199620-14-9Relevant academic research and scientific papers
Transition metal complexes of chromium, molybdenum, tungsten, and manganese containing η1(S)-2,5-dimethylthiophene, benzothiophene, and dibenzothiophene ligands
Reynolds, Michael A.,Guzei, Ilia A.,Logsdon, Bradley C.,Thomas, Leonard M.,Jacobson, Robert A.,Angelici, Robert J.
, p. 4075 - 4081 (1999)
Ultraviolet photolysis of hexanes solutions containing the complexes M(CO)6 (M = Cr, Mo, W) or CpMn(CO)3 (Cp = η5-C5H5) and excess thiophene (T*) (T* = 2,5-dimethylthiophene (2,5-Me2T), benzothiophene (BT), or dibenzothiophene (DBT)) produces the η1(S)-T* complexes (CO)5M(η1(S)-T*) 1-8 or Cp(CO)2Mn(η1(S)-T*) 9-11, respectively. However, when T* = DBT and M = Mo, a mixture of two products results, which includes (CO)5Mo(η1(S)-DBT), 4a, and the π-complex (CO)3Mo(η6-DBT), 4b, as detected by 1H NMR spectroscopy. Only the complexes (CO)5W(η1(S)-DBT) (1), (CO)5Cr(η1(S)-DBT) (5), and Cp(CO)2Mn(η1(S)-DBT) (9) were sufficiently stable (several days) to be isolated and characterized by elemental analyses. Rates of DBT ligand displacement by CO (1 atm) at room temperature decreased in the order 5 > 1 > 9. Single-crystal, X-ray structural determinations are reported for 1, 5, and 9. The tilt angle (θ) of the DBT ligand in these and related complexes is discussed in terms of π-back-bonding to the DBT ligand.
Synthesis and comparison of transition metal complexes of abnormal and normal tetrazolylidenes: A neglected ligand species
Schaper, Lars-Arne,Wei, Xuhui,Altmann, Philipp J.,Oefele, Karl,Poethig, Alexander,Drees, Markus,Mink, Janos,Herdtweck, Eberhardt,Bechlars, Bettina,Herrmann, Wolfgang A.,Kuehn, Fritz E.
, p. 7031 - 7044 (2013/07/26)
To date, only few examples of tetrazolylidene carbenes coordinated to transition metal complexes have been described. A direct comparison of normal tetrazolylidenes (1,4-substitution pattern) and abnormal tetrazolylidenes (also referred to as mesoionic carbenes ; 1,3-substitution pattern) has not been performed at all. In this work, we describe coordination of both ligand types to a row of transition metals. For example, the first examples of tetrazolylidene Mo, Ag, or Ir complexes have been isolated and fully characterized. The mesoionic tetrazolylidene Ag compound 2d is shown to be a viable carbene transfer reagent. By means of NMR, IR, and Raman spectroscopy, as well as X-ray crystallography and computational results, the pronounced differences between the two ligand substitution patterns are highlighted. It is shown that simply changing the position of a methyl group from N3 to N4 in the heterocycle can cause enormous differences in ligand characteristics.
Chromium-manganese selenide carbonyl complexes: Paramagnetic clusters and relevance to C = O activation of acetone
Shieh, Minghuey,Lin, Chien-Nan,Miu, Chia-Yeh,Hsu, Miao-Hsing,Pan, Yi-Wen,Ho, Li-Fang
, p. 8056 - 8066 (2011/01/10)
The paramagnetic even-electron cluster, [Et4N] 2[Se2Cr3(CO)10], was found to react readily with Mn(CO)5Br in acetone to produce two unprecedented mixed chromium-manganese selenide carbonyl complexes, [Et4N][Me 2CSe2{Mn(CO)4}{Cr(CO)5} 2] ([Et4N][1]) and [Et4N]2[Se 2Mn3(CO)10{Cr(CO)5}2] ([Et4N]2[2]). X-ray crystallographic analysis showed that anion 1 consisted of two Se-Cr(CO)5 moieties, which were further bridged by one isopropylene group and one Mn(CO)4 moiety. The dianionic cluster 2 was shown to display a Se2Mn3 square-pyramidal core with each Se atom externally coordinated by one Cr(CO)5 group. The formation of complex 1, presumably via C=O activation of acetone, was further facilitated by acidification of the reaction of [Et4N]2[Se2Cr3(CO)10] with Mn(CO)5Br in acetone. Complex 1 readily transformed into 2 upon treatment with Mn2(CO)10 in a KOH/MeOH/MeCN solution. Cluster 2 was a 51-electron species, which readily converted to the known 49-electron cluster [Se2Mn3(CO)9]2- upon heating and bubbling with CO. Magnetic studies of the even-electron cluster, [Et4N]2[Se2Cr3(CO) 10], and the odd-electron species, [Et4N]2[2] and [PPN]2[Se2Mn3(CO)9], were determined by the SQUID measurement to have 2, 3, and 1 unpaired electrons, respectively. In addition, the nature and formation of complexes 1 and 2 are discussed, and the magnetic properties and electrochemistry of [Se 2Cr3(CO)10]2-, 2, and [Se 2Mn3(CO)9]2- were further studied and elucidated by molecular orbital calculations at the PW91 level of density functional theory.
Hydroquinoid chromium complexes bearing an acyclic conjugated bridge: Chromium-templated synthesis, molecular structure, and haptotropic metal migration
Hegele, Peter,Santhamma, Bindu,Schnakenburg, Gregor,Froehlich, Roland,Kataeva, Olga,Nieger, Martin,Kotsis, Konstantinos,Neese, Frank,Doetz, Karl Heinz
, p. 6172 - 6185 (2011/02/16)
The naphthohydroquinoid tricarbonyl chromium complexes 3 and 6, bearing a styryl or phenylazo moiety, have been synthesized and studied for the haptotropic metal migration along the extended π-system. Quantum chemical calculations suggested a feasible stepwise rearrangement of the Cr(CO) 3 fragment from the hydroquinoid to the other terminal phenyl ring for the azo- rather than for the ethene-bridged system. An experimental and kinetic study of the ethene-bridged complex 3 revealed a haptotropic metal shift onto the adjacent naphthalene ring to give isomer 7 and suggested a competing intermolecular decomplexation-recomplexation pathway for the coordination of the terminal phenyl ring, affording bismetalated complexes 8 and 9. Attempts of a controlled metal migration in the azo complex analogue 6 under similar conditions were unsuccessful and resulted in partial decomposition.
Diversity and design of metal-based carbon monoxide-releasing molecules (CO-RMs) in aqueous systems: Revealing the essential trends
Zhang, Wei-Qiang,Atkin, Anthony J.,Thatcher, Robert J.,Whitwood, Adrian C.,Fairlamb, Ian J. S.,Lynam, Jason M.
, p. 4351 - 4358 (2009/10/17)
The CO-releasing ability of a diverse library of primary metal carbonyl complexes has been assessed using a deoxymyoglobin-carbonmonoxymyglobin assay. A wide spectrum of rates for the CO-release process was observed in aqueous systems. For octahedral dsu
Unusually slow photodissociation of CO from (η6-C 6H6)Cr(CO)3 (M= Cr or Mo): A time-resolved Infrared, Matrix Isolation, and DFT investigation
Alamiry, Mohammed A. H.,Boyle, Nicola M.,Brookes, Christopher M.,George, Michael W.,Conor, Long,Portius, Peter,Pryce, Mary T.,Ronayne, Kate L.,Sun, Xue-Zhong,Towrie, Michael,Khuong, Q. Vuong
, p. 1461 - 1468 (2009/07/18)
The photochemistry of η6-C6H6)M(CO) 3 (M = Cr or Mo) is described. Photolysis with λexc. > 300 nm of (η6-C6H6)Cr(CO)3 in low-temperature matrixes containing CO produce
Borylene-based direct functionalization of organic substrates: Synthesis, characterization, and photophysical properties of novel π-conjugated borirenes
Braunschweig, Holger,Herbst, Thomas,Rais, Daniela,Ghosh, Sundargopal,Kupfer, Thomas,Radacki, Krzysztof,Crawford, Andrew G.,Ward, Richard M.,Marder, Todd B.,Fernandez, Israel,Frenking, Gernot
, p. 8989 - 8999 (2009/12/04)
Room temperature photolysis of aminoborylene complexes, [(CO) 5MdBdN(SiMe3)2] (1: M = Cr, 2: Mo) in the presence of a series of alkynes and diynes, 1,2-bis(4-methoxyphenyl)ethyne, 1,2-bis(4-(trifluoromethyl)phenyl)ethyne,
Effect of temperature on N-ethylcarbazole chromium tricarbonyl complex studied by two-dimensional infrared correlation spectroscopy
Shen, Yi,Wu, Peiyi
, p. 72 - 76 (2009/02/04)
Temperature-dependent variation of N-ethylcarbazole chromium tricarbonyl complex by itself without the solid support has been studied by carefully examining their IR spectra with the aid of two-dimensional correlation analysis. Two obvious stages have been observed during the heating process. In the first stage, the crystalline ECzC undergoes a slow process to change into the amorphous form due to the strong interactions of the hydrogen bonding. In the second stage, ECzC gradually decomposes, which results in the formation of Cr(CO)6. The results suggest that the interaction between the organometallics and its solid support may not have direct influence to the final product generated under the thermal treatment.
A laser flash photolysis, matrix isolation, and DFT investigation of (η6-C6H5Y)Cr(CO)3 (Y = NH2, OCH3, H, CHO, or CO2CH3)
Alamiry, Mohammed A.H.,Brennan, Peter,Long, Conor,Pryce, Mary T.
, p. 2907 - 2914 (2008/12/21)
The quantum yield for arene displacement from (η6-C6H5Y)Cr(CO)3 was measured in 1,1,2-trifluorotrichloroethane (Y = NH2, OCH3, H, CHO, or CO2CH3). Values of 0.24, 0.27, 0.15, 0.17, and 0.32 were obtained respectively (λexc. = 355 nm). These values are significantly higher than those measured for photoinduced arene loss in hydrocarbon solvents using the same excitation wavelength. Laser flash photolysis of (η6-C6H5Y)Cr(CO)3 in 1,1,2-trifluorotrichloroethane (λexc. = 355 nm) resulted in the rapid formation (6. Matrix isolation experiments on (η6-C6H5Y)Cr(CO)3 (Y = H or CHO) at 12 K in CH4 or CO-doped CH4 matrixes using monochromatic irradiation confirmed the presence of two discrete excited states, one leading to CO-loss and the other to arene-loss. The results correlate with the calculated electron drift in the excited state derived from density functional theory and time dependent density functional theory calculations.
Photoinduced Se-C insertion following photolysis of (η5- C4H4Se)Cr(CO)3. A picosecond and nanosecond time-resolved infrared, matrix isolation, and DFT investigation
Brennan, Peter,George, Michael W.,Jina, Omar S.,Long, Conor,McKenna, Jennifer,Pryce, Mary T.,Sun, Xue-Zhong,Vuong, Khuong Q.
, p. 3671 - 3680 (2009/02/05)
The photochemistry of (η5;-C4H 4Se)Cr(CO)3 was investigated by matrix isolation, time-resolved infrared spectroscopy, and steady-state photochemical methods. Density functional theory (DFT) was used to assist in the identification of the photoproducts. Irradiation (λexc= 406 nm) of (η5-C4H4Se)Cr(CO)3 in either an Ar or CH4 matrix at 20 K produced the selenophene ring-opened insertion product (C,Se-C4H4Se)Cr(CO)3. Further irradiation of this matrix produced the CO-loss species (C,Se-C 4H4Se)Cr(CO)2. Pulsed irradiation at 400 nm produced the CO-loss species (η5-C4H 4Se)Cr(CO)2(S) in n-heptane (S) along with the insertion products (C,Se-C4H4Se)Cr(CO)3 and (C,Se-C 4H4Se)Cr(CO)2, both of which may have triplet character. Time-resolved measurements on the microsecond time scale confirmed that the CO-loss species (η5-C4H4Se)Cr(CO) 2(S) reacts with CO (k2 = 5.8 × 106 dm3 mol-1 s-1 at 298 K), while (C,Se-C4H 4Se)Cr(CO)3 and (C,Se-C4H4Se)Cr(CO) 2 do not react on this time scale. DFT calculations provide an explanation of the stability of the triplet (C,Se-C4H 4Se)Cr(CO)3 species in terms of a chromaselanabenzene structure, which is consistent with previously observed metal insertion into coordinated selenophene ligands.
