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Reaction of cis-Ru(~2-OAc) _2(PPh _3) _2 with two-electron donor ligands L results in the formation of complexes trans-[Ru(~1-OAc)(~2-OAc)L(PPh _3) _2] (L = CO, NO ~+, CNtBu). Vinylidene complexes (L = C=CHR) may be prepared from ...
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Reaction of cis-Ru(~2-OAc) _2(PPh _3) _2 with two-electron donor ligands L results in the formation of complexes trans-[Ru(~1-OAc)(~2-OAc)L(PPh _3) _2] (L = CO, NO ~+, CNtBu). Vinylidene complexes (L = C=CHR) may be prepared from the corresponding reaction with terminal alkynes HC=CR, and species containing hydroxyvinylidene ligands (L = C=CHCR ~1R ~2{OH}) may be prepared from related reactions with propargyl alcohols HC=CCR ~1R ~2{OH}. Treatment of cis-Ru(κ ~2- OAc) _2(PPh _3) _2 with ω-alkynols HC=C(CH _2) _nOH (n = 2-4) results in the formation of oxacyclocarbene complexes [L = CCH _2(CH _2) _nO]. An analysis of the spectroscopic data and the structural metrics (as determined by X-ray crystallography) of this series of complexes allows for the relative donor/acceptor properties of the ligand L to be evaluated. This comparison indicates that the vinylidene ligand behaves in a similar fashion to the isocyanide ligand. The complex cis-[Ru(~2-OAc) _2(PPh _3) _2] acts as a precursor for the formation of the complexes trans-[Ru(~1-OAc)(~2-OAc)L(PPh _3) _2] where L is a two-electron donor, σ-donor/π-acceptor ligand. The structural and spectroscopic data of these species provide insight into the relative electron demand of the ligands L.
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In order to improve the encapsulation of metal ions coordinated by tris(thioimidazolyl)borate ligands,four new such ligands with o-substituted phenyl substituents were synthe-sised as well as ones with p-tolyl and cyclohexyl subst...
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In order to improve the encapsulation of metal ions coordinated by tris(thioimidazolyl)borate ligands,four new such ligands with o-substituted phenyl substituents were synthe-sised as well as ones with p-tolyl and cyclohexyl substituents.In order to provide a basis for their bioinorganic zinc complex chemistry,they were converted to some zinc-halide,-carbox-ylate,-nitrate,-phenolate and -benzylate complexes.They form zinc-perchlorate complexes which are productive starting materials for the attachment of alcohols and alkoxides at zinc,thereby yielding new structural models for the zinc enzyme alcohol dehydrogenase.
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Evaluation of the acidity of proton-responsive ligands such as protic N-heterocyclic carbenes (NHCs) bearing an NH-wingtip provides a key to understanding the metal-ligand cooperation in enzymatic and artificial catalysis. Here, w...
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Evaluation of the acidity of proton-responsive ligands such as protic N-heterocyclic carbenes (NHCs) bearing an NH-wingtip provides a key to understanding the metal-ligand cooperation in enzymatic and artificial catalysis. Here, we design a CNN pincer-type ruthenium complex 2 bearing protic NHC and isoelectronic pyrazole units in a symmetrical skeleton, to compare their acidities and electron-donating abilities. The synthesis is achieved by direct C-H metalation of 2-(imidazol-1-yl)-6-(pyrazol-3-yl)pyridine with [RuCl2(PPh3)(3)]. N-15-Labeling experiments confirm that deprotonation of 2 occurs first at the pyrazole side, indicating clearly that the protic pyrazole is more acidic than the NHC group. The electrochemical measurements as well as derivatization to carbonyl complexes demonstrate that the protic NHC is more electron-donating than pyrazole in both protonated and deprotonated forms.
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Two novel trinuclear tin oxo clusters [(C_2S_3N_2)R_6Sn_3O-(OH)Y] centre dot L [R=CH_3,Y=OH,L=1 centre dot 5H_2O (1);R=PhCH_2,Y=OEt,L=0 (2)],a pentanuclear tin macrocycle [(CH_3)_2Sn (C_2N_2S_3)]_5 centre dot CH_2C1_2 centre dot 3...
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Two novel trinuclear tin oxo clusters [(C_2S_3N_2)R_6Sn_3O-(OH)Y] centre dot L [R=CH_3,Y=OH,L=1 centre dot 5H_2O (1);R=PhCH_2,Y=OEt,L=0 (2)],a pentanuclear tin macrocycle [(CH_3)_2Sn (C_2N_2S_3)]_5 centre dot CH_2C1_2 centre dot 3H_2O (3) and [(PhCH_2)_4Cl_2Sn(C_2S_3N_2)] (4) have been synthesized by the reaction of 2,5-dimercapto-1,3,4-thiadiazole with dialkyltin dichloride in ethanol (95%) or dichloromethane.Complexes 1-4 have been characterized by elemental analysis and IR,~1H,~(13)C and ~(119)Sn NMR spec-troscopy.The structures of 1-3 have been determined by X-ray crystallography.Complexes 1 and 2 display a unique tricyclic structure consisting of fused five-membered Sn_2ON_2 and four-membered Sn_2O_2 rings that form a planar N_2Sn_3O_2 skeleton,with a distorted trigonal bipyramidal coordination at tin.Complex 3 is a pentanuclear 35-membered tin macro-cycle containing the crown thioether-type ligand in which all five tin atoms bond to the sulfur and nitrogen atoms with distorted octahedral geometries.The structures of complexes 1 and 3 are stabilized by hydrogen bonds or intermolecular non-bonding S-S interactions.
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The synthesis of new tripodal nitrogen ligands derived from tris(pyrazolyl)methane (Tpm R, R = H, tBu, Ph in 3-position) is described. After deprotonation of the parent tris(pyrazolyl)methane Tpm(R), the carbanion reacts readily w...
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The synthesis of new tripodal nitrogen ligands derived from tris(pyrazolyl)methane (Tpm R, R = H, tBu, Ph in 3-position) is described. After deprotonation of the parent tris(pyrazolyl)methane Tpm(R), the carbanion reacts readily with ethylene oxide to ligands yield the 3,.3,3-tris(3'-substituted pyrazolyl)propanol [(3-Rpz)(3)CCH2CH2OH, R = H, tBu, Ph, 1a-c]. These ligands can be easily derivatised at the alcohol function. Microwave-assisted reactions of these ligands and [Re(CO)(5)Br] yields the complex [(1a)Re(CO)(3)]Br (4) in the case of ligand la, whereas in the case of the substituted ligands 1b and 1c degradation was observed. The degradation products are identified as [(Hpz(R))(2)Re(CO)(3)Br] [R = tBu (7b), Ph (7c)]. These complexes were also prepared directly from [Re(CO)5Br] and the corresponding pyrazoles by microwave-assisted synthesis. The Re(CO)3 complexes 4 and [(1a)Re(CO)(3)]OTf (5) are water-soluble. The structures of 5-HO and [{(pz)(3)CCH2Cu3}Re(CO)(3)]OTf center dot 1.5H(2)O.1/2CH(3)CN (6 center dot 1.5H(2)O1/2CH(3)CN) as well as the structure of 7b have been elucidated by X-ray crystallography.
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The phosphine double exchange process involving [RhCl(COD)(TPP)] and [Rh(acac)(CO)(TMOPP)] (TPP = PPh3, TMOPP = P(C_6H_4-4-OMe)3) to yield [RhCl(COD)(TMOPP)] and [Rh(acac)(CO)(TPP)] is very rapid but is followed by a much slower p...
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The phosphine double exchange process involving [RhCl(COD)(TPP)] and [Rh(acac)(CO)(TMOPP)] (TPP = PPh3, TMOPP = P(C_6H_4-4-OMe)3) to yield [RhCl(COD)(TMOPP)] and [Rh(acac)(CO)(TPP)] is very rapid but is followed by a much slower process where the bidentate ligands are exchanged to yield [Rh(acac)(COD)] and a mixture of [RhCl(CO)(TPP)_2], [RhCl(CO)(TMOPP)_2], and [RhCl(CO)- (TPP)(TMOPP)]. The exchange involving [RhCl(COD)(L)] and [Rh(acac)(CO)(L)] yields [Rh(acac)(COD)] and [RhCl(CO)(L)_2], where the reaction is much faster when L = TPP than when L = TMOPP. The mixed-metal system comprising [IrCl(COD)(TPP)] and [Rh(acac)(CO)(TPP)] yields all four complexes [M(acac)(COD)] and [MCl(CO)(TPP)_2], where M = Rh and Ir. This illustrates that both a neutral ligand exchange and an anionic ligand exchange occur. Possible pathways for these processes are discussed.
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Treatment of the chloro(fulvalene)zirconium(III) compound [Zr(η~5-C_5H_5)(μ-Cl)]_2[μ-(η~5,η~5-C_(10)H_8)] with an equimolar amount of azobenzene in toluene, under extremely anhydrous conditions, gives the μ-[bis(imido)] deri...
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Treatment of the chloro(fulvalene)zirconium(III) compound [Zr(η~5-C_5H_5)(μ-Cl)]_2[μ-(η~5,η~5-C_(10)H_8)] with an equimolar amount of azobenzene in toluene, under extremely anhydrous conditions, gives the μ-[bis(imido)] derivative [Zr(η~5-C_5H_5)(μ-NPh)]_2[μ-(η~5,η~5-C_(10)H_8)] (1). However, when this reaction is carried out under insufficiently dry conditions a mixture of the previously reported μ-oxo complex [Zr(η~5-C_5H_5)Cl]_2(μ-O)[μ-(η~5,η~5-C_(10)H_8)] and 1,2-diphenylhydrazine is obtained. when the chloro(fulvalene)zirconium(III) compound reacts with benzo[c]cinnoline the μ-(η~2,η~2-N,N-hydrazido) complex [Zr(η~5-C_5H_5)Cl]_2[μ-(NC_6H_4C_6H_4N)][μ-(η~5,η~5-C_(10)H_8)] (2a) is obtained, which rearranges to the thermodynamically more stable 2b. Addition of an equimolar amount of RNC (R = nBu, C_6H_(11)) to a toluene solution of [Zr(η~5-C_5H_5)(μ-Cl)]_2[μ-(η~5,η~5-C_(10)H_8)] gives [Zr(η~5-C_5H_5)Cl]_2(μ-CNR)[μ-CNR)[μ-(η~5,η~5-C_(10)H_8)] [R = nBu (3), C_6H_(11) (4)]. Reaction of [Zr(η~5-C_5H_5)Cl]_2(μ-CNtBu)[μ-CNtBu)[μ-(η~5,η~5-C_(10)H_8)] with 1 equiv. of PhCH_2)_2Mg(THF)_2 afforded the monobenzyl derivatives [Zr(η~5-C_5H_5)]_2(CH_2Ph)(Cl)(μ-CNtBu)[μ-(η~5,η~5-C_(10)H_8)] (5 and 6). When this reaction was carried out with 2 equiv. or an excess of PhCH_2MgCl, a mixture of the monobenzyl and dibenzyl compounds [Zr(η~5-C_5H_5)]_2(CH_2Ph)(Cl)(μ-CNtBu)[μ-(η~5,η~5-C_(10)H_8)] (5) and [Zr(η~5-C_5H_5)(CH_2Ph)]_2(μ-CNtBu)[μ-CNtBu)[μ-(η~5,η~5-C_(10)H_8)] (7) is obtained. Similar reactions with 1 or 2 equiv. of (CH_3)_3SiCH_2Li afford a mixture of the monoalkyl and dialkyl compounds [Zr(η~5-C_5H_5)]_2[CH_2Si(CH_3)_3](Cl)(μ-CNtBu)[μ-(η~5,η~5-C_(10)H_8)] (8) and {Zr(η~5-C_5H_5)[CH_2Si(CH_3)_3]}_2(μ-CNtBu)[μ-(η~5,η~5-C_(10)H_8)] (9) compounds. Moreover, methylation of [Zr(η~5-C_5H_5)Cl]_2(μ-CNnBu)[μ-(η~5,η~5-C_(10)H_8)] gives the analytically pure tetramethyl derivative [Zr(η~5-C_5H_5)(CH_3)]_2(μ-CNnBu)[μ-(η~5,η~5-C_(10)H_8)] (10), whereas [Zr(η~5-C_5H_5)Cl]_2(μ-CNC_6H_(11))[μ-(η~5,η~5-C_(10)H_8)] reacts with MeLi to give a mixture of the monomethyl derivatives [Zr(η~5-C_5H_5)]_2(CH_3)(Cl)(μ-CNC_6H_(11)[μ-(η~5,η~5-C_(10)H_8)] (11 and 12), as well as the dimethyl compound [Zr(η~5-C_5H_5)(CH_3)]_2(μ-CNC_6H_(11))[μ-(η~5,η~5-C_(10)H_8)] (13).
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Until recently,tertiary phosphanes,arsanes,and stibanes were considered to bind to transition-metal centers only in a terminal coordiantion model.Investigations on the reactivity of square-planar trans-[RhCl(=CRR')(L)_2] compounds...
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Until recently,tertiary phosphanes,arsanes,and stibanes were considered to bind to transition-metal centers only in a terminal coordiantion model.Investigations on the reactivity of square-planar trans-[RhCl(=CRR')(L)_2] compounds revealed that compounds in which L=SbiPr_3 can be converted upon heating into dinculearcomplexes [Rh_2Cl_2(mu-CRR')_2(mu-SbiPr_3)]with the carbene and stibane ligands in bridging positions.Although attempts to replace the stibne in these complexes with a tertiary arsane or phosphane failed,substitution of the chloro ligands ofr acetylacetonates followed by bridge-ligand excahnge allowed the preapration of the chloro ligands for acetylacetonates follwed by bridge-ligand exchange allowed the preparation of the phosphane-and arsane-bridged compounds [Rh_2(acac)_2(mu-CRR')_2(mu-PR_3)]and [Rh_2(acac)_2(mu-CRR')_2(mu-AsMe_3)].The acac ligands can be replaced by anionic Lewis bases to give either monomeric [Rh_2X_2(mu-CRR')_2(mu-ER_3)] or dimeric chain-like [XRh(mu-CRR')_2(mu-ER_3)Rh(mu-X)_2Rh(mu-CRR')_2(mu-ER_3)RhX] molecules.
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The product of the reaction between tetramethylthiourea (tmtu) and cis-Pt~(II)(phos)_2 moieties (phos = PPh_3,or 1/2 dppe) depends on the anionic species present.With NO_3~-,CF_3CO_2~-,CF_3SO_3~- and BF_4~-,the cyclometallate cati...
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The product of the reaction between tetramethylthiourea (tmtu) and cis-Pt~(II)(phos)_2 moieties (phos = PPh_3,or 1/2 dppe) depends on the anionic species present.With NO_3~-,CF_3CO_2~-,CF_3SO_3~- and BF_4~-,the cyclometallate cationic complex [Pt(phos)_2(tmtu*-C,S)]~+ is obtained (tmtu* is tmtu deproton-ated at one methyl group).The acetato and malonato complexes are inactive towards such deprotonation,but,in the presence of water,promote tmtu hydrolysis with formation of N-dimethylmonothiocarbamato (mtc) complexes in which mtc is S-coordinated.cis-[Pt(PPh_3)_2(mtc)_2] isomerises slowly to the trans isomer,whose crystal structure is reported.
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The tridentate dianionic ligand 2-[2'-(hydroxyisopropoxyphos-phoryl)phenylsulfanyl]benzoate(L~(2-))reacts with cis-[Pt(NH3)2(H2O)2]~(2+)to form an S,O-chelate in which the O-co-ordinated group is either carboxylate or phosphonate,...
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The tridentate dianionic ligand 2-[2'-(hydroxyisopropoxyphos-phoryl)phenylsulfanyl]benzoate(L~(2-))reacts with cis-[Pt(NH3)2(H2O)2]~(2+)to form an S,O-chelate in which the O-co-ordinated group is either carboxylate or phosphonate,depending on the degree of protonation of the complex.Carboxylate appears to be the stronger ligand,and the stoichiometric reaction between cis-[Pt(NH3)2(H2O)2]~(2+)and L~(2-)yields the neutral species [Pt(L)-(NH3)2],with L bound by sulfanyl and carboxylate groups,both in solution and in the solid state.Upon protonation of [Pt(L)(NH3)2],the stronger basicity of the carboxylate causes the Pt coordination to switch from carboxylate to phosphonate,and the uncoordinated carboxylate group becomes pro-tonated.In methanolic solution,the first-order kinetics of this rearrange- ment could be observed by ~(31)P NMR spectroscopy.Both complexes-the car- boxylate-bound neutral complex [Pt(L)(NH3)2]·H2O(triclinic,P1 (no.2),a = 9.529(6),b = 9.766(6),c = 12.299(7)A,alpha = 106.91(2),beta = 101.71(2),gamma = 102.05(2)°,Z=2)and the perchlorate salt of the phosphonate- bound complex [Pt(LH)-(NH3)2]ClO_4 ·H2O(monoclinic,PZ_1/c(no.14),a = 12.095(2),b = 14.046(2),c= 14.448(2)A,beta = 95.55(2)°,Z=4)- were characterized by X-ray crystallography.
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