The electronic structures of diruthenium complexes containing an oligo(phenylene ethynylene) bridging ligand, and some related molecular structures

The complexes [{Cp'(L(2))Ru}C≡CC(6)H(4)C≡CC(6)H(2)(OMe)(2)C≡CC(6)H(4)C≡C{Ru(L(2))Cp'}](L(2) = (PPh(3))(2), Cp' = Cp; L(2) = dppe, Cp' = Cp*) in which the metal centres are bridged by an oligomeric phenylene ethynylene (OPE) ligand have been prepared and the electronic structure of these representative ruthenium-capped OPEs investigated using a combination of electrochemical, UV-vis-NIR and IR spectroelectrochemical methods, and DFT-based calculations. The diruthenium complexes are oxidised to the thermodynamically stable dications [Cp'Ru(L(2))C≡CC(6)H(4)C≡CC(6)H(2)(OMe)(2)C≡CC(6)H(4)C≡CRu(L(2))Cp'](2+), which on the basis of the spectroelectrochemical and computational results can be described in terms of two non-interacting Ru(C≡CAr)(L(2))Cp' moieties. X-ray structures of the oligophenyleneethynylene HC≡CC(6)H(4)C≡CC(6)H(2)(OMe)(2)C≡CC(6)H(4)C≡CH, the bis(gold) complex Ph(3)PAuC≡CC(6)H(4)C≡CC(6)H(2)(OMe)(2)C≡CC(6)H(4)C≡CAuPPh(3) and the precursor 1-ethynyl-4-(trimethylsilylethynyl)benzene are also reported.     

Organic triplet excited states of gold(I) complexes with oligo(o- or m-phenyleneethynylene) ligands: conjunction of steady-state and time-resolved spectroscopic studies on exciton delocalization and emission pathways

A series of mononuclear and binuclear gold(I) complexes containing oligo(o- or m-phenyleneethynylene) (PE) ligands, namely [PhC≡C(C(6)H(4)-1,2-C≡C)(n-1)Au(PCy(3))] (n = 2-4, 4a-c), [μ-{C≡C-(1,2-C(6)H(4)C≡C)(n)}{Au(PCy(3))}(2)] (n = 1-6, 8, 5a-g), [PhC≡C(C(6)H(4)-1,3-C≡C)(n-1)Au(PCy(3))] (n = 2-4, 6a-c), and [μ-{C≡C-(1,3-C(6)H(4)C≡C)(n)}{Au(PCy(3))}(2)] (n = 1, 2, 7a,b), were synthesized and structurally characterized. Extensive spectroscopic measurements have been performed by applying combined methods of femtosecond transient absorption (fs-TA), fs time-resolved fluorescence (fs-TRF), and nanosecond time-resolved emission (ns-TRE) coupled with steady-state absorption and emission spectroscopy at both ambient and low (77 K) temperatures to directly probe the temporal evolution of the excited states and to determine the dynamics and spectral signatures for the involved singlet (S(1)) and triplet (T(1)) excited states. The results reveal that S(1) and T(1) both feature ligand-centered electronic transitions with ππ* character associated with the phenyl and acetylene moieties. The (3)ππ* emission of the PE ligands is switched on by the attachment of [Au(PCy(3))](+) fragment(s) due to the heavy-atom effect. T(1)((3)ππ*) was found to form with nearly unity efficiency through intersystem crossing (ISC) from S(1)((1)ππ*). The ISC time constants were determined to be ～50, 35, and 40 ps for 4b and 6a,b, respectively. Dual emission composed of fluorescence from S(1) and phosphorescence from T(1) were observed for most of the complexes except 5a and 7a, where only phosphorescence was found. The fluorescence at ambient temperature is accounted for by both the short-lived prompt fluorescence (PF) and long-lived delayed fluorescence (DF, lifetime on microsecond time scale). Explicit evidence was presented for a triplet-triplet annihilation mechanism for the generation of DF. Ligand length and substitution-dependent dynamics of T(1) are the key factors governing the dual emission character of the complexes. By extrapolation from the plot of emission energy against the PE chain length of the [Au(PCy(3))](+) complexes with oligo(o-PE) or oligo(m-PE) ligands, the triplet emission energies were estimated to be ～530 and ～470 nm for poly(o-PE) and poly(m-PE), respectively. Additionally, we assign the unusual red shifts of 983 cm(-1) from [PhC≡CAu(PCy(3))] (1) to [μ-{1,3-(C≡C)(2)C(6)H(4)}{Au(PCy(3))}(2)] (7a) and 462 cm(-1) from 7a to [μ(3)-{1,3,5-(C≡C)(3)C(6)H(3)}{Au(PCy(3))}(3)] (8) in the phosphorescence energies to excitonic coupling interactions between the C≡CAu(PCy(3)) arms in the triplet excited states. These complexes, together with those previously reported [Au(PCy(3))](+) complexes containing oligo(p-PE) ligands ( J. Am. Chem. Soc. 2002 , 124 , 14696 - 14706 ), form a collection of oligo(phenyleneethynylene) complexes exhibiting organic triplet emission in solution under ambient conditions. The remarkable feature of these complexes in exhibiting TTA prompted DF in conjunction with high formation efficiency of T(1)((3)ππ*) affords an opportunity for emission spectra to cover a wide range of wavelengths. This may have implication in the development of PE-based molecular materials for future optical applications.     

Cyclopropenylidene carbene ligands in palladium catalysed coupling reactions: carbene ligand rotation and application to the Stille reaction

Reaction of [Pd(PPh(3))(4)] with 1,1-dichloro-2,3-diarylcyclopropenes gives complexes of the type cis-[PdCl(2)(PPh(3))(C(3)(Ar)(2))] (Ar = Ph 5, Mes 6). Reaction of [Pd(dba)(2)] with 1,1-dichloro-2,3-diarylcyclopropenes in benzene gave the corresponding binuclear palladium complexes trans-[PdCl(2)(C(3)(Ar)(2))](2) (Ar = Ph 7, p-(OMe)C(6)H(4)8, p-(F)C(6)H(4)9). Alternatively, when the reactions were performed in acetonitrile, the complexes trans-[PdCl(2)(NCMe)(C(3)(Ar)(2))] (Ar = Ph 10, p-(OMe)C(6)H(4)11 and p-(F)C(6)H(4)) 12) were isolated. Addition of phosphine ligands to the binuclear palladium complex 7 or acetonitrile adducts 11 and 12 gave complexes of the type cis-[PdCl(2)(PR(3))(C(3)(Ar)(2))] (Ar = Ph, R = Cy 13, Ar = p-(OMe)C(6)H(4), R = Ph 14, Ar = p-(F)C(6)H(4), R = Ph 15). Crystal structures of complexes 6·3.25CHCl(3), 10, 11·H(2)O and 12-15 are reported. DFT calculations of complexes 10-12 indicate the barrier to rotation about the carbene-palladium bond is very low, suggesting limited double bond character in these species. Complexes 5-9 were tested for catalytic activity in C-C coupling (Mizoroki-Heck, Suzuki-Miyaura and, for the first time, Stille reactions) and C-N coupling (Buchwald-Hartwig amination) showing excellent conversion with moderate to high selectivity.     

Syntheses of highly unsaturated isocyanides via organometallic pathways

The carbon carbon coupling reaction by nucleophilic attack of (CO)(5)Cr(CN-CF=CF(2)) 1 by lithium or Grignard compounds 2a-i yields the isocyanide complexes (CO)(5)Cr(CN-CF=CF-R) 3a-i (a R = CH=CH(2), b R = CH=CF(2), c R = C≡CH, d R = C≡C-SiMe(3), e R = C≡C-Ph, f R = C≡C-C(6)F(4)OMe, g R = C≡C-C(6)H(3)(CF(3))(2), h R = C(6)F(5), i R = C(6)H(3)(CF(3))(2)) as mixtures of E and Z isomers. The dinuclear complexes 5a-c are obtained from the reaction of 1 with the dilithio or dimagnesium compound 4a-c as the Z,Z-, E,Z- and E,E-isomers, respectively. (CO)(5)Cr(CN-CF=CF-C≡C-C≡C-CF=CF-NC)Cr(CO)(5)7 is obtained as a mixture of Z,Z-, Z,E- and E,E-isomers from (CO)(5)Cr(CN-CF=CF-C≡C-H 3d by Eglington-Glaser coupling. (CO)(5)Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)(5)6 and (CO)(5)Cr(CN-CF=CF-C=C-C≡C-CF=CF-NC)Cr(CO)(5)7 react with octacarbonyldicobalt forming the cluster compounds Z,Z-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)(5)}Co(2)(CO)(6)] Z,Z-8, E,Z-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)(5)}Co(2)(CO)(6)] E,Z-8 and E,E-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-CF=CF-NC)Cr(CO)(5)}Co(2)(CO)(6)] E,E-8 and Z,Z-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-C≡C-CF=CF-NC)Cr(CO)(5)}{Co(2)(CO)(6)}(2)] Z,Z-9, E,Z-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-C≡C-CF=CF-NC)Cr(CO)(5)}{Co(2)(CO)(6)}(2)] E,Z-9 and E,E-[{η(2)-μ(2)-(CO)(5)Cr(CN-CF=CF-C≡C-C≡C-CF=CF-NC)Cr(CO)(5)}{Co(2)(CO)(6)}(2)] Z,Z-9, respectively. The crystal and molecular structures of E-3d, Z-3h, Z,Z-8, E,Z-8 and Z,Z-9 were elucidated by single-crystal X-ray crystallography.     

(Fluoren-9-ylidene)methanedithiolato complexes of platinum: synthesis, reactivity, and luminescence

Platinum(II) complexes with (fluoren-9-ylidene)methanedithiolato and its 2,7-di-tert-butyl- and 2,7-dimethoxy-substituted analogues were obtained by reacting different chloroplatinum(II) precursors with the piperidinium dithioates (pipH)[(2,7-R2C12H6)CHCS2] [R = H (1a), t-Bu (1b), or OMe (1c)] in the presence of piperidine. The anionic complexes Q2[Pt{S(2)C=C(C12H6R(2)-2,7)}2] [R = H, (Pr(4)N)(2)2a; R = t-Bu, (Pr4N)(2)2b, (Et4N)(2)2b; R = OMe, (Pr4N)(2)2c] were prepared from PtCl(2), piperidine, the corresponding QCl salt, and 1a-c in molar ratio 1:2:2:2. In the absence of QCl, the complexes (pipH)(2)2b and [Pt(pip)(4)]2b were isolated depending on the PtCl(2):pip molar ratio. The neutral complexes [Pt{S2C=C(C12H6R(2)-2,7)L(2)] [L = PPh(3), R = H (3a), t-Bu (3b), OMe (3c); L = PEt(3), R = H (4a), t-Bu (4b), OMe (4c); L(2) = dbbpy, R = H (5a), t-Bu (5b), OMe (5c) (dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridyl)] were similarly prepared from the corresponding precursors [PtCl2L2] and 1a-c in the presence of piperidine. Oxidation of Q(2)2b with [FeCp2]PF6 afforded the mixed Pt(II)-Pt(IV) complex Q2[Pt2{S2C=C[C12H6(t-Bu)(2)-2,7]}4] (Q(2)6, Q = Et4N+, Pr4N+). The protonation of (Pr4N)(2)2b with 2 equiv of triflic acid gave the neutral dithioato complex [Pt2{S2CCH[C12H6(t-Bu)(2)-2,7]}4] (7). The same reaction in 1:1 molar ratio gave the mixed dithiolato/dithioato complex Pr4N[Pt{S2C=C[C12H6(t-Bu)(2)-2,7]}{S2CCH[C12H6(t-Bu)(2)-2,7]}] (Pr(4)N8) while the corresponding DMANH+ salt was obtained by treating 7 with 2 equiv of 1,8-bis(dimethylamino)naphthalene (DMAN). The crystal structures of 3b and 5c.CH2Cl2 have been solved by X-ray crystallography. All the platinum complexes are photoluminescent at 77 K in CH2Cl2 or KBr matrix, except for Q(2)6. Compounds 5a-c and Q8 show room-temperature luminescence in fluid solution. The electronic absorption and emission spectra of the dithiolato complexes reveal charge-transfer absorption and emission energies which are significantly lower than those of analogous platinum complexes with previously described 1,1-ethylenedithiolato ligands and in most cases compare well to those of 1,2-dithiolene complexes.     

Silver(I) Ethynide Coordination Networks and Clusters Assembled with tert-Butylphosphonic Acid

Variation of the reaction conditions with AgC≡CR (R = Ph, C(6)H(4)OCH(3)-4, (t)Bu), (t)BuPO(3)H(2), and AgX (X = NO(3), BF(4)) as starting materials afforded four new silver(I) ethynide complexes incorporating the tert-butylphosphonate ligand, namely, 3AgC≡CPh·Ag(2)(t)BuPO(3)·Ag(t)BuPO(3)H·2AgNO(3) (1), 2AgC≡CC(6)H(4)OCH(3)-4·Ag(2)(t)BuPO(3)·2AgNO(3) (2), [{Ag(5)(NO(3)@Ag(18))Ag(5)}((t)BuC≡C)(16)((t)BuPO(3))(4)(H(2)O)(3)][{Ag(5)(NO(3)@Ag(18))Ag(5)} ((t)BuC≡C)(16)((t)BuPO(3))(4)(H(2)O)(4)]·3SiF(6)·4.5H(2)O·3.5MeOH (3), and [{Ag(8)(Cl@Ag(14))}((t)BuC≡C)(14)((t)BuPO(3))(2)F(2)(H(2)O)(2)]BF(4)·3.5H(2)O (4). Single-crystal X-ray analysis revealed that complexes 1 and 2 display different layer-type coordination networks, while 3 and 4 contain high-nuclearity silver(I) composite clusters enclosing nitrate and chloride template ions, respectively, that are supported by (t)BuPO(3)(2-) ligands.     

Thermodynamics, kinetics, and mechanism of (silox)3M(olefin) to (silox)3M(alkylidene) rearrangements (silox = tBu3SiO; M = Nb, Ta)

Olefin complexes (silox)(3)M(ole) (silox = (t)Bu(3)SiO; M = Nb (1-ole), Ta (2-ole); ole = C(2)H(4), C(2)H(3)Me, C(2)H(3)Et, C(2)H(3)C(6)H(4)-p-X (X = OMe, H, CF(3)), C(2)H(3)(t)Bu, (c)C(5)H(8), (c)C(6)H(10), (c)C(7)H(10) (norbornene)) rearrange to alkylidene isomers (silox)(3)M(alk) (M = Nb (1=alk), Ta (2=alk); alk = CHMe, CHEt, CH(n)Pr, CHCH(2)C(6)H(4)-p-X (X = OMe, H, CF(3) (Ta only)), CHCH(2)(t)Bu, (c)C(5)H(8), (c)C(6)H(10), (c)C(7)H(10) (norbornylidene)). Kinetics and labeling experiments suggest that the rearrangement proceeds via a delta-abstraction on a silox CH bond by the beta-olefin carbon to give (silox)(2)RM(kappa(2)-O,C-OSi(t)Bu(2)CMe(2)CH(2)) (M = Nb (4-R), Ta (6-R); R = Me, Et, (n)Pr, (n)Bu, CH(2)CH(2)C(6)H(4)-p-X (X = OMe, H, CF(3) (Ta only)), CH(2)CH(2)(t)Bu, (c)C(5)H(9), (c)C(6)H(11), (c)C(7)H(11) (norbornyl)). A subsequent alpha-abstraction by the cylometalated "arm" of the intermediate on an alpha-CH bond of R generates the alkylidene 1=alk or 2=alk. Equilibrations of 1-ole with ole' to give 1-ole' and ole, and relevant calculations on 1-ole and 2-ole, permit interpretation of all relative ground and transition state energies for the complexes of either metal.     

Influence of the electronic characteristics of N-donor ligands in the excited state of heteronuclear gold(I)-copper(I) systems

By reaction of the heterometallic gold-silver complexes [{AuAg(C(6)F(5))(2)(N≡C-Me)}(2)](n) or [{AuAg(C(6)Cl(5))(2)(N≡C-Me)}(2)](n) and CuCl in the presence of pyrimidine and different nitrile ligands (acetonitrile, benzonitrile, and cinnamonitrile), the heteronuclear complexes {[Au(C(6)X(5))(2)][Cu(L)(μ(2)-C(4)H(4)N(2))]}(n) (X = F and L = N≡C-Me (1), L = N≡C-Ph (2) or N≡C-CH═CH-Ph (3); X = Cl and L = N≡C-Me (4), N≡C-Ph (5), N≡C-CH═CH-Ph (6)) have been prepared. The crystal structures of complexes {[Au(C(6)X(5))(2)][Cu(L)(μ(2)-C(4)H(4)N(2))]}(n) (X = F; L = N≡C-CH═CH-Ph (3), X = Cl; L = N≡C-Ph (5)) have been determined by X-ray diffraction studies. The crystal structures of both complexes consists of polymeric chains formed by the repetition of [Au(C(6)X(5))(2)][Cu(L)(μ(2)-C(4)H(4)N(2))] units through copper-pyrimidine bonds. Complexes 1, 2, 4, and 5 are brightly luminescent in the solid state at room temperature and at 77 K with lifetimes in the microseconds range. These compounds are also luminescent in solution, displaying different photophysical behaviors depending on the donor characteristics of the solvents used. The distortion in the excited state allows an associative attack by donor solvents quenching one of the emitting excited states. DFT optimizations of the ground (S(0)) and lowest triplet excited state (T(1)) display the structure distortion of the complexes upon electronic excitation. The molecular orbitals involved in the electronic transitions responsible for the phosphorescence in the case of the complexes 1, 2, 4, and 5 are related to metal (gold-copper) to ligand (pyrimidine) charge transfer transitions, while in the case of the nonluminescent complexes 3 and 6, the nonradiative electronic transition arises from metal (gold-copper) to ligand (cinnamonitrile) charge transfer transitions.     

New palladium-catalyzed cross-coupling routes to carbon functionalized metallatricarbadecaboranes

A general method for the synthesis of cage-carbon-functionalized cyclopentadienyl iron and cyclopentadienyl ruthenium tricarbadecaboranyl complexes has been developed that employs palladium-catalyzed Sonogashira, Heck, and Stille cross-coupling reactions directed at a cage-carbon haloaryl substituent. The key Li(+)[6-(p-XC(6)H(4))-nido-5,6,9-C(3)B(7)H(9)(-)] (X = I (1), Br (2), Cl (3)) haloaryl-tricarbadecaboranyl anionic ligands were synthesized in high yields via the reaction of the arachno-4,6-C(2)B(7)H(12)(-) anion with the corresponding p-halobenzonitriles (p-XC(6)H(4)-CN). The reactions of the salts 1-3 with (η(5)-C(5)H(5))Fe(CO)(2)I and (η(5)-C(5)H(5))Ru(CH(3)CN)(3)PF(6) were then used to produce the haloaryl complexes 1-(η(5)-C(5)H(5))-2-(p-XC(6)H(4))-closo-1,2,3,4-MC(3)B(7)H(9) (M = Fe, X = I (4), Br (5), Cl (6) and M = Ru, X = I (7), Br (8), Cl (9)). The sonication-promoted Sonogashira coupling reactions of 4 with terminal alkynes catalyzed by Pd(dppf)(2)Cl(2)/CuI yielded the alkynyl-linked derivatives 1-(η(5)-C(5)H(5))-2-p-RC(6)H(4)-closo-1,2,3,4-FeC(3)B(7)H(9) (R = (PhC≡C)- (10), (CH(3)CH(2)C(O)OCH(2)C≡C)- (11), ((η(5)-C(5)H(5))Fe(η(5)-C(5)H(4)C≡C))- (12)). Heck reactions of 4 with terminal alkenes catalyzed by Pd(OAc)(2) yielded the alkene-functionalized products 1-(η(5)-C(5)H(5))-2-p-RC(6)H(4)-closo-1,2,3,4-FeC(3)B(7)H(9) (R = (PhCH(2)CH═CH)- (13), (CH(3)(CH(2))(2)CH═CH)- (14)), while the Stille cross-coupling reactions of 4 with organotin compounds catalyzed by Pd(PPh(3))(2)Cl(2) afforded the complexes 1-(η(5)-C(5)H(5))-2-p-RC(6)H(4)-closo-1,2,3,4-FeC(3)B(7)H(9) (R = Ph- (15), (CH(2)═CH)- (16), (CH(2)═CHCH(2))- (17)). These reactions thus provide facile and systematic access to a wide variety of new types of functionalized metallatricarbadecaboranyl complexes with substituents needed for potential metallocene-like biomedical and/or optoelectronic applications.     

Tri- and tetracoordinate copper(I) complexes bearing bidentate soft/hard SN and SeN ligands based on 2-aminopyridine

The coordination properties of the EN ligands N-(2-pyridinyl)amino-diphenylphosphine sulfide, N-(2-pyridinyl)amino-diisopropylphosphine sulfide, N-(2-pyridinyl)amino-diphenylphosphine selenide, N-(2-pyridinyl)amino-diisopropylphosphine selenide towards copper(I) precursors CuX (X = Br, I), [Cu(IPr)Cl] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), and [Cu(CH(3)CN)(4)]PF(6) were studied. Treatment of CuX with EN ligands resulted in the formation of tricoordinate complexes of the type [Cu(κ(2)(E,N)-EN)X]. The reaction of [Cu(IPr)Cl] with EN ligands, followed by halide abstraction with AgSbF(6), afforded cationic tricoordinate complexes [Cu(κ(2)(S,N)-EN)(IPr)](+), while the reaction of [Cu(CH(3)CN)(4)](+) with two equivalents of EN ligands yielded tetrahedral complexes [Cu(κ(2)(E,N)-EN)(2)](+). Halide removal from [Cu(κ(2)(S,N)-SN)I] with silver salts in the presence of L = CH(3)CN and CNtBu afforded dinuclear complexes of the type [Cu(κ(2)(S,N),μ(S)-SN)(L)](2)(2+) containing bridging SN ligands. With the terminal alkynes HC≡CC(6)H(4)Me and HC≡CC(6)H(4)OMe, complexes of the formula [Cu(κ(2)(S,N)-SN-iPr)(η(2)-HC≡CC(6)H(4)Me)](+) and [Cu(κ(2)(S,N)-SN-iPr)(η(2)-HC≡CC(6)H(4)OMe)](+) were obtained. The mononuclear nature of these compounds was supported by DFT calculations. Most complexes were also characterized by X-ray crystallography.     

Structural and catalytic studies of lithium complexes bearing pendant aminophenolate ligands

Lithium complexes bearing mono-anionic aminophenolate ligands are described. Reactions of ligand precursors HON(Me)Ph(OMe), HON(Me)Ph(SMe), HON(Me)C(OMe) or HON(Me)C(NMe2) [HON(Me)Ph(OMe) = (2-OMeC6H4CH2)N(Me)(CH2-2-HO-3,5-C6H2((t)Bu)2); HON(Me)Ph(SMe)= (2-SMe-C6H4CH2)N(Me)(CH2-2-HO-3,5-C6H2((t)Bu)2); HON(Me)C(OMe) = (MeOCH(2)CH2)N(Me)(CH2-2-HO-3,5-C6H2((t)Bu)2); HON(Me)C(NMe2) = (Me2NCH2CH2)N(Me)(CH2-2-HO-3,5-C6H2((t)Bu)2)] with 1.1-1.3 molar equivalents of (n)BuLi in diethyl ether solution afford (LiON(Me)Ph(OMe))(2) (3), (LiON(Me)Ph(SMe))2 (4), (LiON(Me)C(OMe))2 (5) and (LiON(Me)C(NMe2))2 (6) as dinuclear lithium complexes. The BnOH adduct of , (BnOH)(LiON(Me)C(OMe)) (7), was prepared from the reaction of and BnOH in diethyl ether solution. The molecular structures are reported for ligand precursor HON(Me)Ph(SMe) and compounds 3-5 and 7. These dinuclear lithium complexes show excellent catalytic activities toward the ring-opening polymerization of L-lactide in the presence of benzyl alcohol.     

From tetrahydroborate- to aminoborylvinylidene-osmium complexes via alkynyl-aminoboryl intermediates

The tetrahydroborate OsH(η(2)-H(2)BH(2))(CO)(P(i)Pr(3))(2) (1) reacts with aniline and p-toluidine to give the aminoboryl derivatives [chemical structure: see text] (R = H (2), CH(3) (3)) and four H(2) molecules. Treatment of 2 and 3 with phenylacetylene gives Os{B(NHC(6)H(4)R)(2)}(C≡CPh)(CO)(P(i)Pr(3))(2) (R = H (4), CH(3) (5)), which react with HBF(4) to afford the amino(fluoro)boryl species Os{BF(NHC(6)H(4)R)}(C≡CPh)(CO)(P(i)Pr(3))(2) (R = H (6), CH(3) (7)). In contrast to HBF(4), the addition of acetic acid to 4 and 5 induces the release of phenylacetylene and the formation of the six-coordinate derivatives Os{B(NHC(6)H(4)R)(2)}(κ(2)-O(2)CCH(3))(CO)(P(i)Pr(3))(2) (R = H (8), CH(3) (9)). The coordination number six for 4 and 5 can be also achieved by addition of CO. Under this gas Os{B(NHC(6)H(4)R)(2)}(C≡CPh)(CO)(2)(P(i)Pr(3))(2) (R = H (10), CH(3) (11)) are formed. In toluene, these alkynyl-aminoboryl compounds evolve into the aminoborylvinylidenes Os{═C═C(Ph)B(NHC(6)H(4)R)(2)}(CO)(2)(P(i)Pr(3))(2) (R = H (12), CH(3) (13)) via a unimolecular 1,3-boryl migration from the metal to the C(β) atom of the alkynyl ligand. Similarly to 4 and 5, complexes 6 and 7 coordinate CO to give Os{BF(NHC(6)H(4)R)}(C≡CPh)(CO)(2)(P(i)Pr(3))(2) (R = H (15), CH(3) (16)), which evolve to Os{═C═C(Ph)BF(NHC(6)H(4)R)}(CO)(2)(P(i)Pr(3))(2) (R = H (17), CH(3) (18)).     

The metalla-Pinner reaction between Pt(IV)-bound nitriles and alkylated oxamic and oximic forms of hydroxamic acids

The nitrile ligands in the platinum(IV) complexes trans-[PtCl4(RCN)2] (R=Me, Et, CH2Ph) and cis/trans-[PtCl4(MeCN)(Me2SO)] are involved in a metalla-Pinner reaction with N-methylbenzohydroxamic acid (N-alkylated form of hydroxamic acid, hydroxamic form; F1), PhC(=O)N(Me)OH, to achieve the imino species [PtCl4[NH=C(R)ON(Me)C(=O)Ph]2 (1-3) and [PtCl4[NH=C(Me)ON(Me)C(=O)Ph](Me2SO)] (7), respectively. Treatment of trans-[PtCl4(RCN)2] (R=Me, Et) and cis/trans-[PtCl4(MeCN)(Me2SO)] with the O-alkylated form of a hydroxamic acid (hydroximic form), i.e. methyl 2,4,6-trimethylbenzohydroximate, 2,4,6-(Me3C6H2)C(OMe)=NOH (F2A), allows the isolation of [PtCl4[NH=C(R)ON=C(OMe)(2,4,6-Me3C6H2)]2] (5, 6) and [PtCl4[NH=C(Me)ON=C(OMe)(2,4,6-Me3C6H2)](Me2SO)] (8), correspondingly. In accord with the latter reaction, the coupling of nitriles in trans-[PtCl4(EtCN)2] with methyl benzohydroximate, PhC(OMe)=NOH (F2B), gives [PtCl4[NH=C(Et)ON=C(OMe)Ph]2] (4). The addition proceeds faster with the hydroximic F2, rather than with the hydroxamic form F1. The complexes 1-8 were characterized by C, H, N elemental analyses, FAB+ mass-spectrometry, IR, 1H and 13C[1H] NMR spectroscopies. The X-ray structure determinations have been performed for both hydroxamic and hydroximic complexes, i.e. 2 and 6, indicating that the imino ligands are mutually trans and they are in the E-configuration.     

Fully delocalized (ethynyl)(vinyl)phenylene bridged triruthenium complexes in up to five different oxidation states

Triruthenium [(dppe)(2)Ru{-C≡C-1,4-C(6)H(2)-2,5-R(2)-CH═CH-RuCl(CO)(P(i)Pr(3))(2)}(2)](n+) (4a, R = H; 4b, R = OMe) containing unsymmetrical (ethynyl)(vinyl)phenylene bridging ligands and displaying five well-separated redox states (n = 0-4) are compared to their bis(alkynyl)ruthenium precursors (dppe)(2)Ru{-C≡C-1,4-C(6)H(2)-2,5-R(2)-C≡CR'} (2a,b: R' = TMS; 3a,b: R' = H) and their symmetrically substituted bimetallic congeners, complexes {Cl(dppe)(2)Ru}(2){μ-C≡C-1,4-C(6)H(2)-2,5-R(2)-C≡C} (A(a), R = H; A(b), R = OMe) and {RuCl(CO)(P(i)Pr(3))(2)}(2){μ-CH═CH-1,4-C(6)H(2)-2,5-R(2)-CH═CH} (V(a), R = H; V(b), R = OMe) as well as the mixed (ethynyl)(vinyl)phenylene bridged [Cl(dppe)(2)Ru-C≡C-1,4-C(6)H(4)-CH═CH-RuCl(CO)(P(i)Pr(3))(2)] (M(a)). Successive one-electron transfer steps were studied by means of cyclic voltammetry, EPR and UV-vis-NIR-IR spectroelectrochemistry. These studies show that the first oxidation mainly involves the central bis(alkynyl) ruthenium moiety with only limited effects on the appended vinyl ruthenium moieties. The second to fourth oxidations (n = 2, 3, 4) involve the entire carbon-rich conjugated path of the molecule with an increased charge uniformly distributed between the two arms of the molecules, including the terminal vinyl ruthenium sites. In order to assess the charge distribution, we judiciously use (13)CO labeled analogues to distinguish stretching vibrations due to the acetylide triple bonds and the intense and charge-sensitive Ru(CO) IR probe in different oxidation states. The comparison between complex pairs 4a,b(n+) (n = 0-3), A(a,b)(n+) and V(a,b)(n+) (n = 0-2) serves to elucidate the effect of the methoxy donor substituents on the redox and spectroscopic properties of these systems in their various oxidation states and on the metal/ligand contributions to their frontier orbitals.     

Synthesis, reactivity studies, structural aspects, and solution behavior of half sandwich ruthenium(II) N,N',N'-triarylguanidinate complexes

[(η(6)-C(10)H(14))RuCl(μ-Cl)](2) (η(6)-C(10)H(14) = η(6)-p-cymene) was subjected to a bridge-splitting reaction with N,N',N'-triarylguanidines, (ArNH)(2)C═NAr, in toluene at ambient temperature to afford [(η(6)-C(10)H(14))RuCl{κ(2)(N,N')((ArN)(2)C-N(H)Ar)}] (Ar = C(6)H(4)Me-4 (1), C(6)H(4)(OMe)-2 (2), C(6)H(4)Me-2 (3), and C(6)H(3)Me(2)-2,4 (4)) in high yield with a view aimed at understanding the influence of substituent(s) on the aryl rings of the guanidine upon the solid-state structure, solution behavior, and reactivity pattern of the products. Complexes 1-3 upon reaction with NaN(3) in ethanol at ambient temperature afforded [(η(6)-C(10)H(14))RuN(3){κ(2)(N,N')((ArN)(2)C-N(H)Ar)}] (Ar = C(6)H(4)Me-4 (5), C(6)H(4)(OMe)-2 (6), and C(6)H(4)Me-2 (7)) in high yield. [3 + 2] cycloaddition reaction of 5-7 with RO(O)C-C≡C-C(O)OR (R = Et (DEAD) and Me (DMAD)) (diethylacetylenedicarboxylate, DEAD; dimethylacetylenedicarboxylate, DMAD) in CH(2)Cl(2) at ambient temperature afforded [(η(6)-C(10)H(14))Ru{N(3)C(2)(C(O)OR)(2)}{κ(2)(N,N')((ArN)(2)C-N(H)Ar)}]·xH(2)O (x = 1, R = Et, Ar = C(6)H(4)Me-4 (8·H(2)O); x = 0, R = Me, Ar = C(6)H(4)(OMe)-2 (9), and C(6)H(4)Me-2 (10)) in moderate yield. The molecular structures of 1-6, 8·H(2)O, and 10 were determined by single crystal X-ray diffraction data. The ruthenium atom in the aforementioned complexes revealed pseudo octahedral "three legged piano stool" geometry. The guanidinate ligand in 2, 3, and 6 revealed syn-syn conformation and that in 4, and 10 revealed syn-anti conformation, and the conformational difference was rationalized on the basis of subtle differences in the stereochemistry of the coordinated nitrogen atoms caused by the aryl moiety in 3 and 4 or steric overload caused by the substituents around the ruthenium atom in 10. The bonding pattern of the CN(3) unit of the guanidinate ligand in the new complexes was explained by invoking n-π conjugation involving the interaction of the NHAr/N(coord)Ar lone pair with C═Nπ* orbital of the imine unit. Complexes 1, 2, 5, 6, 8·H(2)O, and 9 were shown to exist as a single isomer in solution as revealed by NMR data, and this was ascribed to a fast C-N(H)Ar bond rotation caused by a less bulky aryl moiety in these complexes. In contrast, 3 and 10 were shown to exist as a mixture of three and five isomers in about 1:1:1 and 1·0:1·2:2·7:3·5:6·9 ratios, respectively in solution as revealed by a VT (1)H NMR, (1)H-(1)H COSY in conjunction with DEPT-90 (13)C NMR data measured at 233 K in the case of 3. The multiple number of isomers in solution was ascribed to the restricted C-N(H)(o-tolyl) bond rotation caused by the bulky o-tolyl substituent in 3 or the aforementioned restricted C-NH(o-tolyl) bond rotation as well as the restricted ruthenium-arene(centroid) bond rotation caused by the substituents around the ruthenium atom in 10.     

Dual luminescent tetranuclear organogold(I) macrocycles of 5,5'-diethynyl-2,2'-bipyridine and their efficient sensitization of Yb(III) luminescence

Reaction of (AuC≡CbpyC≡CAu)(n) (HC≡CbpyC≡CH = 5,5'-diethynyl-2,2'-bipyridine) with diphosphine ligands Ph(2)P(CH(2))(n)PPh(2) (n = 1 dppm, 3 dppp, 5 dpppen, 6 dpph), 1,1'-bis(diphenylphosphino)ferrocene (dppf), and 1,2-bis(diphenylphosphino)benzene (bdpp) in CH(2)Cl(2) afforded the corresponding dual luminescent gold(I) complexes [(AuC≡CbpyC≡CAu)(2)(μ-dppm)(2)] (1), [(AuC≡CbpyC≡CAu)(2)(μ-dppp)(2)] (2), [(AuC≡CbpyC≡CAu)(2)(μ-dpppen)(2)] (3), [(AuC≡CbpyC≡CAu)(2)(μ-dpph)(2)] (4), [(AuC≡CbpyC≡CAu)(2)(μ-dppf)(2)] (5), and [(AuC≡CbpyC≡CAu)(2)(μ-bdpp)(2)] (6). The solid structures of complexes 1 and 2 are confirmed to be tetranuclear macrocyclic rings by single crystal structure analysis, and those of complexes 3-6 are proposed to be similar to those of complexes 1 and 2 in structure because their good solubility in CH(2)Cl(2), their HRMS results, and the P···P separations of 20.405-20.697 ? in the same linear rigid P-Au-C≡CbpyC≡C-Au-P unit are all favorable to form such 2:4:2 macrocycles. Each of the absorption spectral titrations between complexes 1-6 and Yb(hfac)(3)(H(2)O)(2) (Hhfac = hexafluoroacetylacetone) gives a 2:1 ratio between the Yb(hfac)(3) unit and the complex 1-6 moieties. The energy transfer occurs efficiently from the gold(I) alkynyl antennas 1-6 to Yb(III) centers with the donor ability in the order of 1 ~ 2 ~ 3 ~ 4 > 6 > 5.     

Synthesis, spectroscopy and electronic structure of the vinylidene and alkynyl complexes [W(C=CHR)(dppe)(η-C₇H₇)](+) and [W(C≡CR)(dppe)(η-C₇H₇](n+) (n = 0 or 1)

The first examples of vinylidene complexes of the cycloheptatrienyl tungsten system [W(C=CHR)(dppe)(η-C?H?)](+) (dppe = Ph?PCH?CH?PPh?; R = H, 3; Ph, 4; C?H?-4-Me, 5) have been synthesised by reaction of [WBr(dppe)(η-C?H?)], 1, with terminal alkynes HC≡CR; a one-pot synthesis of 1 from [WBr(CO)?(η-C?H?)] facilitates its use as a precursor. The X-ray structure of 4[PF?] reveals that the vinylidene ligand substituents lie in the pseudo mirror plane of the W(dppe)(η-C?H?) auxiliary (vertical orientation) with the phenyl group located syn to the cycloheptatrienyl ring. Variable temperature 1H NMR investigations on [W(C=CH?)(dppe)(η-C?H?)][PF?], 3, estimate the energy barrier to rotation about the W=C(α) bond as 62.5 ± 2 kJ mol?1; approximately 10 kJ mol?1 greater than for the molybdenum analogue. Deprotonation of 4 and 5 with KOBu(t) yields the alkynyls [W(C≡CR)(dppe)(η-C?H?)] (R = Ph, 6; C?H?-4-Me, 7) which undergo a reversible one-electron oxidation at a glassy carbon electrode in CH?Cl? with E(?) values approximately 0.12 V negative of Mo analogues. The 17-electron radicals [6](+) and [7](+) have been investigated by spectroelectrochemical IR, UV-visible and EPR methods. The electronic structures of representative vinylidene (3) and alkynyl (6) complexes have been investigated at the B3LYP/Def2-SVP level. In both cases, electronic structure is characterised by a frontier orbital with significant metal d(z2)character and this dominates the structural and spectroscopic properties of the system.     

Binuclear (salen)osmium phosphinidine and phosphiniminato complexes

The preparation of a number of binuclear (salen)osmium phosphinidine and phosphiniminato complexes using various strategies are described. Treatment of [Os(VI)(N)(L(1))(sol)](X) (sol = H(2)O or MeOH) with PPh(3) affords an osmium(IV) phosphinidine complex [Os(IV){N(H)PPh(3)}(L(1))(OMe)](X) (X = PF(6)1a, ClO(4)1b). If the reaction is carried out in CH(2)Cl(2) in the presence of excess pyrazine the osmium(III) phosphinidine species [Os(III){N(H)PPh(3)}(L(1))(pz)](PF(6)) 2 can be generated. On the other hand, if the reaction is carried out in CH(2)Cl(2) in the presence of a small amount of H(2)O, a μ-oxo osmium(IV) phosphinidine complex is obtained, [(L(1)){PPh(3)N(H)}Os(IV)-O-Os(IV){N(H)PPh(3)}(L(1))](PF(6))(2)3. Furthermore, if the reaction of [Os(VI)(N)(L(1))(OH(2))]PF(6) with PPh(3) is done in the presence of 2, the μ-pyrazine species, [(L(1)){PPh(3)N(H)}Os(III)-pz-Os(III){N(H)PPh(3)}(L(1))](PF(6))(2)4 can be isolated. Novel binuclear osmium(IV) complexes can be prepared by the use of a diphosphine ligand to attack two Os(VI)≡N. Reaction of [Os(VI)(N)(L(1))(OH(2))](PF(6)) with PPh(2)-C≡C-PPh(2) or PPh(2)-(CH(2))(3)-PPh(2) in MeOH affords the binuclear complexes [(MeO)(L(1))Os(IV){N(H)PPh(2)-R-PPh(2)N(H)}Os(IV)(L(1))(OMe)](PF(6))(2) (R = C≡C 5, (CH(2))(3)6). Reaction of [Os(VI)(N)(L(2))Cl] with PPh(2)FcPPh(2) generates a novel trimetallic complex, [Cl(L(2))Os(IV){NPPh(2)-Fc-PPh(2)N}Os(IV)(L(2))Cl] 7. The structures of 1b, 2, 3, 4, 5 and 7 have been determined by X-ray crystallography.     

含碳硼烷半夹心型钴硫16电子化合物与二炔烃的反应性研究

含双硫取代碳硼烷二齿配体的半夹心型钴16电子化合物CpCo[S2C2(B10H10)](Co16e)分别与1,4-二乙炔基苯(L1)、(S)-2,2′-二乙酰氧基-6,6′-二乙炔基-1,1′-联萘(L2)、2-溴-5-乙炔基噻吩(L3)和2,5-二乙炔基噻吩(L4)反应,分别得到18电子单核化合物CpCo(S2C2B10H9)(H2CCPhC≡CH)(1),CpCo(S2C2B10H9)[H2CC(C24H16O4)C≡CH](2),CpCo(S2C2B10H9)[H2CC(C4H2S)Br](3),和CpCo(S2C2B10H9)[H2CC(C4H2S)C≡CH](4)。化合物1～4的结构中都发生了金属诱导B-H键活化并生成了新的C-B键。在Co16e与L4的反应中,还得到了两分子炔烃以头对头二聚插入到金属中心的18电子化合物CpCo(S2C2B10H9)[HC≡C(C4H2S)C=CH-CH=C(C4H2S)C≡CH](5)。上述化合物通过NMR、IR、MS、元素分析等方法进行表征。     

Synthesis of 2- and 2,7-functionalized pyrene derivatives: an application of selective C-H borylation

An efficient synthetic route to 2- and 2,7-substituted pyrenes is described. The regiospecific direct C-H borylation of pyrene with an iridium-based catalyst, prepared in situ by the reaction of [{Ir(μ-OMe)cod}(2)] (cod = 1,5-cyclooctadiene) with 4,4'-di-tert-butyl-2,2'-bipyridine, gives 2,7-bis(Bpin)pyrene (1) and 2-(Bpin)pyrene (2, pin = OCMe(2)CMe(2)O). From 1, by simple derivatization strategies, we synthesized 2,7-bis(R)-pyrenes with R = BF(3)K (3), Br (4), OH (5), B(OH)(2) (6), and OTf (7). Using these nominally nucleophilic and electrophilic derivatives as coupling partners in Suzuki-Miyaura, Sonogashira, and Buchwald-Hartwig cross-coupling reactions, we obtained 2,7-bis(R)-pyrenes with R = (4-CO(2)C(8)H(17))C(6)H(4) (8), Ph (9), C≡CPh (10), C≡C[{4-B(Mes)(2)}C(6)H(4)] (11), C≡CTMS (12), C≡C[(4-NMe(2))C(6)H(4)] (14), C≡CH (15), N(Ph)[(4-OMe)C(6)H(4)] (16), and R = OTf, R' = C≡CTMS (13). Lithiation of 4, followed by reaction with CO(2), yielded pyrene-2,7-dicarboxylic acid (17), whilst borylation of 2-tBu-pyrene gave 2-tBu-7-Bpin-pyrene (18) selectively. By similar routes (including Negishi cross-coupling reactions), monosubstituted 2-R-pyrenes with R = BF(3)K (19), Br (20), OH (21), B(OH)(2) (22), [4-B(Mes)(2)]C(6)H(4) (23), B(Mes)(2) (24), OTf (25), C≡CPh (26), C≡CTMS (27), (4-CO(2)Me)C(6)H(4) (28), C≡CH (29), C(3)H(6)CO(2)Me (30), OC(3)H(6)CO(2)Me (31), C(3)H(6)CO(2)H (32), OC(3)H(6)CO(2)H (33), and O(CH(2))(12)Br (34) were obtained from 2. These derivatives are of synthetic and photophysical interest because they contain donor, acceptor, and conjugated substituents. The crystal structures of compounds 4, 5, 7, 12, 18, 19, 21, 23, 26, and 28-31 have also been obtained from single-crystal X-ray diffraction data, revealing a diversity of packing modes, which are described in the Supporting Information. A detailed discussion of the structures of 1 and 2, their polymorphs, solvates, and co-crystals is reported separately.