Marie-Thérèse Youinou

Synthesis and molecular structure of a new family of iridium-(III) and rhodium(III) complexes: [(η5-Me5C5)Ir(LL)X]+ and [(η5-Me5C5)Rh(LL)Cl]+; LL = 2,2′-bipyridine or 1,10-phenanthroline; X = Cl or H. Single crystal structures of [(η5-Me5C5)Ir(bpy)Cl]Cl and [(η5-Me5C5)Rh(phen)Cl]ClO4

Abstract The four-coordinate d 6 title complexes were synthesized in nearly quantitative yield by reaction of 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen) in the presence of [Ir(η 5 -Me 5 C 5 )Cl 2 ] 2 or [Rh(η 5 -Me 5 C 5 )Cl 2 ] 2 . The hydride species were prepared in 80% yield by reduction of the chloro-complexes with sodium cyanoborohydride in ethanol/water. Both hydrido complexes of iridium show a characteristic singlet in the 1 H NMR spectrum δ −11.45 ppm for 2 and δ −11.35 ppm for 4 , and the corresponding metal-hydride stretchings appear at 2040 and 2090 cm −1 . [(η 5 -Me 5 C 5 )Ir(bpy)Cl]Cl crystallizes in the orthorhombic space group Pbca with unit cell parameters a 13.876(5), b 17.468(6), c 17.017(6) A. Refinement of 2392 observed reflections led to a value of R = 3.7 and R w = 5.0%. [(η 5 -Me 5 C 5 )Rh(bpy)Cl]ClO 4 crystallizes in the monoclinic space group P 2 1 / n with unit cell parameters a 8.191(4), b 12.200(5), c 22.222(8) A, and β 97.54(2)°. Refinement of 2223 observed reflections led to the final values of R = 3.9, and R w = 6.9%. Both complexes exhibit a characteristic three-legged “piano-stool” arrangement.

Synthesis and molecular structure of new families of iridium(III)-Cp★ and rhodium(III)-Cp★ complexes derived from 1,2-dicyanoethene-1, 2-dithiolate 2,2′-biimidazole or 2,2′-bithiazole. Single crystal structures of [(η5-Me5C5)Ir(biimH2)Cl]Cl and [(η5-Me5C5)Rh(dcdt)]

Reaction of [(η5-Me5C5)MCl2]2 (M  Ir or Rh) with 1,2-dicyanoethene-1,2-dithiolate (dcdt2−), 2,2′-biimidazole (biimH2), or 2,2′-bithiazole (bith) affords various d6 complexes in high yield. Pentacoordinate compounds such as [(η5-Me5C5)M(dcdt)] (M  Ir or Rh) and hexacoordinate complexes of the type [(η5-Me5C5)M(biimH2)Cl]Cl, (M  Ir or Rh) or [(η5-Me5C5)Ir(bith)Cl]Cl have been synthesized and characterized. [(η5-Me5C5)Rh (dcdt)] crystallizes in the orthorhombic space group C2221 with unit cell parameters a = 11.972 (3), b = 15.072 (4), c = 16.456 (5) A. Refinement of 859 observed reflections led to the final values of R = 2.31 and Rw = 3.46%. [(η5-Me5C5)Ir(biimH2)Cl]Cl crystallizes in the orthorhombic space group P212121 with unit cell parameters a = 14.610 (4), b = 14.556 (6), c = 8654 (3) A. Refinement of 1630 observed reflections led to a value of R = 186 and Rw = 2.65%. The biimH2-iridium complex exhibits a characteristic three-legged “piano-stool” arrangement and the dcdt-rhodium complex a flattened basket shaped arrangement.

Isomerization of 2-methyl-3-butyn-2-ol into prenal: mechanistic observations on tricomponent catalyst systems of the type Ti(OR)4–CuCl–R′CO2H. Crystal structure of [CuCl(Me2C(OH)CCH)]4

Abstract The mechanism of the title catalytic system was investigated, in particular by synthesizing several compounds that model the postulated metal–oxo–propargyloxo intermediates, such as [Ti(μ-O)(OBu t )(O 2 CTol)] 2 (Tol= p -MeC 6 H 4 ), Ti(OCMe 2 CCH) 4 and [CuCl(Me 2 C(OH)CCH)] 4 . The molecular structure of [CuCl(Me 2 C(OH)CCH)] 4 was determined by X-ray crystallography and heterobimetallic Ti–Cu complexes comprising the 2-methyl-3-butyn-2-oxo fragment are reported.

Rhodium (I) complexes of the dppn ligand, 3,6-bis (2′-pyridyl) pyridazine and X-ray structure of [Rh (CO) (dppn) (PPh 3 ) ] (PF 6 )

Abstract The reaction of the 3,6-bis (2′-pyridyl) pyridazine (dppn) ligand, with one and two equivalents of [Rh (CO) 2Sn] (PF6) , (s = THF) , yields respectively the mononuclear complex [Rh (CO) 2 (dppn) ] (PF6) 1 and the binuclear complex [Rh2 (CO) 4 (dppn) ] (PF6) 2 3. Furthermore, the reaction of 1 with PPh3 results in a substitution reaction to give [Rh (CO) (dppn) (PPh3) 2] (PF6) 2. The unsaturated complex 3 reacts with the monodentate phosphine PPh3 to yield a mixture of the known compound [Rh (CO) 2 (PPh3) 2] (PF6) and of the mononuclear [Rh (CO) (dppn) (PPh3) ] (PF6) 4, the crystal structure of which was established by X-ray diffraction. Moreover, 3 reacts with the bis (diphenylphosphino) methane (dppm) ligand in a 1 : 2 ratio to form the binuclear A-frame complex [Rh2 (CO) 2 (dppn) (μ-dppm) 2] (PF6) 2 5. However, the reaction of 3 with excess dppm (1 : 4 ratio) gives the known complex [Rh (CO) (dppm) 2] (PF6) 6.

Synthesis, X-ray molecular structure and electrochemical properties of a binuclear copper(I) complex with 2,7-diphenyl-azo-1,8-naphthyridine

Abstract The synthesis of 2,7-diphenyl-azo-1,8-naphthyridine (dpan) and its reaction with copper(I) are described. The X-ray study of the new entity [Cu 2 (dpan) 3 ](BF 4 ) 2 ( 1 ) reveals its molecular structure with two coppers separated by a distance of 3.526(1) A. The distorted tetrahedral environment about each copper is provided by one bridging tetradentate dpan ligand and the two remaining bidentate dpan ligands. The stabilization of the molecule may, in part, be due to a stacking interaction between the two bidentate dpan ligands. The weak interaction between. the copper(I) centers is confirmed by the electrochemical studies in CH 3 CN. 1 ·CH 2 CL 2 ,2C 6 H 6 ,CH 3 OH crystallizes in the triclinic space group P 1 (No. 2), a =15.443(7), b =19.826(7), c =13.763(6) A, α=108.90(2), β=113.21(2), γ=73.12(2)°, Z =2 and V =3599 A 3 at −100 °C. The structure was refined to R =6.6 and R w ,=10.3%, respectively, using 5876 reflections with I >3σ( I ) and 973 variables.

Electrochemical properties of bridged and non-bridged dinuclear copper complexes using a flexible ligand

Abstract We have investigated the redox behavior of a series of dinuclear copper(II) complexes Cu2L4+, Cu2(μ- OH)L3+ and Cu2(μ-Im)L3+ where L is 1,4-bis((1-oxa- 4,10-dithia-7-azacyclododec-7-yl)methyl)benzene, a ligand which is capable of holding two copper centers in close proximity. Electrochemical studies of the three dinuclear complexes in propylene carbonate reveal that Cu2L4+ exhibits a sequential two-electron reduction at the same positive potential whereas in Cu2(μ-OH)L3+ and Cu2(μ-Im)L3+ which involve bridging groups, reduction to their dinuclear CuI species occurs via two successive monoelectronic transfers at positive potentials. The relevance of these studies to those found for type III copper proteins is briefly discussed.

Synthesis and structure of a triply-chloro-bridged dimer of a homobinuclear RhI complex: [{Rh2(CO)(HC(PPh2)3)}2(μ-Cl)3]+[Rh(CO)2Cl2]−

Abstract The tripod ligand HC(PPh2)3 reacts with Mo(CO)3(CH3CN)3 yielding Mo(CO)3(CH3CN)(HC(PPh2)3). Reaction of this Mo0 complex with [Rh(CO)2Cl]2 gives unexpectedly the tetranuclear species [Rh2(CO)(HC(PPh2)3)]2(μ-Cl)+3 (3) which crystallizes as the Rh(CO)2Cl−2 salt (3a). This complex crystallizes in the monoclinic space group P21/c with Z = 4, with all dimensions a = 19.685(3), b = 19.524(3), c = 22.657(4) A, and β = 96.96(2)°. A direct route to the PF−6 salt of 3 (3b) is also presented. The 31P NMR data show 3a and 3b to be identical and that the tetranuclear structure is retained in solution, i.e. two units of binuclear RhI species bridged by three chlorine atoms. In each binuclear unit, the tripod ligand spans two RhI which are linked directly by a metal-metal bond (RhRh = 2.696 A).