14729-20-5Relevant academic research and scientific papers
Unexpected formation of a weak metal-metal bond: Synthesis, electronic properties, and second-order NLO responses of push-pull late-early heteronuclear bimetallic complexes with W(CO)3(1,10-phenanthroline) acting as a donor ligand
Pizzotti, Maddalena,Ugo, Renato,Dragonetti, Claudia,Annoni, Elisabetta,Demartin,Mussini
, p. 4001 - 4011 (2008/10/08)
In attempts to bridge the complex [W(CO)3(phen)(pyz)] (phen = 1,10-phenanthroline; pyz = pyrazine) to acceptor centers, either soft centers such as cis-M(CO)2CL (M = Rh(I), Ir(I)) and fac-M(CO)3Cl2 (M = Ru(II), Os(II)) or hard centers such as BF3, the pyrazine ligand is lost, while the fragment W(CO)3(phen) behaves as a σ-donor base with the unexpected formation of heteronuclear early-late bimetallic compounds with a weak metal-metal bond, as confirmed by the easy substitution of W(CO)3(phen) by soft ligands (PPh3, CO, pyridine). The X-ray structures of [(CO)3(phen)W-cis-Ir(CO)2Cl] and [(CO)3(phen)W-fac-Os(CO)3Cl2] confirm a single metal-metal bond with an halogen bridging asymmetrically the two metallic moieties and with the tungsten atom achieving a distorted (6 + 1) octahedral coordination. All the heteronuclear bimetallic complexes investigated show in their electronic spectra a new solvatochromic absorption band at around 385-450 nm in addition to the MLCT (W→π*phen) absorption band typical of [W(CO)3(phen)L] complexes (L = CO, pyz, CH3CN) and an increased, in comparison to [W(CO)4(phen)], negative nonlinear (NLO) second-order emission working with the EFISH technique with an incident wavelength of 1.907 μm. The increase is due to an additional negative contribution of the new absorption band at around 385-450 nm, as shown by a solvatochromic investigation.
Four-coordinate group-14 elements in the formal oxidation state of zero - Syntheses, structures, and dynamics of [{(CO)5Cr}2Sn(L2)] and related species
Kircher, Peter,Huttner, Gottfried,Heinze, Katja,Schiemenz, Berthold,Zsolnai, Laszlo,Buechner, Michael,Driess, Alexander
, p. 703 - 720 (2007/10/03)
The sodium salts Na2[{(CO)5M}2EX2] (M = Cr, Mo, W; E = Ge, Sn, Pb; X = Cl, I, OOCCH3) react with 2,2′-bipyridine (bipy) to form neutral compounds [{(CO)5M}2E(bipy)] (E = Sn: 1a-1c; E = Ge: 3a; E = Pb: 4). 1,10-Phenanthroline (phen) analogues of compounds 1a-1c and 3a [{(CO)5M}2E(phen)] (E = Sn: 1d-1f, E = Ge: 3b) are as well accessible. The 2,2′-bipyridine ligand in 1 may be formally replaced by two pyridine (py) ligands resulting in [{(CO)5M}2Sn(py)2] (1g: M = Cr, 1h: M = W). The bis-bidentate ligand 2,2′-bipyrimidine (bpmd) is found to coordinate just one [{(CO)5M}2Sn] entity in [{(CO)5M}2Sn(bpmd)] (2b: M = Cr, 2c: M = W). The biimidazolato (biim) ligand binds two [{(CO)5Cr}2Sn] moieties in [{(CO)5Cr}2Sn(biim)Sn{Cr(CO)5} 2]2-, 2a. It is shown by 1H-NMR that the pyrimidine entities in these compounds (2b, 2c) are able to rotate by a full 180° turnaround with respect to one another. This process must involve complete de-coordination of at least one of the two nitrogen donors in again at least one of the chelate cycles, the activation energy for this process being around 60 kJ/ mol. By 119Sn-NMR spectroscopy of almost all of the tin compounds described it is shown that equilibria between [{(CO)5M}2Sn(L2)] and [{(CO)5M}2Sn(L)] + L exist in all cases. From the temperature dependence of the δ values it is concluded that the activation barriers for this association/ dissociation process is below 10 kJ/mol. The structures of all new compounds are documented by X-ray analyses and all compounds are characterized by the usual analytical and spectroscopical techniques.
Oxidative addition of disulfides to the complex W(CO)3(phen)(EtCN). Synthesis, structure, and reactivity of W(CO)2(phen)(SR)2 (R = Ph, Me, CH2Ph, tBu; phen = 1,10-phenanthroline) coordinatively unsaturated complexes of tungsten(II) that reversibly bind CO and other ligands
Lang, Russell F.,Ju, Telvin D.,Kiss, Gabor,Hoff, Carl D.,Bryan, Jeffrey C.,Kubas, Gregory J.
, p. 3899 - 3907 (2008/10/08)
The complex W(CO)3(phen)(EtCN) undergoes oxidative addition with disulfides forming the formally 16-electron complexes W(CO)2(phen)(SR)2 (R = Ph, tBu, Me, benzyl). The reactions proceed through intermediates identified spectroscopically as the coordinated disulfide complexes. The rate of oxidative addition of coordinated disulfides is in the order tBuSSBut ? MeSSMe 2SSCH2Ph 2(phen)(SR)2 undergo ligand addition, ligand substitution, and thiol/thiolate exchange reactions. Variable-temperature equilibrium studies yielded thermodynamic parameters for binding of CO to W(CO)2(phen)(SR)2: R = Ph, ΔH = -7.2 ± 0.5 kcal/mol, ΔS = -29 ± 3.5 cal/(mol deg); R = tBu, ΔH = -9.5 ± 0.5 kcal/mol, ΔS = -41 ± 3.5 cal/(mol deg). Reaction with trimethylphosphine yields an equilibrium mixture of the 18-electron adduct W(CO)2(phen)(PMe3)(SPh)2 as well as the 16-electron monocarbonyl complex W(CO)(phen)(PMe3)(SPh)2. Addition of trimethyl phosphite yields only W(CO)(phen)(P(OMe)3)(SPh)2. Pyridine, propionitrile, hydrogen, and THFdo not bind to the W(II) complexes. Reaction of W(CO)2(phen)(StBu)2 with 1 equiv of thiophenol yields W(CO)2(phen)(StBu)(SPh), which reacts with additional thiophenol to yield W(CO)2(phen)(SPh)2. Reaction with excess hydrogen sulfide yields W(CO)2(phen)(SH)2, which reacts further with thiophenol to yield W(CO)2(phen)(SPh)2. Crystal structures are reported for W(CO)2(phen)(SPh)2 and W(CO)(phen)(P(OMe)3)(SPh)2.
