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Titolo:
The chemistry of transition metal complexes containing a phosphenium ligand
Autore:
Nakazawa, H;
Indirizzi:
Hiroshima Univ, Grad Sch Sci, Dept Chem, Higashihiroshima 7398526, Japan Hiroshima Univ Higashihiroshima Japan 7398526 hihiroshima 7398526, Japan
Titolo Testata:
JOURNAL OF ORGANOMETALLIC CHEMISTRY
fascicolo: 1-2, volume: 611, anno: 2000,
pagine: 349 - 363
SICI:
0022-328X(20001006)611:1-2<349:TCOTMC>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
X-RAY CRYSTAL; ELECTROPHILIC HALOGEN EXCHANGE; NUCLEAR MAGNETIC-RESONANCE; GROUP-14 ELEMENT LIGAND; MIGRATORY INSERTION; BORON TRIHALIDES; C BOND; PERFLUOROALKYL COMPLEXES; MOLYBDENUM COMPLEXES; MOLECULAR-STRUCTURES;
Keywords:
cationic phosphenium complexes; OR- abstraction; migratory insertion; pi-back donation; double bond; rotational barrier;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
88
Recensione:
Indirizzi per estratti:
Indirizzo: Nakazawa, H Hiroshima Univ, Grad Sch Sci, Dept Chem, Higashihiroshima 7398526, Japan Hiroshima Univ Higashihiroshima Japan 7398526 7398526, Japan
Citazione:
H. Nakazawa, "The chemistry of transition metal complexes containing a phosphenium ligand", J ORGMET CH, 611(1-2), 2000, pp. 349-363

Abstract

A molybdenum complex containing diamino-substituted phosphite, fac-[(bpy)(CO)(3)Mo{PNN(OMe)}] (PNN stands for PN(Me)CH2CH2NMe) reacts with a Lewis acid such as BF3. OEt2 to give a cationic phosphenium complex fac-[(bpy)(CO)(3)Mo{PNN}](+), where an OMe on a phosphorus is abstracted as an anion. The facial isomer spontaneously isomerizes into its meridional form. Group 6 transition metal complexes, fac-[(bpy)(CO)(3)M{PXY(OMe)}] (M = Cr, Mo, W; XY = (NEt2)(2) N(Me)CH2CH2O, (NEt2)(OMe) and OCMe2CMe2O, (OMe)(2)) have been subjected to reaction with BF3. OEt2. These reactions reveal that the stability of cationic phosphenium complexes increases with: (i) going to a heavier congener; (ii) increasing the number of amino substituents on the phosphenium phosphorus; and (iii) adding an ethylene bridge between X and Y when at least one of X and Y is an amino substituent. The cationic phosphenium complex reacts with a nucleophile (Nu = OEt-, Me-) at the phosphenium phosphorus to give fac-[(bpy)(CO)(3)M{PXY(Nu)}], and also reacts with a tertiary phosphorus compound (L) to give [(bpy)(CO)(3)LM{PXY}](+). The reaction of a cationic monoaminomonoalkoxy phosphenium complex of Mo, mer-[(bpy)(CO)(3)Mo{PNO}](+) (PNO stands for PN(Me)CH2CH2O) with a diamino-substituted phosphorus compound, PNN(Y) OC = OMe, Oft, SEt, N(CH2)(3)CH2) proceeds with substitution for CO and then with the Y group migration to the coordinating phosphenium phosphorus to give [(bpy)(CO)(2){PNO(Y)}Mo{PNN}](+). The reaction isirreversible. Reactions of iron complexes containing a Group 14 element ligand (ER3; E = C, Si, Ge, Sn) and diamino-substituted phosphite, Cp(CO)(ER3)Fe{PNN(OMe)} with a Lewis acid have been examined. The reaction product depends on E. In any case, an OMe anion abstraction by a Lewis acid uniformlytakes place at the first stage of the reaction to give a cationic phosphenium iron complex containing an ER, ligand. The subsequent reaction is strongly dependent on E. When E is C, migratory insertion of the phosphenium ligand into the Fe-C bond or more simply an alkyl migration from Fe to phosphenium phosphorus occurs. When E is Si or Ge, the cationic phosphenium complex is stable and Fe-Si and Fe-Ge bonds remain intact. In contrast, when E isSn, one alkyl group on the Sn, and not SnR3, migrates to the phosphenium phosphorus to give a stannylene complex. The corresponding Ru complexes showsimilar reactions. X-ray structures of cationic phosphenium complexes of Mo and Fe have been employed and reveal that there is considerable double bond character between a transition metal and the phosphenium phosphorus. P-31- and Mo-95-NMR spectroscopic data also support the double bond character. Activation parameters concerning phosphenium ligand rotation along the P-Fe axis could be estimated from VT-NMR studies. (C) 2000 Elsevier Science S.A. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/04/20 alle ore 08:42:38