI (11). Compound 11 reacts cleanly with K{N(SiMe3)2} to give {(Tripp)(C6H4-2-CH2NMe2)P}2La{N(SiMe3)2} (14). Compounds 3-5, 8-11 and 14 have been characterised by multi-element NMR spectroscopy; in addition, compounds 5, 11 and 14 have been studied by X-ray crystallography.

13 citations

Journal ArticleDOI
TL;DR: The N-perfluoro-phenylated pyridyldiamine H2N2(PFP)N(py) has been prepared by a palladium-catalyzed coupling of hexafluorobenzene and the diamine using the palladacycle trans-di(μ-acetato)bis[o-(di-o-tolylphosphino)benzyl]palladium(II) as catalyst.
Abstract: The N-perfluoro-phenylated pyridyldiamine H2N2PFPNpy (1) has been prepared by a palladium-catalyzed coupling of hexafluorobenzene and the diamine (H2NCH2)2C(CH3)(2-C5H4N) using the palladacycle trans-di(μ-acetato)bis[o-(di-o-tolylphosphino)benzyl]palladium(II) as catalyst. Reactions of H2N2PFPNpy and Zr(NMe2)4 at room temperature or 90 °C led to the complexes [(NPFPN2TFAPNpy)ZrF(NMe2)] (2) and [(N2TFAPNpy)ZrF2] (3) in which one or two dimethylamido groups replaced one or two ortho fluorine atoms of the pentafluorophenyl groups in the ligand. Reaction of Me3SiX (X = Cl, I) with [(N2TFAPNpy)ZrF2] (3) resulted in the formation of mixed halogenated complexes [(N2TFAPNpy)ZrFI] (4) and [(N2TFAPNpy)ZrFCl] (5) in which the axially bound fluorido ligand is substituted. Reaction of [(N2TFAPNpy)ZrF2] (3) with LiNHNPh2 afforded the monohydrazido(1−) complex [(N2TFAPNpy)ZrF(NHNPh2)] (6) which was converted to the dimeric fluoro-potassium bridged hydrazinediido complex [Zr(N2TFAPNpy)FNNPh2K]2 (7) using KHMDS. The corre...

9 citations