Synthesis and reactivity of fluorinated ferracarborane anions

The ferracarborane [N(PPh3)2][6,6,6,10,10,10-(CO)6-closo-6,10,1-Fe2CB7H8] reacts in CH2Cl2 with 3 molar equivalents of Ag[PF6] to yield the trifluoro-substituted species [N(PPh3)2][7,8,9-F3-6,6,6,10,10,10-(CO)6-closo-6,10,1-Fe2CB7H5]. Compound undergoes structural rearrangement in toluene at reflux temperatures, forming [N(PPh3)2][8,9,10-F3-6,6,6,7,7,7-(CO)6-closo-6,7,1-Fe2CB7H5]. Alternatively, reaction of either or with a 10-fold excess of Ag[PF6] in CH2Cl2 forms two species: namely, [N(PPh3)2][2,7,9,10-F4-6,6,6,8,8,8-(CO)6-closo-6,8,1-Fe2CB7H4], in which one further B-F substitution has occurred and the {Fe2CB7} cluster core has rearranged, plus a mono-iron co-product, [N(PPh3)2][3,8,9-F3-7,7,7-(CO)3-closo-7,1-FeCB7H5] that is formed by polyhedral contraction. Treatment of with [NO][BF4] in CH2Cl2 results in CO substitution at the 4-connected iron vertex [Fe10], producing the zwitterionic complex [7,8,9-F3-6,6,6,10,10-(CO)5-10-NO-closo-6,10,1-Fe2CB7H5]. Addition of Me3NO to a mixture of and PEt3 in CH2Cl2 also results in CO substitution, forming the isomeric species [N(PPh3)2][7,8,9-F3-6,6,m,10,10-(CO)5-n-PEt3-closo-6,10,1-Fe2CB7H5] [m=6, n=10; m=10, n=6] in a 5:1 ratio. Treatment of with [NO][BF4] and then CNBut in CH2Cl2 allows further, successive CO substitution at Fe10 to yield first a neutral, zwitterionic complex [7,8,9-F3-6,6,6,10-(CO)4-10-NO-10-PEt3-closo-6,10,1-Fe2CB7H5] and then [7,8,9-F3-6,6,6-(CO)3-10-CNBut-10-NO-10-PEt3-closo-6,10,1-Fe2CB7H5]. The molecular structures of compounds and have been established by X-ray diffraction.     

Cucurbit[n]uril analogues

[structure: see text] Cucurbits come in a variety of sizes, shapes, and colors. We present a building block approach that allows the tailor-made synthesis of CB[5], CB[6], and CB[7] analogues whose sizes, shapes, and colors differ from those of the known CB[n].     

Acyclic congener of cucurbituril: synthesis and recognition properties

The cucurbit[n]uril (CB[n]) family of macrocycles occupies a prominent role in molecular recognition and self-assembly studies despite the current inability to access specific cucurbit[n]uril homologues, derivatives, and analogues by straightforward tailor-made synthetic procedures. In this paper, we explore an approach that circumvents the challenges posed by the tailor-made synthesis of macrocyclic CB[n] by preparing 1, which functions as an acyclic CB[6] congener. The o-xylylene connections to the glycoluril rings preorganize 1 into the (a,a,a,a)-1 conformation required for binding and reduce its tendency to undergo self-association. We surveyed the binding properties of 1 toward 16 amines (K(a) 相似文献   

Penta- and hexaruthenium carbonyl 'raft' complexes supported by monocarborane cage ligands

Reaction between [PPh4][closo-4-CB8H9] and [Ru3(CO)12] in refluxing toluene affords the unprecedented hexaruthenium metallacarborane salt [PPh4][2,3,7-{Ru(CO)3}-2,6,11-{Ru(CO)3}-7,11,12-{Ru(CO)3}-3,6,12-(micro-H)3-2,2,7,7,11,11-(CO)6-closo-2,7,11,1-Ru3CB8H6] (1a), which contains a planar Ru6 'raft' supported by a {CB8} monocarborane cluster. Addition of [CuCl(PPh3)]4 and Tl[PF6] to a CH2Cl2 solution of 1a results in simple cation replacement, forming the analogous [Cu(PPh3)3]+ salt (1b). The phenyl-substituted monocarborane [NEt4][6-Ph-nido-6-CB9H11] reacts with [Ru3(CO)12] in refluxing 1,2-dimethoxyethane to afford the pentaruthenium cluster species [N(PPh3)2][2,3,7-{Ru(CO)3}-3,4,8-{Ru(CO)3}-7,8-(micro-H)2-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru3CB8H6] (2), after addition of [N(PPh3)2]Cl. Treatment of 2 with [CuCl(PPh3)]4 and Tl[PF6] in CH2Cl2 forms the zwitterionic complex [10,12-{exo-Cu(PPh3)2}-2,3,7-{Ru(CO)3}-3,4,8-{Ru(CO)3}-7,8,10,12-(micro-H)4-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru3CB8H4] (3). Substitution of CO by PPh3 with concomitant cation replacement occurs on introduction of [AuCl(PPh3)], Tl[PF6], and PPh3 to a CH2Cl2 solution of 2, forming [Au(PPh3)2][2,3,7-{Ru(CO)2PPh3}-3,4,8-{Ru(CO)2PPh3}-7,8-(micro-H)2-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru3CB8H6] (4). Crystallographic studies confirmed the cluster architectures in 1b, 2, and 3.     

Binding modes of cucurbit[6]uril and cucurbit[7]uril with a tetracationic bis(viologen) guest

Binding behaviors of two cucurbit[n]urils (CB[n]) hosts with the [CH3bpy(CH2)6bpyCH3]4+ (bpy = 4,4'-bipyridinium) guest were investigated by 1H NMR and MALDI-TOF-MS experiments. While the CB[6] and CB[7] form [2]pseudorotaxanes with the host located over the hexamethylene chain of the guest, only the CB[7] forms a [3]pseudorotaxane with both host molecules residing over the bipyridinium groups. The initial CB[7] host vacates the inclusion of the hexamethylene chain as a result of the electrostatic and steric repulsions that would arise in simultaneous binding of adjacent aliphatic and aromatic portions of the guest.     

Cucurbit[7]uril: an amorphous molecular material for highly selective carbon dioxide uptake

Cucurbit[7]uril (CB[7]), in its amorphous solid state, shows one of the highest CO(2) sorption capacities among known organic porous materials at 298 K and 0.1 and 1 bar. In addition to the highest CO(2) capacity, CB[7] also shows remarkable selectivity of CO(2) over N(2) and CH(4). These properties, along with the existence of readily available precursors, indicate amorphous CB[7] might find applications in recycling CO(2) particularly considering the easy synthesis and potentially low manufacturing costs.     

Formation of intramolecular rings in ferramonocarbollide complexes

Addition of PPh 2Cl and Tl[PF 6] to CH 2Cl 2 solutions of [N(PPh 3) 2][6,6,6-(CO) 3- closo-6,1-FeCB 8H 9] ( 1) affords the isomeric B-substituted species [6,6,6-(CO) 3- n-(PHPh 2)- closo-6,1-FeCB 8H 8] [ n = 7 ( 2a) or 10 ( 2b)]. Deprotonation (NaH) of the phosphine ligand in 2a, with subsequent addition of [IrCl(CO)(PPh 3) 2] and Tl[PF 6], yields the neutral, zwitterionic complex [6,6,6-(CO) 3-4,7-mu-{Ir(H)(CO)(PPh 3) 2PPh 2}- closo-6,1-FeCB 8H 7] ( 3), which contains a B-P-Ir- B ring. Alternatively, deprotonation using NEt 3, followed by addition of HC[triple bond]CCH 2Br, affords [6,6,6-(CO) 3-7-(PPh 2CCMe)- closo-6,1-FeCB 8H 8] ( 4). Addition of [Co 2(CO) 8] to CH 2Cl 2 solutions of the latter gives [6,6,6-(CO) 3-7-(PPh 2-{(mu-eta (2):eta (2)-CCMe)Co 2(CO) 6})- closo-6,1-FeCB 8H 8] ( 5), which contains a {C 2Co 2} tetrahedron. In the absence of added substrates, deprotonation of the PHPh 2 group in compounds 2, followed by reaction of the resulting anions with CH 2Cl 2 solvent, affords [6,6,6-(CO) 3- n-(PPh 2CH 2Cl)- closo-6,1-FeCB 8H 8] [ n = 7 ( 6a) or 10 ( 6b)] plus [6,6-(CO) 2-6,7-mu-{PPh 2CH 2PPh 2}- closo-6,1-FeCB 8H 8] ( 7, formed from 2a), of which the latter species possesses an intramolecular B-P-C-P- Fe ring. Addition of Me 3NO to CH 2Cl 2 solutions of 2a causes loss of an Fe-bound CO ligand and formation of [6,6-(CO) 2-6,7-mu-{NMe 2CH 2PPh 2}- closo-6,1-FeCB 8H 8] ( 8), which incorporates a B-P-C-N- Fe ring. A similar reaction in the presence of ligands L yields [6,6-(CO) 2-6-L-7-(PPh 2CH 2Cl)- closo-6,1-FeCB 8H 8] [L = PEt 3 ( 9) or CNBu (t) ( 10)], in addition to 8.     

三(三甲硅基)环戊二烯基三羰基钼负离子的反应性

三(三甲硅基)环戊二烯基三羰基钼负离子锂盐[{η^5-(Me~3Si)~3C~5H~2}Mo(CO)~3]^-Li^+(1), 分别与MeI、phCH~2Cl及ClCH~2COOC~2H~5反应生成相应的烃基化钼衍生物[{η^5-(Me~3Si)~3C~5H~2}Mo(CO)~3R,] (R=-CH~3, 2; -CH~2ph, 3;-CH~2COOC~2H~5, 4)。1与PCl~3反应除得到预期的钼氯化物[{η^5-(Me~3Si)~3C~5H~2}Mo(CO)~3Cl](5)外, 主要得到钼磷氯化物[{η^5-(Me~3Si)~3C~5H~2}Mo(CO)~3PCl~2] 6; 1与碘反应得到钼碘化物[{η^5-(Me~3Si)~3C~5H~2}Mo(CO)~3I] 7; 1与HOAc作用后分别和CCl~4、NBS室温反应, 仅分离到脱去一个Me~3Si的钼卤化物[{η^5-(Me~3Si)~2C~5H~2}Mo(CO)~3X], (X:Cl, 8; Br, 9)。     

Guest Inclusion in Cucurbiturils Studied by ESR and DFT: The Case of Nitroxide Radicals and Spin Adducts of DMPO and MNP

We present an ESR and DFT study of the interaction of cucurbiturils CB[6], CB[7], and CB[8] with di-tert-butyl nitroxide ((CH(3))(3)C)(2)NO (DTBN) and with spin adducts of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and 2-methyl-2-nitrosopropane (MNP). The primary goal was to understand the structural parameters that determine the inclusion mechanism in the CBs using DTBN, a nitroxide with great sensitivity to the local environment. In addition, we focused on the interactions with CBs of the spin adducts DMPO/OH and MNP/CH(2)COOH generated in aqueous CH(3)COOH. A range of interactions between DTBN and CBs was identified for pH 3.2, 7, and 10. No complexation of DTBN with CB[6] was deduced in this pH range. The interaction between DTBN and CB[7] is evident at all pH values: "in" and "out" nitroxides, with (14)N hyperfine splitting, a(N), values of 15.5 and 17.1 G, respectively, were detected by ESR. Interaction of DTBN with CB[8] was also detected for all pH values, and the only species had a(N) = 16.4 G, a result that can be rationalized by an "in" nitroxide in a less hydrophobic environment compared to CB[7]. Computational studies indicated that the DTBN complex with CB[7] is thermodynamically favored compared to that in CB[8]; the orientations of the NO group are parallel to the CB[7] plane and perpendicular to the CB[8] plane (pointing toward the annulus). Addition of sodium ions led to the ESR detection of a three-component complex between CB[7], DTBN, and the cations; the ternary complex was not detected for CB[8]. The DMPO/OH spin adduct was stabilized in the presence of CB[7], but the effect on a(N) was negligible, indicating that the N-O group is located outside the CB cavity. Computational studies indicated more favorable energetics of complexation for DMPO/OH in CB[7] compared to DTBN. An increase of a(N) was detected in the presence of CB[7] for the MNP/CH(2)COOH adduct generated in CH(3)COOH, a result that was assigned to the generation of the three-component radical between the spin adduct, sodium cations, and CB[7].     

The cucurbit[n]uril family: prime components for self-sorting systems

We determined the values of Ka for a wide range of host-guest complexes of cucurbit[n]uril (CB[n]), where n = 6-8, using 1H NMR competition experiments referenced to absolute binding constants measured by UV/vis titration. We find that the larger homologues--CB[7] and CB[8]--individually maintain the size, shape, and functional group selectivity that typifies the recognition behavior of CB[6]. The cavity of CB[7] is found to effectively host trimethylsilyl groups. Remarkably, the values of Ka for the interaction of CB[7] with adamantane derivatives 22-24 exceeds 10(12) M(-1)! The high levels of selectivity observed for each CB[n] individually is also observed for the CB[n] family collectively. That is, the selectivities of CB[6], CB[7], and CB[8] toward a common guest can be remarkably large. For example, guests 1, 3, and 11 prefer CB[8] relative to CB[7] by factors greater than 10(7), 10(6), and 3000, respectively. Conversely, guests 23 and 24 prefer CB[7] relative to CB[8] by factors greater than 5100 and 990, respectively. The high levels of selectivity observed individually and collectively for the CB[n] family renders them prime components for the preparation of functional biomimetic self-sorting systems.     

Thermodynamic modeling of the phase behavior of binary systems of ionic liquids and carbon dioxide with the group contribution equation of state

The group contribution equation of state (GC-EOS) was applied to predict the phase behavior of binary systems of ionic liquids of the homologous families 1-alkyl-3-methylimidazolium hexafluorophosphate and tetrafluoroborate with CO2. Pure group parameters for the new ionic liquid functional groups [-mim][PF6] and [-mim][BF4] and interaction parameters between these groups and the paraffin (CH3, CH2) and CO2 groups were estimated. The GC-EOS extended with the new parameters was applied to predict high-pressure phase equilibria in binary mixtures of the ionic liquids [emim][PF6], [bmim][PF6], [hmim][PF6], [bmim][BF4], [hmim][BF4], and [omim][BF4] with CO2. The agreement between experimental and predicted bubble point data for the ionic liquids was excellent for pressures up to 20 MPa, and even for pressures up to about 100 MPa, the agreement was good. The results show the capability of the GC-EOS to describe phase equilibria of systems consisting of ionic liquids.     

Synthesis of disubstituted cucurbit[6]uril and its rotaxane derivative

Synthesis of diphenyl cucurbit[6]uril (CB[6]) has been achieved via co-oligomerization of diphenyl glycoluril and unsubstituted glycoluril. The unsymmetrically substituted CB[6], Ph(2)CB[6], was further converted to a rotaxane incorporating bis(dinitrophenyl)spermine. [reaction: see text]     

Mechanism of the conversion of inverted CB[6] to CB[6

Inverted cucurbit[n]urils (iCB[n]) form as intermediates during the synthesis of cucurbit[n]urils from glycoluril and formaldehyde in HCl (85 degrees C). Product resubmission experiments establish that the diastereomeric iCB[6] and iCB[7] are kinetic products that are less stable thermodynamically than CB[6] or CB[7] (>2.8 kcal mol(-1)). When iCB[6] or iCB[7] is heated under aqueous acidic conditions, a preference for ring contraction is noted in the formation of CB[5] and CB[6], respectively. Interestingly, under anhydrous acidic conditions ring size is preserved with iCB[6] delivering CB[6] cleanly. To establish the intramolecular nature of the iCB[6] to CB[6] conversion under anhydrous, but not aqueous, acidic conditions we performed crossover experiments involving mixtures of iCB[6] and its (13)C=O labeled isotopomer (13)C(12)-iCB[6]. An unusual diastereomeric CB[6] with a M?bius geometry (13) is proposed as a mechanistic intermediate in the conversion of iCB[6] to CB[6] under anhydrous acidic conditions. The improved mechanistic understanding provided by this study suggests improved routes to CB[n]-type compounds.     

Water structuring inside the cavities of cucurbit[n]urils (n = 5–8): a quantum-chemical forecast

In this work we report findings of the quantum-chemical examination of water structuring in the cavities of cucurbit[n]urils (CB[n]), n?=?5–8 obtained within the density functional theory. The thermodynamically most stable structures of inclusion compounds (H₂O)_m@CB[n] were determined for different numbers m of H₂O molecules inside the cavities. From the viewpoint of thermodynamics, the most probable numbers m of water molecules in the CB[n] homologues are the following: m?=?2 for CB[5], m?=?4 for CB[6], m?=?8 for CB[7] and m?=?10 for CB[8]. For the case of CB[6] synthesized in aqueous solution, we compared its experimental IR spectrum with that calculated quantum-chemically for the model inclusion systems (H₂O)_m@CB[6] where m ranges from 1 to 6. The best agreement between the experimental and theoretical spectra was observed for (H₂O)₄@CB[6], in complete agreement with the conclusion made based on the thermodynamic estimations. Our results are also in good agreement with other available estimates of the most probable number of water molecules in CB[n].     

Sigma-organyl complexes of ruthenium and osmium supported by a mixed-donor ligand

A series of vinyl, aryl, acetylide and silyl complexes [Ru(R)(kappa2-MI)(CO)(PPh3)2] (R = CH=CH2, CH=CHPh, CH=CHC6H4CH3-4, CH=CH(t)Bu, CH=2OH, C(C triple bond CPh)=CHPh, C6H5, C triple bond CPh, SiMe2OEt; MI = 1-methylimidazole-2-thiolate) were prepared from either [Ru(R)Cl(CO)(PPh3)2] or [Ru(R)Cl(CO)(BTD)(PPh3)2](BTD = 2,1,3-benzothiadiazole) by reaction with the nitrogen-sulfur mixed-donor ligand, 1-methyl-2-mercaptoimidazole (HMI), in the presence of base. In the same manner, [Os(CH=CHPh)(kappa2-MI)(CO)(PPh3)2] was prepared from [Os(CH=CHPh)(CO)Cl(BTD)(PPh3)2]. The in situ hydroruthenation of 1-ethynylcyclohexan-1-ol by [RuH(CO)Cl(BTD)(PPh3)2] and subsequent addition of the HMI ligand and excess sodium methoxide yielded the dehydrated 1,3-dienyl complex [Ru(CH=CHC6H9)(kappa2-MI)(CO)(PPh3)2]. Dehydration of the complex [Ru(CH=CHCPh2OH)(kappa2-MI)(CO)(PPh3)2] with HBF4 yielded the vinyl carbene [Ru(=CHCH=CPh2)(kappa2-MI)(CO)(PPh3)2]BF4. The hydride complexes [MH(kappa2-MI)(CO)(PPh3)2](M = Ru, Os) were obtained from the reaction of HMI and KOH with [RuHCl(CO)(PPh3)3] and [OsHCl(CO)(BTD)(PPh3)2], respectively. Reaction of [Ru(CH=CHC6H4CH3-4)(kappa2-MI)(CO)(PPh3)2] with excess HC triple bond CPh leads to isolation of the acetylide complex [Ru(C triple bond CPh)(kappa2-MI)(CO)(PPh3)2], which is also accessible by direct reaction of [Ru(C triple bond CPh)Cl(CO)(BTD)(PPh3)2] with 1-methyl-2-mercaptoimidazole and NaOMe. The thiocarbonyl complex [Ru(CPh = CHPh)Cl(CS)(PPh3)2] reacted with HMI and NaOMe without migration to yield [Ru(CPh= CHPh)(kappa2-MI)(CS)(PPh3)2], while treatment of [Ru(CH=CHPh)Cl(CO)2(PPh3)2] with HMI yielded the monodentate acyl product [Ru{eta(1)-C(=O)CH=CHPh}(kappa2-MI)(CO)(PPh3)2]. The single-crystal X-ray structures of five complexes bearing vinyl, aryl, acetylide and dienyl functionality are reported.     

C-F or C-H bond activation and C-C coupling reactions of fluorinated pyridines at rhodium: synthesis, structure and reactivity of a variety of tetrafluoropyridyl complexes

Reactions of [RhH(PEt3)3] (1) or [RhH(PEt3)4] (2) with pentafluoropyridine or 2,3,5,6-tetrafluoropyridine afford the activation product [Rh(4-C5NF4)(PEt3)3] (3). Treatment of 3 with CO, 13CO or CNtBu effects the formation of trans-[Rh(4-C5NF4)(CO)(PEt3)2] (4a), trans-[Rh(4-C5NF4)(13CO)(PEt3)2] (4b) and trans-[Rh(4-C5NF4)(CNtBu)(PEt3)2] (5). The rhodium(III) compounds trans-[RhI(CH3)(4-C5NF4)(PEt3)2] (6a) and trans-[RhI(13CH3)(4-C5NF4)(PEt3)2] (6b) are accessible on reaction of 3 with CH3I or 13CH3I. In the presence of CO or 13CO these complexes convert into trans-[RhI(CH3)(4-C5NF4)(CO)(PEt3)2] (7a), trans-[RhI(13CH3)(4-C5NF4)(CO)(PEt3)2] (7b) and trans-[RhI(13CH3)(4-C5NF4)(13CO)(PEt3)2] (7c). The trans arrangement of the carbonyl and methyl ligand in 7a-7c has been confirmed by the 13C-13C coupling constant in the 13C NMR spectrum of 7c. A reaction of 4a or 4b with CH3I or 13CH3I yields the acyl compounds trans-[RhI(COCH3)(4-C5NF4)(PEt3)2] (8a) and trans-[RhI(13CO13CH3)(4-C5NF4)(PEt3)2] (8b), respectively. Complex 8a slowly reacts with more CH3I to give [PEt3Me][Rh(I)2(COCH3)(4-C5NF4)(PEt3)](9). On heating a solution of 7a, the complex trans-[RhI(CO)(PEt3)2] (10) and the C-C coupled product 4-methyltetrafluoropyridine (11) have been obtained. Complex 8a also forms 10 at elevated temperatures in the presence of CO together with the new ketone 4-acetyltetrafluoropyridine (12). The structures of the complexes 3, 4a, 5, 6a, 8a and 9 have been determined by X-ray crystallography. 19F-1H HMQC NMR solution spectra of 6a and 8a reveal a close contact of the methyl groups in the phosphine to the methyl or acyl ligand bound at rhodium.     

Gold(I) macrocycles and topologically chiral [2]catenanes

The design and synthesis of a new type of topologically chiral [2]catenane is reported. The compounds are formed easily by self-assembly on reaction of the oligomeric digold(I) diacetylide precursor complex [[4-BrC(6)H(4)CH(4-C(6)H(4)OCH(2)CCAu)(2)](n)] with diphosphine ligands. Reactions with the diphosphines PP = bis(diphenylphosphinophoshino)acetylene, trans-1,2-bis(diphenylphosphino)ethylene, bis(diphenylphosphino)ethane, and 1,1'-bis(diphenylphosphino)ferrocene yield simple ring complexes [4-BrC(6)H(4)CH(4-C(6)H(4)OCH(2)CCAu)(2)(mu-PP)] as the only products, since the spacer groups in the diphosphines are not long enough or are too bulky to allow catenane formation. Reaction with PP = bis(diphenylphosphino)propane or bis(diphenylphosphino)butane gave [2]catenane complexes [[4-BrC(6)H(4)CH(4-C(6)H(4)OCH(2)CCAu)(2)(mu-PP)](2)], whose structures are confirmed crystallographically. The macrocyclic ring compounds have C(s) symmetry but, as a result of the presence of the unsymmetrical "hinge group" 4-BrC(6)H(4)CH, the [2]catenanes have C(2) symmetry and so are topologically chiral. In favorable cases, the formation of the [2]catenane can be proved by NMR spectroscopy since catenane formation leads to nonequivalence of most ring atoms. The formation of the [2]catenanes was successfully predicted based on the conformation of the precursor bis(phenol), and it is argued that the methods used should be more generally applicable to the synthesis of functionally substituted supermolecules of interest for application in molecular devices.     

Synthesis and some properties of binuclear ruthenocenes bridged by oligoynes: formation of bis(cyclopentadienylidene)cumulene diruthenium complexes in the two-electron oxidation

The monoynes [Rc*C[triple bond]CRc*] and [Rc'C[triple bond]CRc'] were obtained in improved yields using [Mo(CO)6]/2-FC6H5OH as a catalyst in the alkyne metathesis of [Rc*C[triple bond]CMe] and [Rc'C[triple bond]CMe], respectively (Rc = ruthenocenyl, Rc* = 1',2',3',4',5'-pentamethylruthenocenyl, and Rc' = 2',3',4',5'-tetramethylruthenocenyl groups). The diynes [Rc*(C[triple bond]C)2Rc*] and [Rc'(C[triple bond]C)2Rc'] were synthesized by the oxidative coupling of the corresponding terminal ethynes in good yields. The triyne [Rc*(C[triple bond]C)3Rc*] and the tetrayne [Rc*(C[triple bond]C)4Rc*] were prepared by the hetero- and homocoupling of [Rc*C[triple bond]CC[triple bond]CH], which was obtained from the reaction of [Rc*C[triple bond]CCHO] with Li[N2CSiMe3], respectively. Although the oxidation waves did not always exhibit a clear two-electron oxidation process, the oxidation potentials shifted to a lower potential with an increase in the number of methyl substituents on the ruthenocenyl ring, and shifted to a higher potential with the increase in the number of C[triple bond]C units; this result is in contrast to that found in the [Rc(CH=CH)(n)Rc] series. The chemical oxidation of [Rc'C[triple bond]CRc'] yielded a stable two-electron-oxidized species, the structure of which was confirmed by X-ray crystallography to be [Ru2(mu2-eta(6):eta(6)-C5Me4C=CC5Me4)(eta-C5H5)2](BF4)2. Changing the substituents (Rc, Rc*, and Rc') had no effect on the chemical oxidation, but in the case of the Rc' series the Me substituent increased the stability of the two-electron-oxidized species in solution. The diyne [Rc*(C[triple bond]C)2Rc*] and the triyne [Rc*(C[triple bond]C)3Rc*] also gave a similar but unstable two-electron-oxidized species. In acetone or acetonitrile, the two-electron-oxidized species of [Rc*C[triple bond]CRc*] and [Rc*(C[triple bond]C)2Rc*] gradually formed the corresponding bis(fulvene)-type complexes. This implies that the two-electron-oxidized species of [Rc*(C[triple bond]C)(n)Rc*] are destabilized with the increasing n.     

Synthesis, spectroscopic, and structural studies on transition metal complexes involving homoleptic tripodal selenoether and telluroether coordination

The reaction of [MCl2(NCMe)2] (M = Pd or Pt) with 2 molar equiv of MeC(CH2ER)3 (E = Se, R = Me; E = Te, R = Me or Ph) and 2 molar equiv of TlPF6 affords the bis ligand complexes [M(MeC(CH2ER)3)2][PF6]2. The crystal structure of [Pt(MeC(CH2SeMe)3)2][PF6]2 (C16H36F12P2PtSe6, a = 12.272(10) A, b = 18.563(9) A, c = 15.285(7) A, beta = 113.18(3) degrees, monoclinic, P2(1)/n, Z = 4) confirms distorted square planar Se4 coordination at Pt(II), derived from two bidentate tripod selenoethers with the remaining arm not coordinated and directed away from the metal center. Solution NMR studies indicate that these species are fluxional and that the telluroether complexes are rather unstable in solution. The octahedral bis tripod complexes [Ru(MeC(CH2SMe)3)2][CF3-SO3]2 and [Ru(MeC(CH2TePh)3)2][CF3SO3]2 are obtained from [Ru(dmf)6][CF3SO3]3 and tripod ligand in EtOH solution. The thioether complex (C18H36F6O6RuS8, a = 8.658(3) A, b = 11.533(3) A, c = 8.659(2) A, alpha = 108.33(2) degrees, beta = 91.53(3) degrees, gamma = 106.01(2) degrees, triclinic, P1, Z = 1) is isostructural with its selenoether analogue, involving two facially coordinated trithioether ligands in the syn configuration. NMR spectroscopy confirms that this configuration is retained in solution for all of the bis tripod Ru(II) complexes. These low-spin d6 complexes show unusually high ligand field splittings. The hexaselenoether Rh(III) complex [Rh(MeC(CH2SeMe)3)2][PF6]3 was obtained by treatment of [Rh(H2O)6]3+ with 2 molar equiv of MeC(CH2SeMe)3 in aqueous MeOH in the presence of excess PF6- anion, while the iridium(III) analogue [Ir(MeC(CH2SeMe)3)2][PF6]3 was obtained via the reaction of the Ir(I) precursor [IrCl(C8H14)2]2 with the selenoether tripod in MeOH/aqueous HBF4. NMR studies reveal different invertomers in solution for both the Rh and Ir species. The Cu(I) complexes [Cu(MeC(CH2ER)3)2]PF6 were obtained from [Cu(NCMe)4]PF6 and tripod ligand in CH2Cl2 solution. The corresponding Ag(I) species [Ag(MeC(CH2TeR)3)2]CF3SO3 (R = Me or Ph) were obtained from Ag[CF3SO3] and tripod telluroether. In contrast, a similar reaction with 2 molar equiv of MeC(CH2SeMe)3 afforded only the 1:1 complex [Ag(MeC(CH2SeMe)3)]CF3SO3. The structure of this species (C9H18AgF3O3SSe3, a = 8.120(3) A, b = 15.374(3) A, c = 14.071(2) A, beta = 93.86(2) degrees, monoclinic, P2(1)/n, Z = 4) reveals a distorted trigonal planar geometry at Ag(I) derived from one bidentate selenoether and one monodentate selenoether. These units are then linked to adjacent Ag(I) ions to give a one-dimensional linear chain cation.     

Synthesis, structural characterization, gas sorption and guest-exchange studies of the lightweight, porous metal-organic framework alpha-[Mg3(O2CH)6

Unsolvated magnesium formate crystallizes upon reaction of the metal nitrate with formic acid in DMF at elevated temperatures. Single-crystal XRD studies reveal the formation of [Mg3(O2CH)6 [symbol: see text] DMF], 1, a metal-organic framework with DMF molecules filling the channels of an extended diamondoid lattice. The DMF molecules in 1 can be entirely removed without disruption to the framework, giving the guest-free material alpha-[Mg3(O2CH)6], 2. Compound 2 has been characterized by both powder and single-crystal XRD studies. Thermogravimetric analyses of 1 show guest loss from 120 to 190 degrees C, with decomposition of the sample at approximately 417 degrees C. Gas sorption studies using both N2 and H2 indicate that the framework displays permanent porosity. The porosity of the framework is further demonstrated by the ability of 2 to uptake a variety of small molecules upon soaking. Single-crystal XRD studies have been completed on the six inclusion compounds [Mg3(O2CH)6 [symbol: see text] THF], 3; [Mg3(O2CH)6 [symbol: see text] Et2O], 4; [Mg3(O2CH)6 [symbol: see text] Me2CO], 5; [Mg3(O2CH)6 [symbol: see text] C6H6], 6; [Mg3(O2CH)6 [symbol: see text] EtOH], 7; and [Mg3(O2CH)(6) [symbol: see text] MeOH], 8. Analyses of the metrical parameters of 1-8 indicate that the framework has the ability to contract or expand depending on the nature of the guest present.