Yolande Lucchese

Zinc(II) and copper(II) complexes of monoanionic chelating phenolato ligands containing an amine donor. Crystal and molecular structure of the (Et3NH)[ZnCl2L] and CuL2 compounds with L=2-[(diethylamino)methyl]-4-methylphenolate

Abstract The reaction of ZnCl 2 with 2-[(diethylamino)methyl]phenol ( AH ) or 2-[(diethylamino)methyl]-4-methylphenol ( BH ) in the presence of NEt 3 (1:1:1 ratio) gave good yields of the complexes (Et 3 NH)[ZnCl 2 L] (L= A ( 1 ), B ( 2 )). Colourless crystals of 2 (monoclinic, P 2 1 / c , a =13.767, b =11.650, c =14.789 A, β =109.66°, Z =4, R =0.042) contain monomeric tetrahedral zincate anions in which the metal is surrounded by two Cl atoms and one bidentate aminophenolato ligand. The Et 3 NH + counter cation is hydrogen-bonded to the coordinated phenolate oxygen. Brown CuL 2 complexes (L= A ( 3 ), B ( 4 )) were obtained by reacting Cu(NO 3 ) 2 ·3H 2 O, CuCl 2 ·2H 2 O or CuSO 4 ·3H 2 O with AH and BH , respectively, in the presence of NEt 3 in a 1:2:2 Cu:ligand:NEt 3 ratio. Crystals of 4 (monoclinic, P 2 1 / c , a =8.165, b =14.798, c =9.481 A, β =90.91°, Z =2, R =0.048) contain monomeric square-planar copper centres surrounded by two bidentate aminophenolato ligands in a trans arrangement. The presence of relatively bulky ethyl substituents on the amino group favours the monomeric chelates by preventing the formation of phenolato-bridged polynuclear arrangements.

Bidentate phosphinophenol R2POH ligands. Oxo and imido Re(V) complexes of 2-diphenylphosphinomethyl-4-methylphenol (POH). Crystal structure of ReOCl(PO)2

Abstract The PPh 3 ligands were displaced and ReOCl 3 (POH) 2 ( 1 ) was formed when ReOCl 3 (PPh 3 ) 2 and 2 equiv. of the title ligand (POH) were refluxed in acetonitrile. In the presence of the proton quencher NEt 3 , ligand deprotonation took place and the bis-chelate complex ReOCl(PO) 2 ( 2 ) was isolated. Under similar conditions, ReO(OEt)(PO) 2 ( 3 ) was obtained from ReO(OEt)Cl 2 (PPh 3 ) 2 . NMR data are consistent with the trans -O–ReO- cis -P,P ‘twisted’ octahedral geometry for these species. The corresponding phenylimido complex Re(NPh)Cl(PO) 2 ( 4 ), similarly prepared from Re(NPh)Cl 3 (PPh 3 ) 2 , adopts the trans -O–Re–NPh- trans -P,P arrangement. The structure of 2 was confirmed by X-ray diffraction. The methylene group in the side-arm imparts flexibility to the chelate ring and allows the bond angles to be closer to the ideal octahedral values than in the corresponding diphenylphosphinophenolato compound. The six-membered rings adopt a flattened boat conformation bringing the phenolate unit out of the coordination plane and making the overall van der Waals envelope substantially different from that of the diphenylphosphinophenol-based complex.

Bidentate phosphinophenol ligands. Preparation and electrochemistry of the Re(III) complexes of 2-(diphenylphosphinomethyl)-4-methylphenol (P1OH) and 2-diphenylphosphinophenol (P2OH). Crystal and molecular structure of mer-Re[P1O]3

Abstract The reaction of 2-(diphenylphosphinomethyl)-4-methylphenol (P1OH) and 2-diphenylphosphinophenol (P2OH) on ReCl3(MeCN)(PPh3)2 in a 3:1 ratio leads to the formation of the homoleptic Re(III) complexes Re(P1O)3 (1) and Re(P2O)3 (2) in high yield. 1 is reasonably stable in air in the solid state and in solution, which is not the case for 2. Orange–red crystals of 1 contain distorted octahedral Re entities in which the metal is coordinated to three bidentate phosphinophenolato ligands in the mer configuration. Cyclic voltammetry of 1 and 2 shows two well defined monoelectronic quasi-reversible redox waves, one reductive attributed to the Re(III)/Re(II) couple and one oxidative due to the Re(III)/Re(IV) one. A second oxidative wave, attributed to the Re(IV)/Re(V) couple, is reversible only for 1, indicating the lower stability of 2 toward oxidation. In agreement with this, 2 gives, in air, the Re(V)-oxo species ReO(OP2O)(P2O)2 (3) quantitatively, whose structure is confirmed by X-ray diffraction.

Bidentate phosphinophenol ligand: synthesis and characterization of oxo and phenylimido rhenium(V) complexes of 2-diisopropylphosphinophenol

Abstract Six-coordinate, monosubstituted and disubstituted phosphinophenol complexes ReYX2(PPh3)(P∼O) and ReYX(P∼O)2 (Y=O, NPh; X=Cl, Br, I) were obtained by reacting 2-diisopropylphosphinophenol (P∼OH) with ReOX3(PPh3)2 and Re(NPh)X3(PPh3)2 in toluene. A mixture of the monosubstituted and disubstituted complexes ReYX2(PPh3)(P∼O) and ReYX(P∼O)2 was precipitated when the reactions were performed with a 2:1 ligand to metal ratio. Excess ligand (4 equiv.) was needed to obtain quantitatively the disubstituted complexes. 1H and 31P{1H} NMR show that all monosubstituted and disubstituted complexes exist as single isomers with a trans-P,P ‘twisted’ octahedral geometry, the site trans to the multiple bond being filled by the oxygen donor of one P∼O ligand. The compounds were also characterized by microanalysis, IR and mass spectrometry.

Synthesis, molecular and crystal structure of the zwitterionic Re(V)–oxo complex ReOCl3(L)(PPh3) with L=2-(diethylaminomethyl)-4-methylphenol

Abstract Ligand exchange between 2-(diethylaminomethyl)-4-methylphenol (N ∩ OH) and ReOCl 3 (PPh 3 ) 2 yields green crystals of the zwitterionic complex ReOCl 3 (O ∩ NH)(PPh 3 ). The X-ray diffraction study reveals that the structure consists of monomeric units in which the distorted octahedral coordination around Re is provided by the oxo group, the three Cl atoms in a mer arrangement, the PPh 3 ligand and the phenolate oxygen trans to the oxo group. The amino–phenol is monodentate via the phenolate oxygen, whereas the amine in the side-arm has been quaternized by migration of the phenol proton. The resulting ammonium group forms an intramolecular NH⋯Cl hydrogen bond with an adjacent Cl ligand, making the complex highly resistant to deprotonation. The 1 H NMR spectra indicate that the NH proton is not labile in CDCl 3 . Electron delocalisation along the OReOC(phenolate) moiety via the sp-hybridised oxygen of the end-on coordinated phenolate would be consistent with the short ReO(phenolate) distance of 1.915(3) A observed.

NICKEL(II) AND EUROPIUM(III) COMPLEXES OF THE AMINOPHENOL LIGAND: 2-(DIETHYLAMINO)METHYLPHENOL (N∼OH). CRYSTAL STRUCTURES OF THE Ni(N∼O)2 AND [Eu(NO3)3(HN∼O)2]2 COMPLEXES

Abstract The first Ni(II) compounds with aminophenol ligands were synthesized by reaction of 2-diethylaminomethylphenol and 2-diethylaminomethyl-4-methylphenol (N ∼ OH) with dehydrated NiCl2 in ethanol. They were characterized as tran-square planar Ni(N ∼ O)2 complexes by NMR and IR spectroscopies, mass spectrometry, elemental analysis and X-ray structure determination. When the ligand was reacted with Eu(NO3)3, the new dimeric complex [Eu(NO3)3(HN ∼ O)2]2 was isolated. Elemental analysis, IR, magnetic moment and X-ray diffraction indicated that in this case formally neutral aminophenol ligands, in their zwitterionic form, are attached to the metal center through the phenolato oxygen and act either as bridging or as terminal groups. Their protonated amino substituents are involved in strong N—H—O hydrogen bridging. The metal shows nine-coordination, the coordination sphere of each europium being completed by three NO3 groups.