Li-Cheng Song

Excited-state absorption and optical-limiting properties of organometallic fullerene–C60 derivatives

Singlet excited-state absorption properties and optical limiting behaviors of organochromium and organomolybdenum C60 derivatives (C89H24CrO3P2 and C89H24MoO3P2) were studied by using a double frequency ns/ps Nd:YAG pulse laser system at wavelength of 532 nm and pulse width 21 ps. The experimental results demonstrated that the optical limiting behavior of organochromium C60 derivative is better than both organomolybdenum C60 derivative and fullerene–C60 itself. The experimental results agree well with the singlet excited-state absorption theory.

Preparation and structural characterization of [RSFe2(CO)6]2S. A novel route to FeS cluster compounds containing a sulfur atom coordinated to four metal atoms

Abstract The reaction of monoanions derived from (μ-S2)Fe2(CO)6 and RMgBr (R ue5fb CH3, C2H5, C6H5CH2, p-CH3C6H4, C6H5Cue5fcC) with di-acid chlorides at room temperature unexpectedly produced tetranuclear complexes of general formula [RSFe2(CO)6]2S in high yield. These complexes have been characterized by proton NMR, IR and elemental analysis. A single crystal X-ray study (for R ue5fb C2H5) has unambiguously confirmed the composition and revealed that there is a pseudotetrahedral sulfur atom bridging the four iron atoms and so joins together the two identical [RSFe2(CO)6] fragments. This compound (R ue5fb C2H5) crystallizes in the space group P212121 with a 11.875(2), b 12.920(3), c 17.020(3) A, Z = 4; Dc 1.754 g cm−3. Intensity data of 3550 independent reflections were collected in the range 2° 3σ (I)) being used in the structure refinement. When the reaction was stopped at lower temperature, the diacyl groups were found to have bridged the two monoanions.

Z-scan of excited-state nonlinear materials with reverse saturable absorption

Abstract The nonlinear refraction property of excited-state nonlinear optical materials was studied based on rate-equation theory. The effects of the ratios of excited-state absorption cross section and refrangibility to those of ground state upon their nonlinear refraction properties were analyzed. The nonlinear optical properties of ( m -MeC 6 H 4 ) 5 C 60 H-toluene solution were investigated by using Z -scan method with 8 ns 532 nm laser pulses. The solution was proved to possess strong nonlinear absorption and weak nonlinear refraction.

Synthesis of single and double butterfly iron carbonyl complexes by reactions of [(μ-RSe)(μ-CO)Fe2(CO)6]− anions. Crystal structures of (μ-p-MeC6H4Se)[μ-PhCH2N(H)CS]Fe2(CO)6 and [(μ-PhSe)(μ-MeAs)Fe2(CO)6]2

Abstract The in situ reactions of the [Et3NH]+ and [MgBr]+ salts of [(μ-RSe)(μ-CO)Fe2(CO)6]− (1) anions with PhC(Cl)ue605NPh gave single butterfly complexes (μ-RSe)(μ-PhCue605NPh)Fe2(CO)6 (2, R=Ph; 3, R=p-MeC6H4; 4, R=Et), whereas those of the [Et3NH]+ salts of 1 with R′Nue605Cue605S afforded single butterfly complexes (μ-RSe)[μ-R′N(H)Cue605S]Fe2(CO)6 (5, R=Ph, R′=Ph; 6, R=p-MeC6H4 R′=Ph; 7, R=p-MeC6H4, R′=PhCO; 8, R=p-MeC6H4, R′=PhCH2). Compound 8 could also be prepared by reaction of the [MgBr]+ salt of 1 (R=p-MeC6H4) with PhCH2NCS followed by treatment with CF3CO2H. More interestingly, while the [Et3NH]+ salt of 1 (R=Ph) reacted with Et3OBF4 to give a carbyne ligand-bridged single butterfly complex (μ-PhSe)(μ-EtOC)Fe2(CO)6 (9), reaction of the [Et3NH]+ salt of 1 (R=Ph) with MeAsI2 produced a MeAsue5f8AsMe ligand-bridged double butterfly complex [(μ-PhSe)(μ-MeAs)Fe2(CO)6]2 (10). All the new complexes, 2–10, were characterized by elemental analysis and various spectroscopic methods, for complexes 8 and 10, the structures were also confirmed by X-ray diffraction techniques.

Synthesis and structural characterization of the novel tetrahedral MNiFeS clusters containing functionally substituted cyclopentadienyl ligands (η5-RC5H4(η5-C5H5)MNiFeS(CO)5 (M = Mo, W ; R = CHO, CH3CO, CH3O2C, CH2OH, CH(OH)CH3, (NO2)2C6H3NHN). The crystal molecular structure of (η5-CHOC5H4(η5-C5H5)MoNiFeS(CO)5

Abstract A series of functionally substituted cyclopentadienyl MNiFeS clusters (η5-RC5H4(η5-C5H5)MNiFes(CO)5 (1, M = Mo, R = CHO; 2, M = W, R = CHO; 3, M = Mo, R = CH3CO; 4, M = W, R = CH3CO; 5, M = Mo, R = CH3O2C; 6, M = W , R = CH3O2C) were successfully synthesized by isolobal displacement reactions of corresponding functional cyclopentadienyl MCoFeS clusters η5-RC5H4MCoFeS(CO)8 with nickelocene in THF at reflux. Further treatment of clusters 1–4 with reducing NaBH4 at r.t. in MeOH yielded primary and secondary alcohol cluster derivatives (7, M = Mo, R = CH2OH ; 8, M = W , R = CH2OH; 9, M = Mo, R = CH(OH)CH3 ; 10, M = W, R = CH(OH)CH3), which could react with the alkylating reagent Et3OBF4 to give ether cluster derivatives (11, M = Mo, R = CH(OC2H5)CH3; 12, M = W, R = CH(OC2H5)CH3). Although reactions of clusters 1 and 2 with an aqueous acid solution of 2,4-dinitrophenylhydrazine at r.t. led to almost complete decomposition of the starting clusters, the reactions of clusters 3 and 4 under similar conditions afforded phenylhydrazone cluster derivatives (13, M = Mo, R = 2,4-(NO2)2C6H3NHN ; 14, M = W, R = 2,4-(NO2)2C6H3NHN). All these novel cluster products have been characterized by elemental analysis and spectroscopic techniques, as well as for cluster 1 by X-ray crystallographic study.

Synthesis of group 6 metal triply bonded dimers [η5-RC5H4(CO)2M2 and their reactions with Co2(CO)8. X-ray molecular structure of η5-MeCOC5H4(CO)3MoCo(CO)4

Abstract By thermolysis of metal-metal singly bonded compounds [η5-RC5H4(CO)3M]2 in toluene or diglyme, the corresponding triply bonded dimers [η5-RC5H4(CO)2M]2 (I) (M = Mo, R = MeCO, MeO2C, EtO2C; M = W, R = n-Bu) were produced in 45–94% yields. Further reactions of I (M = Mo, R = MeCO, EtO2C; M = W, R = n-Bu) with Co2(CO)8 in toluene at room temperature gave the heterobimetallic complexes η5-RC5H4 (CO)3Mue5f8Co(CO)4 (II) (M = Mo, R = MeCO, EtO2C; M = W, R = n-Bu) in 43–46% yields. The structures of these seven new compounds have been characterized by elemental analysis, IR, 1H NMR and mass spectroscopy, as well as the structure of II (M = Mo, R = MeCO), which was established by single-crystal X-ray diffraction techniques.

Unexpected metalmetal bond formation in the MHgM (M = Cr, Mo, W) structural unit. Synthesis and characterization of [η5-RC5H4(CO)3M]2Hg complexes (R = H, M = W; R = CH3CO, M = Cr, Mo, W)

Abstract Trimetallic complexes with the general formula of [η 5 -RC 5 H 4 (CO) 3 M] 2 Hg (R = H, M = W. R = CH 3 CO, M = Cr, Mo, W) were prepared from the reactions of MeHgCl with Nη 5 -C 5 H 5 W(CO) 3 ] or with Na[η 5 -CH 3 COC 5 H 4 M(CO) 3 ] (M = Cr, Mo, W) in diglyme. Structures assigned by combustion analysis and spectroscopy were confirmed by X-ray crystal structure determination of one representative complex, [η 5 -C 5 H 5 (CO) 3 W] 2 Hg. This molecule crystallizes in the monoclinic space group C 2/ c with a = 21.119(2), b = 7.067(1), c = 12.033(1) A; β = 91.10(1)°; V = 1795.5 A 3 ; Z = 4. While the Wue5f8Hgue5f8W skeleton possesses a linear configuration, the geometry around each tungsten atom approximates to a square-based pyramid with the cyclopentadienyl ring occupying the apical position.

Unexpected reactions of anionic intermediates [(μ-RS)(μ-Se)Fe2(CO)6]− with SO2Cl2. Synthesis of [(μ-RS)Fe2(CO)6]2(μ4-Se)(R = Ph, Et, nPr, tBu) and crystal structure of [(μ-PhS)Fe2(CO)6]2(μ4-Se)

Abstract The addition of elemental selenium to CO-bridged anions [(μ-RS)(μ-CO)Fe2(CO)6]− gave new selenido-bridged intermediates [(μ-RS)(μ-Se)Fe2(CO)6]−. Treatment of the intermediates in situ with SO2Cl2, afforded unexpected products [(μ- RS ) Fe 2 ( CO ) 6 ] 2 (μ 4 - Se )( R = Ph, Et, n Pr, t Bu ) , among which the structure of the product with R=Ph was confirmed by X-ray crystallography. It crystallized in the monoclinic space group P21/n(#14) with the lattice constants a=8.971(3), b=12.891(8), c=26.955(7) A , β=98.03(2) and Z=4. The structure was refined to an R value of 0.069.

Synthesis of novel quadruply bridged M2Se4 clusters trans/anti and trans/syn-[(η5-RC5H4)2M2(μ-Se)2(μ-SeCH2Ph)2] (M=Mo, W) via an unexpected reaction of MM triply bonded complexes [(η5-RC5H4)2M2(CO)4] with dibenzyl diselenide. Crystal structures of a pair of isomers trans/anti- and trans/syn-[(η5-EtO2CC5H4)2Mo2(μ-Se)2(μ-SeCH2Ph)2]

Abstract The unexpected reaction of triply bonded complexes [(η5-RC5H4)2M2(CO)4] with dibenzyl diselenide (PhCH2)2Se2 in toluene at reflux gave a series of isomeric M2Se4 clusters trans/anti-[(η5-RC5H4)2M2(μ-Se)2(μ-SeCH2Ph)2] (1a, M=Mo, R=MeCO; 2a, Mo, MeO2C; 3a, Mo, EtO2C; 4a, W, MeCO; 5a, W, MeO2C; 6a, W, EtO2C) and trans/syn-[(η5-RC5H4)2M2(μ-Se)2(μ-SeCH2Ph)2] (1b, M=Mo, R=MeCO; 2b, Mo, MeO2C; 3b, Mo, EtO2C; 4b, W, MeCO; 5b, W, MeO2C; 6b, W, EtO2C) in combined 20–41% yields. In addition, the reaction of [(η5-MeO2CC5H4)2W2(CO)4] with (PhCH2)2Se2 in solid state at 90°C also afforded 5a and 5b in a total of 32% yield. The structures of these new clusters were fully characterized by elemental analysis and spectroscopy; those for 3a and 3b were confirmed by single-crystal X-ray diffraction techniques.

Syntheses, spectroscopic characterization and electrochemical properties of organometallic crown ethers containing tetrahedral W2Fe(μ3-S) cluster cores [W2Fe(μ3-S)(CO)7][η5-C5H4CH2(CH2OCH2)nCH2C5H4-η5] (n=1–3). Crystal structures of [W2Fe(μ3-S)(CO)7][η5-C5H4CH2(CH2OCH2)nCH2C5H4-η5] (n=2,3)

Abstract The self-assembly cyclization reactions of the ether chain-bridged dicyclopentadienyl W/Na salts Na2[{W(CO)3}2{η5-C5H4CH2(CH2OCH2)nCH2C5H4-η5}] (Ia–c, n=1–3) with the same chain-bridged dicyclopentadienyl double clusters [WCoFe(μ3-S)(CO)8]2[η5-C5H4CH2(CH2OCH2)nCH2C5H4-η5] (IIa–c, n=1–3) have been shown to give organometallic crown ethers [W2Fe(μ3-S)(CO)7][η5-C5H4CH2 (CH2OCH2)nCH2C5H4-η5] (IIIa–c, n=1–3). While structures of these new W2Fe(μ3-S) cluster crown ethers were fully characterized by elemental analyses, IR, 1H-NMR and FAB-MS spectroscopies, those of IIIb,c were unambiguously confirmed by X-ray diffraction techniques. In the study of possible pathway for the formation of IIIa–c, the new cluster crown ether IIIc and its known Mo analog [Mo2Fe(μ3-S)(CO)7][η5-C5H4CH2(CH2OCH2)3CH2C5H4-η5] (IV) were also found to be formed through self-assembly cyclization reaction of the W/Na salt Na2[{W(CO)3}2{η5-C5H4CH2(CH2OCH2)3CH2C5H4-η5}] and the corresponding Mo-containing double cluster [MoCoFe(μ3-S)(CO)8]2[η5-C5H4CH2(CH2OCH2)3CH2C5H4-η5]. In addition, the electrochemical properties of IIIa–c have been studied by cyclic voltammetric techniques.