Gérard Commenges

Rhodium-catalysed hydroamination-hydroarylation of norbornene with aniline, toluidines or diphenylamine

Abstract The condensation of aniline, toluidines or diphenylamine with norbornene tetrahydrofuran is promoted by a system generated from Li n Bu, ArNH 2 and [(PEt 3 ) 2 RhCl 2 ]. Aniline and m - and p -toluidines lead to a mixture of hydroamination and hydroarylation products whereas o -toluidine and diphenylamine lead to the hydroarylation product only. When conducted in the amine as solvent, the reaction is catalytic with respect to both lithium and rhodium.

NMR (195Pt and 13C) contribution to the study of some Pt(II), Pt(IV) and mixed-valence thioamido complexes

Abstract The 195 Pt and 13 C chemical shifts (δ Pt and δ c ) are reported for platinum(II), platinum(IV) and class II mixed-valence complexes, with general formula [PtL 4 ]X 2 , cis - and trans -PtL 2 X 2 , PtL 2 X 4 and Pt 2 L 4 X 6 (where L may be thiourea, 2-imidazolidine-thione, tetrahydro 2-pyrimidinethione, thiocaprolactam, pyridine-2-thione and tetramethylthiourea, and X may be Cl or Br). The 195 Pt chemical shifts can be understood in view of 13 C data in terms of variations of electronegativities and σ-donor abilities of ligands attached to platinum.

Gallium-71, carbon-13 and hydrogen-1 NMR studies of the interactions of pyridoxal 5′-phosphate isonicotinyl hydrazone with gallium in aqueous solution

Abstract Ga(III) binding by the new ligand pyridoxal 5′-phosphate isonicotinyl hydrazone (PPL-INH) has been investigated by 71 Ga, 13 C and 1 H NMR. PPL-INH forms a strong complex with gallium. 71 Ga NMR studies are based on the observation of the Ga(OD) − 4 signal, which allows the determination of the 2:1 stoichiometry for the complex. The complexation sites are shown by 13 C NMR. The complex is water-soluble from pH 6 to pH 11, a deprotonated form of the ligand being stabilized by gallium. This work initiates the study of pharmacologic properties of a family of complexes of gallium with hydrazones.

Bonding interactions between three adjacent hydrogen ligands. Preparation and spectroscopic properties of the tantalum and niobium complexes [Ta(H)3(C5H5–nRn)2](R = SiMe3, n= 1 or 2) and [Nb(H3)(C5H5–nRn)2](n= 1, R = Me or SiMe3; n= 2, R = SiMe3)

The new title complexes of tantalum are true hydrides whereas the niobium complexes have bonding interactions among the three hydrogen atoms, as evidenced by short n.m.r. T1 values and unusual couplings 1J(H,H) which vary with temperature from less than 3 to about 100 Hz.

New route to bimetallic imidazolate-bridged complexes. II: NMR study of dinickel complexes. Importance of the non-bonded interactions

Abstract A series of methyl-substituted imidazole complexes of the (AENi) moiety (AE being the anionic form of 7-amino-4-methyl-5-aza-3-hepten-2-one) and of the related dinickel imidazolate-bridged complexes was prepared. 1 H and 13 C NMR data at 295 and 203 K are reported for the free ligands and their mononuclear and dinuclear complexes. Consideration of the whole set of data with a particular emphasis on the influence of the temperature points to the importance of non-bonded interactions. Complexing the (AENi) moiety with 4/5-MeImH yields a mixture of the two mononuclear isomers, [(AE)Ni4-MeImH] + and [(AE)Ni5-MeImH] + , the latter being largely predominant.

Mononuclear lanthanide complexes of tripodal ligands: synthesis and spectroscopic studies

Abstract Lanthanide complexes of the tripodal ligand derived from the reaction of salicylaldehyde with tris (2-aminoethyl)amine have been obtained for the first time. The experimental procedure necessitates deprotonation of the ligand with a strong base prior to the addition of the lanthanide ion. These quite stable neutral complexes have been characterized by mass spectrometry (FAB+), 1D and 2D-NMR ( 1 H – 1 H COSY and 1 H – 13 C heteronuclear multiple quantum correlations). The corresponding complexes of the substituted tripodal ligand prepared from 3-methoxysalicylaldehyde have also been isolated and characterized.

Variable temperature multidimensional NMR study of anionic Rh(I) anilido [(R3P)2Rh(NHPh)2]−, M+ complexes

Variable temperature multidimensional NMR studies of [(R3P)2Rh(NHPh)2]−, Li+ complexes enabled the detection of activation of one aromatic ortho proton of each anilido ligand. This activation is not attributable to a CHoRh agostic interactions, but rather to interaction with lithium, resulting from a short distance between the lithium atom and one of the aromatic ortho hydrogens of each anilido ligand.

Upon the existence of a trihydrogen ligand. Preparation and spectroscopic studies of the adducts (C5Me5) RuH3P(cyclo-C6H11)3·CuCl and [{(C5Me5)RuH3P(cyclo-C6H11)3}2Cu]PF6

(C5Me5)RuH3PCy3(1)(Cy = cyclohexyl) reacts smoothly with 1/n[CuCl]n in toluene and with 1 or 1/2 equivalent of [Cu(MeCN)4]PF6 in tetrahydrofuran (THF) to give (C5Me5)RuH3PCy3CuCl (2) and {(C5Me5)RuH3PCy3)2Cu}PF6(3) respectively, and the anomalous n.m.r. behaviour of (1) characterized in particular by the observation of AB2 spectra showing large temperature dependent AB coupling constants is preserved in (2) whereas in (3) a disymmety is observed in agreement with the presence of one hydride and one dihydrogen molecule; an interpretation is given and a model taking into account these data is proposed for the structure of the ‘trihydrogen’ derivatives.

Geometrical and optical isomers of the dinickel complexes of two chiral ligands of the N,N′-disubstituted oxamide type: 1D and 2D NMR study

Abstract Two novel chiral dinucleating ligands have been obtained by grafting a methyl substituent onto one and both diamino arm(s) of N,N′ -bis(4-methyl-5-aza-3-hepten-2-one-7-yl) oxamide (H 4 L 1 ), respectively. These ligands, N -(4-methyl-6-oxo- -3-azahepta-4-enyl)- N′ -(1,4(2,4)-dimethyl-6-oxo-3-azahepta-4- enyl) oxamide (H 4 L 2 ) and N,N′ -(1,4(2,4)-dimethyl-6-oxo-3- azahepta-4-enyl) oxamide (H 4 L 3 ), and their related nickel complexes (Ni 2 L 2 ) and (Ni 2 L 3 ) exist as a variety of geometrical and optical isomers since, on the one hand, two locations are possible for each substituent and on the other hand, each substituted amino chain comprises an asymmetric carbon. All but one geometrical isomer have been isolated via unequivocal synthetic pathways. Definitive proofs of the existence of all geometrical and optical isomers are gained from an NMR study including 2D spectra and 1D spectra obtained in the presence of a chiral auxiliary. In all cases the five- membered ring resulting from coordination of the diamino moiety of the ligands to the nickel ion adopts a preferred conformation which places the methyl substituent in an axial or pseudoaxial position.

Discrimination between two isomeric platinum mixed-valence complexes by means of 13C n.m.r. spectroscopy (solution and solid state)

Two novel isomeric thioamido mixed-valence complexes of platinum have been distinguished by 13C n.m.r. spectroscopy (solution and solid state).