Comparison of(η~6-Fluoroarene)tricarbonylchromium Complexes with Their Chloro-analogs in Radical Aromatic Substitutions

Reactions of fluoroarene-Cr(CO)_3 complexes with SmI_2 andcarbonyl compounds in THF/HMPA at-40— -60℃ affordedthe corresponding radical aromatic substitution products in highyield. Compared to the corresponding chloroarene-Cr.(CO)_3complexes, fluoroarene-Cr(CO)_3 complexes showed a higher ef-ficiency and slightly lower regioselectivity.     

STUDIES ON ORGANO-MOLYBDENUM AND TUNGSTEN COMPOUNDS(Ⅲ)——CATALYTIC POLYMERIZATION OF ACETYLENE BY M-O-C BOND-CONTAINING COMPLEXES OF Mo AND W

Catalytic polymerization of acetylene in the presence of n5-C5H5-M-(CO)3 R (M=Mo,W;R=CH3-,C2H5-) has been studied.The results show that these complexes possess catalytic activities for the polymerization and copolymerization of monosubstituted acetylene.The catalytic mechanism has been preliminarily discussed.It is suggested that the active species be metal-car-bene.In our previous publications we reported the synthesis of some new Fischer's molybdenum and tungsten-carbene complexes and catalytic activity for alkyne polymerization.The results show that the activity of Fischer's molybdenum-carbene is higher than that of tungsten.The catalytic polymerization of alkyne by M-σ-c bond-containing complexes of molybdenum and tungsten has not been reported yet in literature.Therefore,four M-σ-C bondontaining complexes of molybdenum and tungsten were synthesized by using the method reported in the literature,and catalyst polymerization of alkyne by these complexes was examined.     

Synthesis and CD Spectra of Chiral Molybdenum-fullerenyl Complexes with Pineno-bipyridine Ligands

The synthesis and characterization of two chiral fullerene complexes( )4in^CD-[Mo(η^2-C60)(CO)3(L^RR)]1 and (-)430^CD-[Mo(η^2-C60)(CO3)(L^SS)2 were described,the CD spectra of 1 and 2 in the visible range show Cotton effects,which are approximately of mirror image,indicating that the appended pineno-groups with opposite chirality in bipyridines can perturb the fullcrene chromophores through the molybdenum centers and lead to induced CD effects.     

SYNTHESIS AND STRUCTURAL STUDIES ON UNSYMMETRICAL TYPE OF DI-(μ-ALKYLTHIO)HEXACARBONYLDIIRON COMPLEXES CONTAINING CYCLOHEXYL OR BENZYL GROUP

Twenty new Fe-S cluster complexes having a general formula (μ-RS) (μ-R'S)-Fe_2(CO)_6 were synthe-sized through reduction of -S_2Fe_2(CO)_6 with RMgC1, followed by in situ nucleophilic substitution of RXwith the intermediates (μ-RS)(μ-C1MgS)Fe_2(CO)_6. Besides the data of m.p., C/H, IR and ~1H NMRdetermined, the conformers of these complexes and the ratios of the conformers have been discussed ac-cording to the chemical shifts and integrated values of methyl, methylene and methyne groups attachedto the sulfur atoms in the complexes.     

Syntheses and Characterization of Two Diiron Dithiolate Complexes with Electron-withdrawing and Electron-donating Substitution

Two diiron dithiolate complexes [Fe_2(CO)_6(1,8-S_2-2-CH_2OOCPhC_(10)H_5)] 1 and[Fe_2(CO)_6(1,8-S_2-2-CH_2OOCPh-4-NO_2C_(10)H_5)]2 were synthesized in high yield. The complexes have been confirmed by single-crystal X-ray diffraction and characterized by IR, UV-Vis, ~1H NMR spectroscopy and cyclic voltammetry. They contain a butterfly Fe_2S_2 core with the Fe1–Fe_2 distances of 2.5237(7) ? in 1 and 2.5125(12) ? in 2, falling in the normal range of Fe–Fe bond length(2.49 ~ 2.57 ?). The cyclic voltammetry has been used to investigate the electrochemical properties and the electrocatalytic proton reduction for 1 and 2. The complexes display reduction peaks at –1.074 V, –1.535 V(1) and –0.869 V, –1.247 V(2) vs. Fc/Fc+, respectively. With using p-Ts OH acid of different concentration, the reduction peak of complex 2 grows non-linear; on the contrary, that of complex 1 is linear with the addition of the acid. Cyclic voltammetry revealed the two complexes are good catalysts in the CH_3CN/NBu_4PF_6 solution.     

Theoretical Studies on the Intermolecular Interactions of Aza-calix[2]arene[2]-triazines with RDX

Six fully optimized structures of the aza-calix[2]arene[2]-triazines/RDX supramo-lecular complexes have been obtained at the DFT-B3LYP/6-311++G** level,and the corresponding intermolecular interactions have been investigated using the B3LYP,mPWPW91 and MP2 methods at the 6-311++G** level,respectively.The natural bond orbital(NBO) and atoms in molecules(AIM) analyses have been performed to reveal the origin of interactions.To our interest,the result indicates that the strongest interaction is up to -22.34 kJ/mol after basis set superposition error(BSSE) and zero point energy(ZPE) correction at the MP2/6-311++G** level.Furthermore,the intermolecular interactions between aza-calix[2]arene[2]-triazines with the substituted amidos and RDX are stronger than those of other complexes.Thus,the complexes with amidos can be used as the candidates to increase the stability of explosive and eliminate the explosive wastewater.     

Synthesis and Thermal Rearrangement of Tetramethyldisilane-bridged Bis(cyclopentadienyl) Diiron Complexes with Bis(phosphine)Substitution

Photolysis of [Me2SiSiMe2)[C5H4Fe(CO2)]2with a series of bis(phosphine)ligands Ph2P(CH2)n PPh2(n=1-4) leads to the formation of the corresponding diiron complexes with intramolecular and intermolecular bis(phosphine) substitution.When these complexes were heated in refluxing xylene.only in the complexes with intermolecular bis(phosphine )substitution the thermal rearrangement reaction occurred.     

POLYKETONE FROM CO AND STYRENE: A USEFUL COPOLYMER CATALYZED BY A HIGHLY ACTIVE AND STABLE PALLADIUM CATALYST WITH 5-NITRO-1,10-PHENANTHROLINE LIGAND

A novel coordinated complex [(5-nitrophen)Pd(CF3CO2)2] (5-nitrophen = 5-nitro-l,10-phenanthroline) was first synthesized. By using XPS, IR, and 1H-NMR, its coordination unit was studied in comparison with those of complexes [(N- N)Pd(CH3CO2)2] and [(N - N)Pd(CF3CO2)2]. The H2,9 proton signals of 1H-NMR spectra of the complexes are excellent probes to monitor the evolution of the environment of the palladium atom. The state of anionic coordination was confirmed by the presence of IR absorption peaks of COO in complexes ([(N N)Pd(CH3CO2)2] and [(NN)Pd(CF3CO2)2]). Bonding energies of N1s and Pd3d5 obtained from XPS data testified to the strength of the N-Pd coordinating bond. The conclusion can be drawn by analyzing these data from IR, XPS and 1H-NMR that it is the unsymmetrical substitution of the 1,10-phenanthroline (phen) that makes the [(5-nitrophen)Pd(CF3CO2)2] more active.Experimental results showed that [(5-nitrophen)Pd(CF3CO2)2] exhibits much higher activity than [(bipy)Pd(CF3CO2)2] (1, l‘-bipyridine = bipy) and [(phen)Pd(CF3CO2)2] under the same conditions.     

Density Functional Theory Studies on the Intermolecular Interactions of Five Aza-calix [6] arene Host with HMX

Five fully optimized structures of complexes between aza-calix[6]arene host monomers(Ma～Me) and complexes(a～e) have been obtained at the B3LYP/6-31G(d) level.Natural bond orbital(NBO) analysis was performed to reveal the origin of the interaction.The intermolecular interaction energy was evaluated with basis set superposition error correction(BSSE) and zero point energy correction(ZPEC).The B3LYP/6-31G(d) calculations on the five complexes have shown that the greatest interaction(-13.98 kJ/mol) is found in the complex between HMX and hexa-aza-calix[3]-p-tri-arene[3]-2-amido-1,3,5-tri-azine.The results have indicated that intermolecular interaction energies of aza-calix[6]arenes with substituted group are stronger than those without substituted group,and those with amido are greater than with nitryl.Thus,hexa-azacalix[3]-p-tri-arene[3]-2-amido-1,3,5-tri-azine is rather equal to eliminate HMX from explosive waste water.     

A STUDY ON THE INTERACTION BETWEEN CH_3OH AND H_2CO MOLECULES IN TERMS OF THE PROPERTIES OF CHARGE DENSITY DISTRIBUTIONS

Two possible complexes formed by the interaction of CH_3OH and H_2CO,one hydrogen-bonded(Ⅰ)and one donor-acceptor complex(Ⅱ),have been reported in the previous paper.Based on theab initio 6-31G basis set calculations,the properties of the charge density for the complexeshave beenanalyzed using the theory of atoms in molecules.The nature of the complex formation has beendiscussed in terms of the properties of the charge density distributions.     

Reactive E=C(p‐p)π‐Systems. 55. [1] Ligand Properties of 1‐Trifluoromethyl‐2‐diethylamino‐2‐fluoro‐1‐arsaethene,F3CAs=C(F)NEt2

Due to the mesomeric interaction of the nitrogen lone pair with the As=C double bond, the perfluoroarsapropene derivative F₃CAs=C(F)NEt₂ ( 1 ) is sufficiently stable to serve as a ligand in transition metal carbonyl complexes. 1 was coordinated to chromium by reaction with the photochemically generated labile complex Cr(CO)₅(THF), yielding the monosubstituted pentacarbonyl derivative Cr(CO)₅[F₃CAs=C(F)NEt₂] ( 2 ). Already at room temperature, this is slowly transformed into the binuclear complex [F₃CAs=C(F)NEt₂][Cr(CO)₅]₂ ( 3 ) by replacing 1 from a neighbouring molecule by the stronger donor 2 . In a closed system 3 obviously exists in an equilibrium with 1 and 2 . Both complexes are related to the previously studied derivatives of the 2‐dimethylamino‐perfluoro‐1‐phosphapropene ligand. The products were identified by spectroscopic (IR, NMR) investigations and comparison with the related phosphaalkene complexes.     

Two atropisomers of tri­carbonyl­[η6‐7‐chloro‐3‐(3‐chloro‐2‐methyl­phenyl)‐2,4,8‐tri­methyl‐1,2,3,4‐tetra­hydro‐2,4‐dibora‐1,3‐di­aza­naphthalene]­chromium(0)

The structures of two atropisomers of the title compound, [Cr(C₁₆H₁₈B₂Cl₂N₂)(CO)₃], are reported. For both compounds, the Cr(CO)₃ moiety is bound to the C₆ aromatic ring of the mol­ecule; the existence of atropisomers resulting from the non‐equivalence of both faces of the C₆ aromatic ring is a consequence of the 3‐chloro‐2‐methylphenyl ring being nearly perpendicular to the mean plane of the 2,4‐dibora‐1,3‐di­aza­naphthalene ring. The orientation of the Cr(CO)₃ tripod relative to the C₆ aromatic ring is such that it is nearly eclipsed in one isomer (2.4° rotation from being eclipsed with C—N, C—Cl and C—H) and slightly twisted (16.2°) from an eclipsed conformation in the other.     

Synthesis and structures of photoactive rhenium carbonyl complexes derived from 2‐(pyridin‐2‐yl)‐1,3‐benzothiazole, 2‐(quinolin‐2‐yl)‐1,3‐benzothiazole and 1,10‐phenanthroline

Carbon monoxide (CO) has recently been identified as a gaseous signaling molecule that exerts various salutary effects in mammalian pathophysiology. Photoactive metal carbonyl complexes (photoCORMs) are ideal exogenous candidates for more controllable and site‐specific CO delivery compared to gaseous CO. Along this line, our group has been engaged for the past few years in developing group‐7‐based photoCORMs towards the efficient eradication of various malignant cells. Moreover, several such complexes can be tracked within cancerous cells by virtue of their luminescence. The inherent luminecscent nature of some photoCORMs and the change in emission wavelength upon CO release also provide a covenient means to track the entry of the prodrug and, in some cases, both the entry and CO release from the prodrug. In continuation of the research circumscribing the development of trackable photoCORMs and also to graft such molecules covalently to conventional delivery vehicles, we report herein the synthesis and structures of three rhenium carbonyl complexes, namely, fac‐tricarbonyl[2‐(pyridin‐2‐yl)‐1,3‐benzothiazole‐κ²N ,N ′](4‐vinylpyridine‐κN )rhenium(I) trifluoromethanesulfonate, [Re(C₇H₇N)(C₁₂H₈N₂S)(CO)₃](CF₃SO₃), ( 1 ), fac‐tricarbonyl[2‐(quinolin‐2‐yl)‐1,3‐benzothiazole‐κ²N ,N ′](4‐vinylpyridine‐κN )rhenium(I) trifluoromethanesulfonate, [Re(C₇H₇N)(C₁₆H₁₀N₂S)(CO)₃](CF₃SO₃), ( 2 ), and fac‐tricarbonyl[1,10‐phenanthroline‐κ²N ,N ′](4‐vinylpyridine‐κN )rhenium(I) trifluoromethanesulfonate, [Re(C₇H₇N)(C₁₂H₈N₂)(CO)₃](CF₃SO₃), ( 3 ). In all three complexes, the Re^I center resides in a distorted octahedral coordination environment. These complexes exhibit CO release upon exposure to low‐power UV light. The apparent CO release rates of the complexes have been measured to assess their comparative CO‐donating capacity. The three complexes are highly luminescent and this in turn provides a convenient way to track the entry of the prodrug molecules within biological targets.     

Some Reactions of gem‐Dibromocyclopropanes and Metal Carbonyls

A series of gem‐dibromocyclopropanes were treated with various metal complexes. Among the metal complexes, Ru(CO)₂(PPh₃)₃, Ru(CO)₃(PPh₃)₂, and Mo(CO)₆ were able to remove a bromine atom from 1,1‐dibromo‐2‐phenylcyclopropanes ( 1 ) to yield a series of corresponding of 1‐bromo‐2‐phenylcyclopropanes ( 2 ). Upon the treatment of 1 with Cr(CO)₆ in DMSO, a series of allenes were obtained in good yields. The correlation between the rate of formation of allenes and the substituents on the benzene gives a negative coefficient which suggests the dibromocyclopropanes possesses as an electrophile toward to Cr(CO)₆. In the presence of Cr(CO)₆, gem‐dibromobicyclo[n,1,0]alkanes ( 4 ) in DMF or DMSO solution underwent the cleavage of carbon‐bromine bond followed by ring‐expansion and coupling reaction to form bicycloalkenes 7 .     

Metalated 1, 3‐Azaphospholes: η1‐(1H‐1, 3‐Benzazaphosphole‐P)M(CO)5 and μ2‐[(1, 3‐Benzazaphospholide‐P)(cyclopentadienide)nickel] Complexes

1H‐1, 3‐Benzazaphospholes react with M(CO)₅(THF) (M = Cr, Mo, W) to give thermally and relatively air stable η¹‐(1H‐1, 3‐Benzazaphosphole‐P)M(CO)₅ complexes. The ¹H‐ and ¹³C‐NMR‐data are in accordance with the preservation of the phosphaaromatic π‐system of the ligand. The strong upfield ³¹P coordination shift, particularly of the Mo and W complexes, forms a contrast to the downfield‐shifts of phosphine‐M(CO)₅ complexes and classifies benzazaphospholes as weak donor but efficient acceptor ligands. Nickelocene reacts as organometallic species with metalation of the NH‐function. The resulting ambident 1, 3‐benzazaphospholide anions prefer a μ₂‐coordination of the η⁵‐CpNi‐fragment at phosphorus to coordination at nitrogen or a η³‐heteroallyl‐η⁵‐CpNi‐semisandwich structure. This is shown by characteristic NMR data and the crystal structure analysis of a η⁵‐CpNi‐benzazaphospholide. The latter is a P‐bridging dimer with a planar Ni₂P₂ ring and trans‐configuration of the two planar heterocyclic phosphido ligands arranged perpendicular to the four‐membered ring.     

Synthesis and structures of photoactive manganese–carbonyl complexes derived from 2‐(pyridin‐2‐yl)‐1,3‐benzothiazole and 2‐(quinolin‐2‐yl)‐1,3‐benzothiazole

PhotoCORMs (photo‐active CO‐releasing molecules) have emerged as a class of CO donors where the CO release process can be triggered upon illumination with light of appropriate wavelength. We have recently reported an Mn‐based photoCORM, namely [MnBr(pbt)(CO)₃] [pbt is 2‐(pyridin‐2‐yl)‐1,3‐benzothiazole], where the CO release event can be tracked within cellular milieu by virtue of the emergence of strong blue fluorescence. In pursuit of developing more such trackable photoCORMs, we report herein the syntheses and structural characterization of two Mn^I–carbonyl complexes, namely fac‐tricarbonylchlorido[2‐(pyridin‐2‐yl)‐1,3‐benzothiazole‐κ²N ,N ′]manganese(I), [MnCl(C₁₂H₈N₂S)(CO)₃], (1), and fac‐tricarbonylchlorido[2‐(quinolin‐2‐yl)‐1,3‐benzothiazole‐κ²N ,N ′]manganese(I), [MnCl(C₁₆H₁₀N₂S)(CO)₃], (2). In both complexes, the Mn^I center resides in a distorted octahedral coordination environment. Weak intermolecular C—H…Cl contacts in complex (1) and Cl…S contacts in complex (2) consolidate their extended structures. These complexes also exhibit CO release upon exposure to low‐power broadband visible light. The apparent CO release rates for the two complexes have been measured to compare their CO donating capacity. The fluorogenic 2‐(pyridin‐2‐yl)‐1,3‐benzothiazole and 2‐(quinolin‐2‐yl)‐1,3‐benzothiazole ligands provide a convenient way to track the CO release event through the `turn‐ON' fluorescence which results upon de‐ligation of the ligands from their respective metal centers following CO photorelease.     

Metal Complexes with Biologically Important Ligands. CLXVI Tetracarbonyl Complexes of Chromium(0) and Molybdenum(0) with Schiff Bases from Pyridine‐2‐carboxaldehyde and α‐Amino Acid Esters as N,N‐Chelate Ligands

The complexes [M(CO)₄(pyridyl‐CH=N‐CHRCO₂R′)] (M = Cr, Mo; R = H, CH₃, CH(CH₃)₂, CH₂CH(CH₃)₂) were obtained by reaction of the Schiff bases from pyridine‐2‐carboxaldehyde and glycine, L‐alanine, L‐valine or L‐leucine esters with the norbornadiene complexes [M(CO)₄(nbd)] and were characterized by IR, ¹H and ¹³C NMR and UV‐vis spectra. The deeply colored complexes exhibit solvatochromism.     

Trapping of Tricarbonyl(η1,η2‐homoallyl)iron and Tricarbonyl(η3‐allyl)iron Anion Intermediates with 2‐(Phenylsulfonyl)‐3‐phenyloxaziridine

The addition of reactive carbanions to (η⁴‐1,3‐diene)Fe(CO)₃ complexes at ?78 °C and 25 °C produced putative homoallyl and allyl anion complexes, respectively. Reaction of the reactive intermediates with 2‐(phenylsulfonyl)‐3‐phenyloxaziridine afforded nucleophilic substituted (η⁴‐1,3‐diene)Fe(CO)₃ complexes.     

(η6‐Bi­phenyl)­tri­carbonyl­chromium and μ‐(η6:η6)‐bi­phenyl‐bis­(tricarbonyl­chromium)

The title compounds, [Cr(C₁₂H₁₀)(CO)₃] and [Cr₂(C₁₂H₁₀)(CO)₆], serve as a fundamental standard of comparison for other mono‐ and polysubstituted (η⁶‐bi­phenyl)­tri­carbonyl­chromium compounds. (η⁶‐Bi­phenyl)­tri­carbonyl­chromium has a typical piano‐stool coordination about the Cr center, and the dihedral angle between the planes of the phenyl rings is 23.55 (5)°. The corresponding angle in μ‐(η⁶:η⁶)‐bi­phenyl‐bis­(tri­carbonyl­chromium) is 0° because the mol­ecule occupies a crystallographic inversion center; the Cr atoms reside on opposite sides of the bi­phenyl ligand. Density functional theory and natural bonding orbital theory analyses were used to scrutinize the geometry of these and closely related compounds to explain important structural features.     

Heterobimetallic Complexes: Substitution Effects in the [Tetracarbonylrhodiumbis{μ‐(diphenylphosphino)}{μ‐(η:η2‐(4‐diphenylphosphino‐κP)‐2‐methyl‐oxobutyl)}molybdenum](Mo‐Rh) System

Syntheses of the array of heterobimetallic complexes [(OC)₃M(μ‐PPh₂)₂(μ‐O‐C(CHMe(CH₂)₂PPh₂)RhL], M = Cr, Mo, W, L = ^tBuNC, are described, extending the previous study of the counterpart array for L = CO. A single crystal X‐ray structure determination is reported for the M = Mo adduct, enabling comparison with its previously reported L = CO counterpart, for which an improved redetermination is also reported. In the present complex the ^tBuNC ligand is found to be much more weakly bound (Rh‐C 2.026(5) Å) than the carbonyl group it displaces (Rh‐C 1.945(2) Å) with concomitant minor impact on the remainder of the rhodium ambience.