119Sn‐ and 31P‐NMR. Spectroscopy of the 5‐coordinate complexes [Rh (SnClnBr(3−n)) (norbornadiene) (tertiary phosphine)2]

Garrlda, Maria; García, Victoria; Kretschmer, Matthias; Pregosin, Paul S.; Rüegger, Heinz

doi:10.1002/hlca.19810640421

Cited by 20 publications

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References 29 publications

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“…In the present study, we are concerned with the structure, stereochemistry, electrochemistry, and reactivities of copper(I) and copper(II) complexes of the ligands 6,6‘-bis(bromomethyl)-2,2‘-bipyridine (bpy-Br 2 ) and 6,6‘-bis(chloromethyl)-2,2‘-bipyridine (bpy-Cl 2 ) in combination with chloride, bromide, and perchlorate ions. Although exchange reactions are common for the elements of groups 12−17 and the reactions involving halides of metallic and nonmetallic elements have been widely studied, to our knowledge, exchange reaction between carbon−halogen and metal−halogen bonds are quite uncommon. We report here that the tetracoordinate copper(II) complex [Cu II (bpy-Br 2 )Cl 2 ], undergoes halogen exchange and scrambling to produce [Cu II (bpy-Br 2- x Cl x )Cl 2- y Br y ] complexes.…”

Section: Introductionmentioning

confidence: 99%

Halogen Exchange and Scrambling between C−X and M−X‘ Bonds in Copper, Nickel, and Cobalt Complexes of 6,6‘-bis(bromo/ chloromethyl)-2,2‘-bipyridine. Structural, Electrochemical, and Photochemical Studies

et al. 2007

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The synthesis, reactivities, spectroscopic, electrochemical, and structural studies of copper(I), copper(II), nickel(II), and cobalt(II) complexes of 6,6'-bis(bromomethyl)-2,2'-bipyridine (bpy-Br2) and 6,6'-bis(chloromethyl)-2,2'-bipyridine (bpy-Cl2) have been reported. The copper(I) complex [CuI(bpy-Br2)2](ClO4) (1) has been obtained in two crystallographic modifications, in which the coordination geometry of the metal center has the D2d symmetry. The reaction between CuCl2.2H2O and bpy-Br2 has been followed spectrophotometrically at 45 degrees C over a period of 7 h, and a mechanism for the intramolecular halogen exchange and scrambling in the initially formed compound [CuII(bpy-Br2)Cl2] (5) has been proposed. Depending upon the reaction conditions, several halogen-exchanged products, namely [CuII(bpy-Br1.86Cl0.14)(Cl1.89Br0.11)] (2), [CuII(bpy-Br1.81Cl0.19)(Cl1.70Br0.30)(H2O)] (3), and [CuII(bpy-Br0.63Cl1.37)(Cl0.54Br1.46)] (4), have been isolated in crystalline form. The reaction between bpy-Cl2 and CuCl2.2H2O provides [CuII(bpy-Cl2)Cl2] (7) and [CuII(bpy-Cl2)Cl2(H2O)] (8), whereas CoCl2.6H2O and NiCl2.6H20 on reaction with bpy-Br2 under boiling condition produce [CoII(bpy-Br0.5Cl1.5)(ClBr)] (11) and [NiII(bpy-Br0.46Cl1.54)(Cl0.73Br1.27)(H2O)] (12), respectively. The X-ray structures determined for the 4-coordinate compounds 2, 4, and 7 show flattened tetrahedral geometry for the metal center with the D2 symmetry. Both 5-coordinate compounds 3 and 12 have square pyramidal geometry, and whereas the nickel(II) complex 12 has near-perfect geometry (tau = 0.015), considerable distortion is observed for the copper(II) complex 3 (tau = 0.25). Complexes [CuII(bpy-Cl2)Br2] (6) and [CuII(bpy-Br2)Br2] under boiling condition undergo photoreduction to produce the dimeric copper(I) complexes [{CuI(bpy-Cl1.30Br0.70)(mu-Br)}2](9) and [{CuI(bpy-Br2)(mu-Br)}2] (10), respectively. The fact that the photoreduction of [CuII(bpy-Cl2)Br2] (6) and [CuII(bpy-Br2)Br2] do not take place in absence of light has been established by spectrophotometric measurements. The crystal structures of 9 and 10 have been determined. The electrochemical behavior of all the copper complexes 1-10 has been studied in acetonitrile and dichloromethane. The E1/2 values for the CuI/CuII redox couples show strong solvent dependence and for a given system the E1/2 value is more positive in dichloromethane relative to that in acetonitrile. For the compounds [CuII(bpy-Br2-xClx)(Cl2-yBry)] (x = 0-2, y = 0-2), the E1/2 values become more positive with the increase of y value.

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Section: Introductionmentioning

confidence: 99%

Halogen Exchange and Scrambling between C−X and M−X‘ Bonds in Copper, Nickel, and Cobalt Complexes of 6,6‘-bis(bromo/ chloromethyl)-2,2‘-bipyridine. Structural, Electrochemical, and Photochemical Studies

et al. 2007

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Stannylalkynes as Starting Materials for the Synthesis of Vinylidene Rhodium Complexes and of Heterodimetallic Compounds Containing a Rh—Hg or Rh—Sn Bond

1994

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(2 e ) and [ Rh( C=CCH20Me) (HgPh) C1( PiPr3) (6d) have been determined.Currently, there is much interest in the chemistry of vinylidene transition-metal complexes[*], which are key species in the transformation of two-carbon ligands and play an important role in organometallic as well as in organic synthesisL31. After we had discovered that not only terminal alkynes H C 4 R but also trimethylsilyl and triphenylsilyl derivatives, RC=CSiMe3 and RC=CSiPh3, can be converted in the coordination sphere of rhodium to the corresponding vinylidenes :C=C(R)SiR'3[41, we set out to investigate whether a similar rearrangement proceeds with stannyl-substituted acetylenes, too. We expected that due to the decrease in bond strength along the series C-Si > C-Ge > C-Sn['] a 1,2-SnR3 shift should be less activated than a 1,2-SiR3 shift. However, due to the reduced bond strength and the higher electrophilicity of tetravalent tin, an increased tendency to undergo side reactions was also expected. In this context, we note that Lewis et a1.L61 have recently shown that mono-, oligo-, and polymeric alkynylrhodium(II1) complexes are obtained on treatment of [Rh(PMe3)4]C1 with SnR3-substituted alkynes, one of the driving forces in these processes being the formation of R3SnCl.In the present paper we report that with [RhC1(PiPr3)z], (1) and RC=CSnPh3 as starting materials square-planar vinylidenerhodium(1) complexes bearing a SnPh3 group at the P-carbon atom of the vinylidene ligand can be prepared. They readily react not only with proton sources by C-Sn bond cleavage but also with PhHgCl to give a novel type of Rh-Hg dimetallic products. Vinylidenerhodium Complexes from RC=CSnPh3Since we had found that trimethylsilyl-substituted alkynes are more reactive toward 1 than the SiPh3-substituted we began our studies with alkynes RC=CSnMe3 (R = H, tBu, Ph, C02Me) as substrates. However all attempts to coordinate these alkynes to the [RhC1(PiPr3 A clean reaction occurs by adding triphenylstannyl-substituted alkynes RC=CSnPh3 (R = H, Me, Ph) to a solution of 1 in THF at -50 to -78°C. After slow warming to room temperature, red to violet microcrystalline solids are isolated which according to the spectroscopic data are not the alkyne but the isomeric vinylidene complexes 2a-c. Diagnostic, in particular[2a], are the two signals at low field in the I3C-NMR spectra in the range of 6 = 270-290 and 80-110 which are both split into doublets of triplets due to Rh-C and P-C coupling. The absence of a C=C stretching frequency in the IR spectra at about 1800-1850 cm-' further supports the proposed coordination of a vinylidene instead of an alkyne ligand.[RhC1(PiPrJz], 1

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ChemInform Abstract: TIN‐119 AND PHOSPHORUS‐31 NMR SPECTROSCOPY OF THE 5‐COORDINATE COMPLEXES (RH(SNCLNBR(3‐N))(NORBORNADIENE)(TERTIARY PHOSPHINE)2)

Garralda¹,

García²,

Kretschmer³

et al. 1981

Chemischer Informationsdienst

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¹¹⁹Sn‐ and ³¹P‐NMR. Spectroscopy of the 5‐coordinate complexes [Rh (SnCl_nBr_(3−n)) (norbornadiene) (tertiary phosphine)₂]

Cited by 20 publications

References 29 publications

Halogen Exchange and Scrambling between C−X and M−X‘ Bonds in Copper, Nickel, and Cobalt Complexes of 6,6‘-bis(bromo/ chloromethyl)-2,2‘-bipyridine. Structural, Electrochemical, and Photochemical Studies

Halogen Exchange and Scrambling between C−X and M−X‘ Bonds in Copper, Nickel, and Cobalt Complexes of 6,6‘-bis(bromo/ chloromethyl)-2,2‘-bipyridine. Structural, Electrochemical, and Photochemical Studies

Stannylalkynes as Starting Materials for the Synthesis of Vinylidene Rhodium Complexes and of Heterodimetallic Compounds Containing a Rh—Hg or Rh—Sn Bond

ChemInform Abstract: TIN‐119 AND PHOSPHORUS‐31 NMR SPECTROSCOPY OF THE 5‐COORDINATE COMPLEXES (RH(SNCLNBR(3‐N))(NORBORNADIENE)(TERTIARY PHOSPHINE)2)

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