Synthesis, Redox Reactivity, and X-ray Diffraction Structures of the Rhenium Carbonyl Complexes fac-ReBr(CO)3(bma) and [fac-ReBr(CO)3(bma)][Cp2Co]. Structural Consequences of Electron Accession in fac-ReBr(CO)3(bma)

1995 ◽  
Vol 14 (5) ◽  
pp. 2387-2394 ◽  
Author(s):  
Kaiyuan Yang ◽  
Simon G. Bott ◽  
Michael G. Richmond

2005 ◽  
Vol 83 (6-7) ◽  
pp. 1017-1024
Author(s):  
Giuseppe D'Alfonso ◽  
Claudia Dragonetti ◽  
Simona Galli ◽  
Elena Lucenti ◽  
Piero Macchi ◽  
...  

Reaction of Me3SiONa with [Re(CO)5Cl] affords the new complex Na[Re2(CO)6(µ-OSiMe3)3], which could be generated via formation of [Re(CO)5OSiMe3] followed by immediate reaction with Me3SiO–. Substitution of some CO ligands by phosphines significantly decreases the electrophilicity of the Re(I) center, and therefore hinders further attack by Me3SiO–. Thus, fac-[Re(CO)3(Ph2PCH2CH2PPh2)OTf] (OTf is the triflate anion) reacts with Me3SiONa to give fac-[Re(CO)3(Ph2PCH2CH2PPh2)OSiMe3], a molecular model of silica anchored [Re(CO)5OSi≡]. However, substitution of only one CO by triphenylphosphine is not enough to avoid the formation of [Re2(CO)6(µ-OSiMe3)3]–. While fac-[Re(CO)3(Ph2PCH2CH2PPh2)OSiMe3] is stable towards hydrolysis, [Re2(CO)6(µ-OSiMe3)3]– is readily hydrolyzed to [Re2(CO)6(µ-OH)(µ-OSiMe3)2]–, a molecular model of silica anchored [Re2(CO)6(µ-OH)(µ-OSi≡)2]–, whose structure has been determined by single crystal X-ray diffraction. Key words: surface organometallic chemistry, rhenium, silica, silanolate, molecular model.



1980 ◽  
Vol 33 (11) ◽  
pp. 2369 ◽  
Author(s):  
E Horn ◽  
MR Snow

The complexes Re(CO)5ClO4, Re(CO)5PO2F2, L2(CO)3Re(OClO3) and L2(CO)3Re(PO2F2), where L2 = 2,2?-bipyridyl (bpy), have been synthesized by bromide abstraction reactions from the respective rhenium carbonyl bromide precursors. The complexes were characterized by infrared and mass spectroscopy. The crystal structure of (bpy)(CO)3Re(PO2F2) has been determined from X-ray diffraction data by the heavy-atom technique. The crystals are triclinic, space group Pī with a 8.620(3), b 15.912(5), c 6.466(3) Ǻ, α 102.08(8), β 83.29(8), γ 95.08(4) and Z 2. The structure has been refined by full-matrix least-squares from 2829 reflections to R = 0.084, Rw = 0.088. The coordination geometry about rhenium is that of a distorted octahedron. Difluorophosphate coordinates to the metal centre by one of its oxygen atoms. Formation of the difluorophosphate by hydrolysis of hexafluorophosphate was shown by 31P n.m.r. spectra.



1998 ◽  
Vol 272 (1-2) ◽  
pp. 267-273 ◽  
Author(s):  
Andrea Marchi ◽  
Lorenza Marvelli ◽  
Roberto Rossi ◽  
Valerio Bertolasi ◽  
Valeria Ferretti


Author(s):  
Reza Kia ◽  
Azadeh Kalaghchi

A series of new chlorido-tricarbonylrhenium(I) complexes bearing alkyl-substituted diazabutadiene (DAB) ligands, namely N,N′-bis(2,4-dimethylbenzene)-1,4-diazabutadiene (L1), N,N′-bis(2,4-dimethylbenzene)-2,3-dimethyl-1,4-diazabutadiene (L2), N,N′-bis(2,4,6-trimethylbenzene)-2,3-dimethyl-1,4-diazabutadiene (L3) and N,N′-bis(2,6-diisopropylbenzene)-1,4-diazabutadiene (L4), were synthesized and investigated. The crystal structures have been fully characterized by X-ray diffraction and spectroscopic methods. Density functional theory, natural bond orbital and non-covalent interaction index methods have been used to study the optimized geometry in the gas phase and intra- and intermolecular interactions in the complexes, respectively. The most important studied interactions in these metal carbonyl complexes are n→π*, n→σ* and π→π*. Among complexes 1–4, only 2 shows interesting intermolecular n→π* interactions due to lp(C[triple-bond]O)...π* and lp(Cl)...π* (lp = lone pair) contacts.



2001 ◽  
Vol 66 (2) ◽  
pp. 382-396 ◽  
Author(s):  
Jan Čermák ◽  
Kateřina Auerová ◽  
Huong Thi Thu Nguyen ◽  
Vratislav Blechta ◽  
Pavel Vojtíšek ◽  
...  

Mixtures of isomers of (perfluoroalkyl)tetramethylcyclopenta-1,3-dienes (CH3)4C5H(CF2)nCF3 (n = 3, 5, 7, 9) were synthesized as precursors of new cyclopentadienyl ligands for organotransition metal catalysis in fluorous biphase media and characterized by combination of GC-MS and 13C NMR spectroscopy. Rhodium(III) chloro complexes [Rh{(CH3)4C5(CF2)nCF3}Cl2]2 and rhodium(I) carbonyl complexes [Rh{(CH3)4C5(CF2)nCF3}(CO)2] were prepared from the cyclopentadienes and molecular structure of [Rh{(CH3)4C5(CF2)5CF3}Cl2]2 was determined by X-ray diffraction. The ligands are electronically close to the unsubstituted cyclopentadienyl as shown by values of carbonyl stretching frequencies in the carbonyl complexes. Neither carbonyl frequencies nor NMR chemical shifts of the complexes are substantially affected by the length of the perfluoroalkyl chain.



2000 ◽  
Vol 55 (8) ◽  
pp. 707-717 ◽  
Author(s):  
Hans-Friedrich Klein ◽  
Xiaoyan Li ◽  
Ulrich Flörke ◽  
Hans-Jürgen Haupt

Abstract Formal insertion of phenylethyne into Co-H functions of mer-octahedral acyl(enolato)-cobalt(III) hydrides 1-3 proceeds under ambient conditions affording η1-vinylcobalt(III) compounds where the dianionic acyl(enolato) ligands are derived from 2-formyl-4-phenyl-cyclohexanone (4), 1-formyl-cyclohexan-2-one (5), and 3-hydroxo-2,3-diphenyl-propenal (6). Dissociation and association of trimethylphosphane results in a reversible transformation of penta-coordinate complexes 4 -6 into hexa-coordinate ones 7 -9, respectively, involving different tautomeric vinyl species. In toluene solution 9 rearranges by reductive C,C coupling into a 5,6-η2-olefin(enolato)cobalt(I) complex 10. Trimethylsilylethyne undergoes a hydrolytic desilylation reaction which is followed by reductive C,C-coupling reactions of acyl and vinyl functions selectively producing chelating η1-enolato-5,6-η2-olefin ligands in cobalt(I) com ­ pounds 13 -16 where the (ax,eq)chelating ligands are derived from 1-formyl-cyclohexan-2-one (13), 3-hydroxo-2,3-diphenyl-propenal (14), 2-formyl-α-tetralone (15), and 2-formyl-4-tert-butyl-cyclohexanone (16). An axial position of the enolato-O donor in the trigonal bipyramidal configuration of complex 15 has been confirmed by X-ray diffraction analysis. With 1,4-bis(trimethylsilyl)buta-diyne 1,2-addition in cobalt(III) hydrides 2, 3, 11 (as deriverd from 2-formyl-α-tetralone), and 12 (as derived from 2-formyl-4-tert-butyl-cyclohexanone) produces 2-metalated vinyl groups in compounds 17 -20. Dissociation of trimethylphosphane from 17 and 19 does not activate C,C coupling at the cobalt(III) centre of penta-coordinate 21 and 22. Steric congestion in compounds 17, 18, and 20 favours exchange of trimethylphosphine for carbon monoxide affording the first octahedral carbonyl complexes of cobalt (d6) (23 -25). In the crystal and in solution a meridional configuration is adopted by complex 23 with the CO group in a position opposite to the acyl function.



2000 ◽  
Vol 65 (12) ◽  
pp. 1897-1910 ◽  
Author(s):  
Lenka Lukešová ◽  
Jiří Ludvík ◽  
Ivana Císařová ◽  
Petr Štěpnička

A series of complexes [M(CO)5(Hdpf-κP)], where M = Cr (1), Mo (2) and W (3), and Hdpf is 1'-(diphenylphosphanyl)ferrocenecarboxylic acid, was obtained by thermally-induced (2) or photochemically-assisted (1, 3) displacement of carbon monoxide with Hdpf from the corresponding hexacarbonyl complexes. The complexes were characterized by NMR, UV-VIS and IR spectroscopies and further studied by cyclic voltammetry. The solid-state structure of complex 1 has been determined by single-crystal X-ray diffraction.



2002 ◽  
Vol 656 (1-2) ◽  
pp. 1-10 ◽  
Author(s):  
Rosa Carballo ◽  
José S Casas ◽  
Emilia Garcı́a-Martı́nez ◽  
Gumersindo Pereiras-Gabián ◽  
Agustı́n Sánchez ◽  
...  


Author(s):  
Gabrielle Schanne ◽  
Lucas Henry ◽  
How Chee Ong ◽  
andrea somogyi ◽  
Kadda Medjoubi ◽  
...  

Synchrotron Radiation X-ray Fluorescence (SXRF) imaging is a powerful technique for the visualization of metal complexes in biological systems. However, due to the lack of an endogenous elemental signature for...



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