Preparation and characterization of the dimetallo ketone complexes Ir2(.mu.-S-tert-Bu)2(.mu.-CO)L2(CO)2I2: crystal and molecular structure of the [iridium] complex where L = trimethylphosphine (original) (raw)
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Organometallics, 1982
Several oxidative reactions of different halogens to dinuclear complexes Ir2(~-t-BuS)z(CO)zLz (L = CO, P(OMe)3, PMezPh, PMeJ have been carried out in nondonor solvents such as toluene or dichloromethane. Different behavior has been observed depending upon the nature of the halogen. Addition of 1 molar equiv of iodine leads to quantitative formation of Ir(I1) complexes of general formula Irz(~-t-BuS)z(CO)zLzIz. Further addition of a second molar equivalent of iodine gives rise to dinuclear iridium(II1) compounds Ir2(~-t-BuS)2(CO)2L21~ Isomorphous complexes have been formed by addition of bromine. However, Ir(I1) species could never be prepared quantitatively since Ir(II1) complexes are always formed preferentially. Oxidative addition of chlorine has also been observed. However, substitution of both thiolato groups by chlorine atoms to give Ir(II1) dinuclear complexes, Ir2(~-Cl),(C0),L2Cl4, is a competitive process. An X-ray diffraction study of Ir2(p-t-BuS)2(CO)z(PMe2Ph)212 has been performed. This compound crystallizes with four formula units in the monoclinic space group Cih-P2,/c in a cell of dimensions a = 16.997 (2) A, b = 14.911 (3) A, c = 13.411 (3) A, and 0 = 91.17 (1) O. On the basis of 3390 unique reflections the structure was refined by full-matrix least-squares techniques to conventional indices R(F) = 0.046 and R,(F) = 0.055. The molecular architectwe of this dinuclear complex can be described in terms of two square-planar pyramids around each iridium atom sharing an edge formed by the two sulfur atoms. The flap angle between the two basal planes is 83.8O. The two iodine atoms occupy the two axial positions, and the two phosphine ligands are mutually cis; the Ir-Ir separation is of 2.702 (1) A. Other bond distances of interest are the following: Ir (1)-1(1) = 2.742 (2) A, Ir(2)-1(2) = 2.712 (2) A, Ir(l)-P(l) = 2.318 (5) A, Ir(2)-P(2) = 2.311 (5) A, Ir (1)-S(1) = 2.383 (5) A, Ir(l)-S(2) = 2.373 (5) A, Ir(2)-S(1) = 2.372 (5) A, Ir(2)-S(2) = 2.391 (5) A.
Organometallics, 1985
Thiolato-bridged diiridium(1) complexes [Ir(r-t-BuS)(CO)L],, 1, react with dihalomethane to yield quantitatively [IrX(p-t-BuS)(CO)LI2[p-CH2], 2 (X = I, L = CO, P(OMe),, PPh,, PPh2Me, PMe,; X = Br, L = PPh,). Cis and trans isomers were observed in two cases. A crystal structure determination of [IrI(p-t-BuS)(CO) (P(OMe),],(p$H,] was carried out by X-ray diffraction. The compound crystallizes in orthorhombic space group D,-Pbca in a cell of dimensions a = 17.033 (3) A, b = 15.632 (2), and c = 23.808 (3) A, with 2 = 8. On the basis of 3106 unique reflections having F,2 > 4a(F:), the structure was refined by full-matrix least-squares technique to conventional agreement indices of R = 0.024 and R, = 0.027. Each iridium atom is octahedrally coordinated, being bound to one carbonyl, one phosphite, one iodide ligand, two bridging S atokns of the thiolato ligands, and the bridging C atom of the CH2 group. The phosphite ligands (and the carbonyl ligands) are in a trans arrangement. The t-Bu groups are in an anti conformation with respect to the Ir2Sz core. The IrIr separation is 3.1980 (4) A. In solution, complexes 2 undergo syn-anti isomerization on the NMR time scale. The halogen abstraction reaction of 2 by silver(1) salts and the subsequent addition of nucleophilic reagents to the cationic species so obtained are described together with the molecular structure of the products. Following our studies of the reactivity of thiolato-bridged homobimetallic species toward small molecule^,^ we present here t h e preparation of novel p-methylene complexes [I~X(~-~-BUS)(CO)L]~[~-CH,] (2) via quantitative double oxidative addition reactions of dihalomethane with diiridium(I) complexes [ Ir (p-t-BUS) (CO) L] 2, 1. These p-methylene complexes afford cationic species through halogen abstraction. It is t h e vacant sites so obtained which make these electron-deficient species, whose reactivity is introduced in this paper, of particular interest. Experimental Section General Remarks. All reactions and manipulations were routinely performed under a nitrogen or argon atmosphere in Schlenk-type glassware. All solvents were appropriately dried and freed from molecular oxygen prior to use. Microanalyses were performed by the Service Central d'Analyse du
Inorganic Chemistry, 2008
The reaction of gem-dithiol compounds R 2 C(SH) 2 (R = Bn (benzyl), i Pr; R 2 =-(CH 2) 4-) with dinuclear rhodium or iridium complexes containing basic ligands such as [M(µ-OH)(cod)] 2 and [M(µ-OMe)(cod)] 2 , or the mononuclear [M(acac)(cod)] (M = Rh, Ir, cod = 1,5-cyclooctadiene) in the presence of a external base, afforded the dinuclear complexes [M 2 (µ-S 2 CR 2)(cod) 2 ] (1-4). The monodeprotonation of 1,1-dimercaptocyclopentane gave the mononuclear complex [Rh(HS 2 Cptn)(cod)] (5) that is a precursor for the dinuclear compound [Rh 2 (µ-S 2 Cptn)(cod) 2 ] (6). Carbonylation of the diolefin compounds gave the complexes [Rh 2 (µ-S 2 CR 2)(CO) 4 ] (7-9) which reacted with P-donor ligands to stereoselectively produce the trans isomer of the disubstituted complexes [Rh 2 (µ-S 2 CR 2)(CO) 2 (PR' 3) 2 ] (R' = Ph, Cy (cyclohexyl)) (10-13) and [Rh 2 (µ-S 2 CBn 2)(CO) 2 {P(OR') 3 } 2 ] (R' = Me, Ph) (14-15). The substitution process in [Rh 2 (µ-S 2 CBn 2)(CO) 4 ] (7) by P(OMe) 3 has been studied by spectroscopic means and the full series of substituted complexes [Rh 2 (µ-S 2 CBn 2)(CO) 4-n {P(OR) 3 } n ] (n = 1, 4) has been identified in solution. The cis complex [Rh 2 (µ-S 2 CBn 2)(CO) 2 (µ-dppb)] (16) was obtained by reaction of 7 with the diphosphine dppb (1,4bis(diphenylphosphino)butane). The molecular structures of the diolefinic dinuclear complexes [Rh 2 (µ-S 2 CR 2)(cod) 2 ] (R = Bn (1), i Pr (2); R 2 =-(CH 2) 4-(6)) and that of the cis-complex 16 have been studied by X-ray diffraction.
Polyhedron, 1997
Ruthenium(II) complexes [Ru(R-acda)2(PPh3)2] (la-e.), [Ru(R-acda)(bpy)2](CIO4)(2a-d), [Ru(Racda)(phen)~](CIO4)(2e-g), [Ru(R2-dtc)(bpy)2](ClO4)(3a, b) and [Ru(R2-dtc) (phen)2](C104)(3c, d) (where R-acdaH =2-alkylamino-l-cyclopentene-l-dithicarboxylic acid, R2-dtcNa=sodium N,N'-dialkyl dithiocarbamate, bpy = 2,2'-bipyridine and phen = 1,10-phenanthroline) have been synthesized and characterized. The tH NMR spectra of the phosphine complexes (la-e) show that, with the increase in the chain length of the alkyl group of R-acda-, the N-alkylamino proton becomes more deshieided and is accompanied by a shift of the NH stretching frequency v(NH) to lower energy. A linear relationship is obtained between the chemical shift cS(NH) and v(NH). All the complexes exhibit absorption bands due to dn ~ ~* (bpy, phen or PPh3), d~z ~* (R-acda-or R2-dtc-) charge transfer transitions and n ~ it* intraligand transition. Complexes la-e undergo two irreversible oxidations, Ru H-* Ru m and Ru m ~ Ru w, while the other complexes (2, 3) exhibit one reversible (RuU/Ru In) and one irreversible (Ru lu-* Ru Iv) oxidation process.
New Journal of Chemistry, 2011
Reaction of the Ir(III) dimer [(η5-C5Me5)IrCl2]2 with PMeXyl2 (Xyl = 2,6-C6H3Me2), in the presence of the poorly coordinating base 2,2,6,6-tetramethyl piperidine, gives a chloride complex 1-Cl, resulting from hydrogen chloride elimination involving one of the phosphine benzylic hydrogen atoms and concomitant cyclometallation. Related compounds containing other halide or pseudohalide ligands, 1-Br, 1-Cl, 1-SCN, can be made, the latter featuring Scoordination of the ambidentate thiocyanate to the soft Ir(III) Lewis acid centre, as suggested by IR data and demonstrated by X-ray crystallography. Hydride 2-H, and alkyl derivatives 3 (Me) and 4 (CH2SiMe3) can also be prepared from 1-Cl and appropriate hydride and alkylating reagents. An interesting H/D exchange chemistry that occurs in the presence of CD3OD has been disclosed for 1-Cl, 1-Br and 2-H. For the halide derivatives, deuterium incorporation takes place into the methylene and methyl sites of their cyclometallated ligand, whereas for 2-H only the hydride and methylene (Ir-CH2) protons participate in the exchange, which is strikingly accelerated by catalytic amounts of acids.
Inorganica Chimica Acta, 2008
The reaction of [(g 4 -1,5-C 8 H 12 ) 2 Ir 2 (l-Cl) 2 ] with 2-di-t-butylphosphino-2 0 -methylbiphenyl (t-Bu 2 Pbiph Me ) in the presence of AgBF 4 afforded the dichlorido-bridged Ir-Ag complex [(g 4 -1,5-C 8 H 12 )Ir(l-Cl) 2 Ag(t-Bu 2 Pbiph Me )] (1) which was fully characterized by a single crystal X-ray diffraction study. Sequential treatment of the diiridium precursor first with the silver salt and then with the phosphine yielded cyclometalated [(g 4 -1,5-C 8 H 12 )Ir(t-Bu 2 Pbiph Me -H + )] (2). Detailed DFT calculations gave evidence that the phosphine ligand of 2 forms a strained four-membered iridaheterocycle through orthometalation rather than a sterically congested six-membered chelate structure through C-H activation on the remote phenyl ring. The phosphonium salt [t-Bu 2 P(H)biph Me ]BF 4 was isolated as a by-product of the preparations of 1 and 2; its crystal structure was determined.
Inorganic Chemistry, 2013
This work details the synthesis and structural identification of a series of complexes of the (η 5 -C 5 Me 5 )Ir(III) unit coordinated to cyclometalated bis(aryl)phosphine ligands, PR′(Ar) 2 , for R′ = Me and Ar = 2,4,6-Me 3 C 6 H 2 , 1b; 2,6-Me 2 -4-OMe-C 6 H 2 , 1c; 2,6-Me 2 -4-F-C 6 H 2 , 1d; R′ = Et, Ar = 2,6-Me 2 C 6 H 3 , 1e. Both chloride-and hydride-containing compounds, 2b−2e and 3b−3e, respectively, are described. Reactions of chlorides 2 with NaBAr F (BAr F = B(3,5-C 6 H 3 (CF 3 ) 2 ) 4 ) in the presence of CO form cationic carbonyl complexes, 4 + , with ν(CO) values in the narrow interval 2030−2040 cm −1 , indicating similar π-basicity of the Ir(III) center of these complexes. In the absence of CO, NaBAr F forces κ 4 -P,C,C′,C″ coordination of the metalated arm (studied for the selected complexes 5b, 5d, and 5e), a binding mode so far encountered only when the phosphine contains two benzylic groups. A base-catalyzed intramolecular, dehydrogenative, C−C coupling reaction converts the κ 4 species 5d and 5e into the corresponding hydrido phosphepine complexes 6d and 6e. Using CD 3 OD as the source of deuterium, the chlorides 2 undergo deuteration of their 11 benzylic positions whereas hydrides 3 experience only D incorporation into the Ir−H and Ir−CH 2 sites. Mechanistic schemes that explain this diversity have come to light thanks to experimental and theoretical DFT studies that are also reported.
Organometallics, 2005
The cis-[RuCl 2 (PPh 3 ) 2 (N-N)] (N-N ) bipy (1), Me-bipy (2), phen (3), and bathophen (4)) complexes were used to synthesize five new electron-rich phosphine-containing complexes cis-[RuCl 2 (dcype)(N-N)] (N-N ) bipy (1a), Me-bipy (2a), phen (3a), and bathophen (4a)) and cis-[RuCl 2 (PEt 3 ) 2 (bipy)] (1c) by phosphine exchange. These complexes were obtained and characterized by NMR ( 31 P{ 1 H}, 1 H), cyclic voltammetry, and elemental analysis. Electrochemical studies of these complexes reveal a single reduction process (Ru III /Ru II ). These complexes are more easily oxidized than their analogues cis-[RuCl 2 (dppb) ]. The reactivity of complexes cis-[RuCl 2 (dcype)(N-N)] with carbon monoxide was tested, and dissociation of one chloride was observed, leading to the formation of four new cationic species with general formula [RuCl(CO)(dcype)(N-N)](PF 6 ) (bipy (1b), Me-bipy (2b), phen (3b), and bathophen (4b)). The complexes described here and elsewhere with general formulas cis-[RuCl 2 (P-P)(N-N)], [RuCl(CO)(dcype)(N-N)](PF 6 ), and cis-[RuCl 2 (P) 2 (N-N)] were used as precatalysts in the transfer hydrogenation of functionalized aryl-ketones, and most of them were active. X-ray structures of cis-[RuCl 2 (PEt 3 ) 2 (bipy)] (1c) and [RuCl(CO)(dcype)(bipy)]-(PF 6 ) (1b) will be presented.