Guy Bertrand

1,2,4-Triazolium-5-ylidene and 1,2,4-triazol-3,5-diylidene as new ligands for transition metals

Ab initio calculations show the 1,2,4-triazolium-5-ylidene (3a) and 1,2,4-triazol-3,5-diylidene (4a) are true minima on the potential surface. As expected, 4a is much higher in energy than its triazole isomers 5a, 6a and 8a and the 1,2,4-triazol-3-ylidene (7a). Sodium methoxyde adds to the diquaternary salt of 1,2,4-triazoles (9b,c) to give the corresponding monocationic heterocycles 10b,c in 70 and 50% yield, respectively. One equivalent of silver(I) acetate reacts with 9b leading to the bis(1,2,4-triazolium-5-ylidene)silver(I) complex (11b) in 80% yield. Under the same experimental conditions, but using two equivalents of silver(I) acetate, solid-state one-dimensional polymers 12′b,c featuring the coplanar 1,2,4-triazol-3,5-diylidene ligands coordinated to silver(I) are obtained in 90% yield. 12′c has been fully characterized including a single-crystal X-ray diffraction study.

A new route to bis(2,4,6-tri-tert-butylphenyl)diphosphene via silylated compound

Abstract A new synthesis of stable diphosphene is reported. δ 31 P value is reinvestigated.

Synthesis, Characterization and Dynamic Behavior of Mono- and Dinuclear Palladium(II) Carbene Complexes Derived From 1,1′-Methylenebis(4-alkyl-1,2,4-triazolium) Diiodides

Mononuclear palladium carbene complexes 2a–c and 3 derived from 1,1′-methylenebis(4-alkyl-4,5-dihydro-1H-1,2,4-triazole-5-ylidene) have been obtained by the reaction of 1,1′-methylenebis(4-alkyl-1,2,4-triazolium) diiodides 1a–d with palladium acetate under mild conditions. The mononuclear complexes 2a–c have been transformed into their corresponding trans-binuclear complexes 4a–c. All compounds were characterized by spectroscopic techniques and the dynamic behavior of 2a–cand 4a–c has been studied. The X-ray structures of 2a and 4c are reported.

The Deprotonated Iminophosphorane o-C6H4PPh2P=NSiMe3 as a Novel Chelating Ligand in Organocopper(I) and -zinc(II) Chemistry

Lithiation of triphenyl(trimethylsilylimino)phosphorane Ph3P=NSiMe3 with MeLi gives the ortho-metallated species [Li(o-C6H4PPh2NSiMe3)]2·Et2O (1), which exhibits all the requirements of an organometallic ligand capable of side-arm donation. The deprotonated ortho-phenyl carbon atom gives access to metal–carbon σ bonds in transmetallation reactions, while the Ph2P=NSiMe3 moiety can donate to the same metal center through the imine nitrogen atom. In transmetallation reactions with CuBr, the dimeric organocopper complex [Cu(o-C6H4PPh2NSiMe3)]2 (2) is obtained, while application of ZnCl2 yields the monomeric zinc complex [Zn(o-C6H4PPh2NSiMe3)2] (3). Reaction with CuCl2 gives access to the new diiminophosphorane (o-C6H4PPh2NSiMe3)2 (4) through oxidative coupling at the ortho positions. In all the metal complexes, the Ph2P=NSiMe3 residue acts as a side-arm donating group through the nitrogen atom. The intermolecular NCu donor bond in 2 is as short as copper–amide bonds, while the NZn bond lengths in 3 are in the region normally found for donor bonds. Compound 4 is a molecule, possessing two Ph2P=NSiMe3 moieties bridged by a biphenylene group.

Photolytic rearrangement of phosphorus azide : evidence for a transient metaphosphonimidate.

Durch Photolyse von Diphenyl-phosphorylazid (I) entsteht intermediar das Metaphosphonimidat (II), das in Abwesenheit von reaktiven Komponenten zum Dimeren (III) abreagiert.

Transition metal complexes and cycloaddition products of pentafluorophenyl isocyanide

Abstract Reactions of pentafluorophenyl isocyanide with pentacarbonyl (η 2 - cis -cyclooctene)chromium, tricarbonyl (η 6 - cycloheptriene)tungsten, and tetracarbonylnickel yield pentacarbonyl(pentafluorophenyl isocyanide)chromium I, mer -tricarbonyl- tris(pentafluorophenyl isocyanide)tungsten II, and tetrakis(pentafluorophenyl isocyanide)nickel III, respectively. The meridial structure of tricarbonyltris(pentafluorophenyl isocyanide)tungsten was elucidated by X-ray crystallography. The [2+1] cycloaddition reaction of pentafluorophenyl isocyanide with the diphosphene RPPR [RC(SiMe 3 ) 3 ] yields the three membered heterocyclic diphosphirane imine IV. The photolysis of pentafluorophenyl isocyanide in the presence of [bis(diisopropylamino)phophino]-(trimethylsilyl)diazomethane yields 1-pentafluorophenyl-2,4-bis(diisopropylamino)- 3-trimethylsilyl-1,2-azaphosphetine V according to the results of an X-ray structure analysis at −158°C.

Stannylene and germylene as powerful dechlorinated reagents. New route to diphosphene.

Abstract Dichlorophosphines RPCl2 [R=Cl ( 3 ), Ph ( 4 ) and 2,4,6-But3C6H2 ( 5 ] are reduced to the corresponding phosphorus-I compounds by the stannylene Me2Si (NBut)2Sn: ( 1 ) or by the germylene GeI2 ( 2 ) ; in the case of the reaction of ( 5 ) with ( 1 , bis(2,4,6-tri-tert-butylphenyl)-diphosphene ( 9 ) is obtained with a 65 % yield.

Photolytic rearrangement of germanium azides. Evidence for transient germa-imines

Abstract Photolysis of germanium azides gives rise to transient germa-imines which have been quantitatively trapped by pinacol. Evidence for the formation of diphenylgermylene in the photolysis of hexaphenylcyclodigermazane is also reported.

First structural characterization of an α-diazophosphane: crystal structure of bis[bis(diisopropylamino)phosphanyl]diazomethane [(i-Pr2N)2P]2CN2

Crystals of bis[bis(diisopropylamino)phosphanyl]diazomethane P2N6C25H56, M = 502.7 belong to the monoclinic space group, C2/c with a 12.044(2), b 28.661(4) c 10.301(1) A, β 116.13(1)°, V 3192(2) A3 and Z = 4. The structure was refined by use of 1275 non zero Mo-Ka reflections to R = 0.052 at 293 K. The unit cell contains discrete monomeric molecules. The structural parameters of the CN2 group are very close to those found for other diazoalkanes. The linear diazo group C(1)N(1)N(2) lies on the crystallographic two fold axis of the unit cell. The ability of bis[bis(diisopropylamino)phosphanyl]diazomethane to act as a chelating or reducing agent is discussed.

Synthese et rearrangements de cycles α-fonctionnels du germanium: oxa-6 diphenyl-2,2 germa-2 bicyclo[3.1.0] hexane et diphenyl-1,1 germa-1 cyclopentanol-2. etude comparative avec les derives isologues du silicium

Abstract The synthesis of 1,1-diphenyl-1-germacyclopent-2-ene from its β-ethylenic isomer is described. 6-Oxa-2,2-diphenyl-2-germabicyclo[3.1.0]hexane, prepared by oxidation of the α-ethylenic ring with peracid, leads, by thermal rearrangement, to a mixture of 1-oxa-2-germacyclohex-5-ene and 1-germacyclopentan-3-one. 1,1-Diphenyl-1-germacyclopentan-2-ol, synthesised by hydroboration—oxidation from the germacyclopent-2-ene, gives on treatment with sodium 1-oxa-2,2-diphenyl-2-germacyclohexane and 4-diphenylhydrogermylbutan-1-ol. Results recorded with organogermanium rings are compared with isologous silicon derivatives.