含半夹心结构铑的1,1'-二硫(硒、碲)二茂铁化合物

以半夹心结构铑的化合物Cp*Rh(CN^tBu)Cl2(1)(Cp*=η^5-C5Me5)与Fe(C5H4ELi)2.2THF反应,合成出异双核二茂铁化合物Cp*Rh(CN^tBu)(EC5H4)2Fe[E=S(2),Se(3),Te(4)]。通过AgBF4氧化2和3得到二茂铁离子型化合物[Cp*Rh(CN^tBu)(EC5H4)2Fe]BF4[E=S(5),Se(6)]。采用元素分析、红外光谱、^1H和13CNMR谱以及EI-MS表征了所合成的化合物。     

Enantiomerically pure rhodium complexes bearing 1,5-diphenyl-1,5-cyclooctadiene as a chiral diene ligand. Their use as catalysts for asymmetric 1,4-addition of phenylzinc chloride

[reaction and structures: see text] A rhodium complex coordinated with 1,5-diphenyl-1,5-cyclooctadiene (Ph-cod), [RhCl((R)-Ph-cod)]2, was obtained enantiomerically pure through optical resolution of diastereomeric isomers [Rh(Ph-cod)((R)-1,1'-binaphthyl-2,2'-diamine)]BF4. The enantiomerically pure rhodium complexes showed high catalytic activity and enantioselectivity (up to 98% ee) in the asymmetric 1,4-addition of phenylzinc chloride to alpha,beta-unsaturated ketones and esters in the presence of chlorotrimethylsilane.     

New ligand systems incorporating two and three 4,4'-bipyridine units. Characterization of bi- and trimetallic rhodium and iridium complexes

The synthesis of new ligand systems based on the bipyridine unit for bi- and trimetallic complexes, including a rare example of a chiral bimetallic complex, is presented. Ligands BBPX (bis-bipyridine-xylene, 3) and TBPBX (tris-bipyridine-bis-xylene, 4) were prepared in one step by reacting alpha,alpha'-dibromo-o-xylene (2) with 2 equiv of the monolithiated derivative of 4,4'-dimethyl-2,2'-bipyridine. Dilithium (S)-binaphtholate (5) reacted with 2 equiv of 4-bromomethyl-4'-methyl-2,2'-bipyridine (6), affording ligand (S)-BBPBINAP (bis-bipyridine-binaphtholate, 7). These ligands reacted cleanly with 1, 1.5, and 1 equiv of the rhodium dimer [Rh(2)Cl(2)(HD)(2)] (HD = 1,5-hexadiene), respectively. Chloride abstraction led to the isolation of the cationic complexes BBPX[Rh(HD)BF(4)](2) (8), TBPBX[Rh(HD)BF(4)](3) (10), and (S)-BBPBINAP[Rh(HD)BF(4)](2) (12). When BBPX (3), TBPBX (4), and (S)-BBPBINAP (7) were added to 2, 3, and 2 equiv of [Rh(NBD)(2)]BF(4) or [Rh(NBD)(CH(3)CN)(2)]BF(4) (NBD = norbornadiene), respectively, clean formation of BBPX[Rh(NBD)BF(4)](2) (9), TBPBX[Rh(NBD)BF(4)](3) (11), and (S)-BBPBINAP[Rh(NBD)BF(4)](2) (13) was observed. The neutral iridium complex (S)-BBPBINAP[IrCl(COD)](2) (14) was obtained by reaction of (S)-BBPBINAP (7) with 1 equiv of [Ir(2)Cl(2)(COD)(2)] (COD = cyclooctadiene). The complexes were fully characterized including X-ray structural studies of 8, 9, and 13, and preliminary studies on their catalytic activity were performed.     

Study of the conformationally flexible, wide bite-angle diphosphine 4,6-bis(3-diisopropylphosphinophenyl)dibenzofuran in rhodium(I) and palladium(II) coordination complexes

The diphosphine 4,6-bis(3-diisopropylphosphinophenyl)dibenzofuran (abbreviated as (iPr)DPDBFphos) was prepared and studied for its potential as a trans-chelating ligand in transition-metal coordination complexes. In the rhodium norbornadiene complex [((iPr)DPDBFphos)Rh(NBD)]BF(4), which has been characterized with multinuclear NMR spectroscopy, X-ray crystallography, and electrochemical studies, the ligand binds in cis fashion. In the bis(acetonitrile) complexes of rhodium and palladium [((iPr)DPDBFphos)M(CH(3)CN)(2)](BF(4))(n) (M = Rh, Pd; n = 1, 2), the ligand adopts a trans coordination geometry. Density functional theory (DFT, M06-L) calculations predict that the trans conformer is energetically more favorable than the cis by 3.5 kcal/mol. Cyclic voltammograms of the bis(acetonitrile) Pd(II) and Rh(I) complexes contain reversible and quasi-reversible reduction events, respectively, which are preliminarily assigned as metal-based redox reactions.     

Stitching phospholanes together piece by piece: new modular di- and tridentate stereodirecting ligands

The modular one-pot synthesis of a large family of bi- and tridentate 2,5-dimethyl- and 2,5-diphenyl-substituted phospholanes employs air-stable chiral phospholanium chloride salts and primary amines or NH(4)Cl as starting materials. These were transformed into the C(2)-symmetric dimethyl- and diphenylphospholane ligands, which reacted with [Rh(cod)(2)]BF(4) (cod=1,5-cyclooctadiene) to yield the rhodium complexes [Rh(L)(cod)]BF(4) (L=bisphospholane ligands). The corresponding trisphospholane complexes, 11 and 12, were obtained in high yields (81 and 92%, respectively), and fully characterised by NMR spectroscopy, mass spectrometry and elemental analysis. Whilst in the C(3)-symmetric complex 11, containing the tridentate 2,5-dimethylphospholane, the ligand is bound symmetrically, different coordination behaviour was found for the diphenyl-substituted complex 12, in which the coordination of only two of the three phospholane moieties to the metal centre was observed. A DFT study at the B3PW91 level established minimum energy structures consistent with experimental findings in solution and in the solid state. The non-coordinated phospholane unit present in 12 allowed further modification of the complex through the coordination of Au(I)-X (X=Cl, C(6)F(5) and tris(trifluoromethyl)phenyl ((F)Mes)) fragments to the pendant phosphane. To investigate the potential of the new ligands, the enantioselective hydrogenation of a series of prochiral olefins as benchmark substrates, using isolated Rh complexes as catalysts, was studied. The substrates included methyl esters of three dehydro-α-acetamido acids and two itaconic acid derivatives. In general good to excellent enantioselectivities (of up to >99% ee) were observed. Ligand backbone modification by coordination of bulky Au-X substituents to the free phospholane unit in complex 12 led to an outstanding enhancement of the catalyst performance and there was a clear correlation between the properties of the complex periphery and the enantioselectivity.     

Rhodium-catalyzed intramolecular, anti-Markovnikov hydroamination. Synthesis of 3-arylpiperidines

The intramolecular anti-Markovnikov hydroamination of 1-(3-aminopropyl)vinylarenes in the presence of a readily available rhodium catalyst to form 3-arylpiperidines is reported. In contrast to intermolecular hydroamination of vinylarenes, which occurred in high yields in the presence of rhodium catalysts containing DPEphos, the intramolecular reaction occurred in high yield in the presence of [Rh(COD)(DPPB)]BF4 as catalyst. Reactants with substituents beta to the nitrogen occurred in high yield, and these reactions formed 3,5-disubstituted piperidines with high diastereomeric excess. The regiochemistry of these cyclizations contrasts with the regiochemistry of intramolecular hydroaminations catalyzed by lanthanide complexes, group III metal complexes, and platinum complexes, all of which have been reported to form cyclization products from Markovnikov addition.     

On the origin of regio- and stereoselectivity in the rhodium-catalyzed vinylarenes hydroboration reaction

We studied the hydroboration of vinylarenes using rhodium complexes bearing atropoisomeric ligands. For the first time, an NMR spectroscopy study of the styrene and catecholborane addition to the precursor of catalyst [Rh(COD)(L-L)]BF(4), where L-L = (R)-BINAP and (R)-QUINAP, showed evidence of the structure of intermediates involved in the catalytic cycle. On the basis of this evidence, and using DFT calculations and QM/MM strategies, we investigated the origin of regio- and stereoselectivity. We determined the structure and stability of the key intermediates for several ligands and substrates and found excellent agreement between the relative stability of the intermediates and the experimentally observed trends. Using model systems, we analyzed the role of the steric and electronic features of the ligands and the substrates in detail.     

How to turn the catalytic asymmetric hydroboration reaction of vinylarenes into a recyclable process

Optically pure rhodium(I) complexes [Rh(cod)(Lbond;L)]X (cod=cyclooctadiene; L-L= (R)-2,2'-bis(diphenylphosphino)1-1'-binaphthyl ((R)-BINAP), (S,S)-2,4-bis(diphenylphosphino)pentane ((S,S)-BDPP), 2-diphenylphosphino-1-(1'-isoquinolyl)naphthalene ((S)-QUINAP); X=BF(4), PF(6), SO(3)CF(3), BPh(4)) were immobilised onto smectite clays such as montmorillonite K-10 (MK-10) and bentonite (Na(+)-M). (19)F, (31)P and (11)B NMR experiments recorded in CDCl(3) during the impregnation process provided evidence that montmorillonite K-10 may immobilise ionic metal complexes throughout the cationic and anionic counterparts. However, when bentonite was used as the solid, only the cationic metal complex was immobilised through cationic exchange while the counteranion remained in solution. When we used these preformed catalytic systems in the hydroboration of prochiral vinylarenes, we obtained high activities and enantiomeric excess with (S)-1-(2-diphenylphosphino-1-naphthyl)isoquinoline-modified rhodium complexes. These activities and selectivities are competitive with the homogeneous counterparts. The significant features of this method are the simple separation and good retention of the active metal in the solid, which allows efficient recycling even on exposure to air.     

Comparison of structure and reactivity of phosphine-amido and hemilabile phosphine-amine chelates of rhodium

A series of mono- and binuclear rhodium(I) complexes bearing ortho-phosphinoanilido and ortho-phosphinoaniline ligands has been synthesized. Reactions of the protic monophosphinoanilines, Ph(2)PAr or PhPAr(2) (Ar = o-C(6)H(4)NHMe), with 0.5 equiv of [Rh(μ-OMe)(COD)](2) result in the formation of the neutral amido complexes, [Rh(COD)(P,N-Ph(2)PAr(-))] or [Rh(COD)(P,N-PhP(Ar(-))Ar)] (Ar(-) = o-C(6)H(4)NMe(-)), respectively, through stoichiometrically controlled deprotonation of an amine by the internal methoxide ion. Similarly, the binuclear complex, [Rh(2)(COD)(2)(μ-P,N,P',N'-mapm(2-))] (mapm(2-) = Ar(Ar(-))PCH(2)P(Ar(-))Ar), can be prepared by reaction of the protic diphosphinoaniline, mapm (Ar(2)PCH(2)PAr(2)), with 1 equiv of [Rh(μ-OMe)(COD)](2). An analogous series of hemilabile phosphine-amine compounds can be generated by reactions of monophosphinoanilines, Ph(2)PAr' or PhPAr'(2) (Ar' = o-C(6)H(4)NMe(2)), with 1 equiv of [Rh(NBD)(2)][BF(4)] to generate [Rh(NBD)(P,N-Ph(2)PAr')][BF(4)] or [Rh(NBD)(P,N-PhPAr'(2))][BF(4)], respectively, or by reactions of diphosphinoanilines, mapm or dmapm (Ar'(2)PCH(2)PAr'(2)), with 2 equiv of the rhodium precursor to generate [Rh(2)(NBD)(2)(μ-P,N,P',N'-mapm)][BF(4)](2) or [Rh(2)(NBD)(2)(μ-P,N,P',N'-dmapm)][BF(4)](2), respectively. Displacement of the diolefin from [Rh(COD)(P,N-Ph(2)PAr(-))] by 1,2-bis(diphenylphosphino)ethane (dppe) yields [Rh(P,P'-dppe)(P,N-Ph(2)PAr(-))] which, while unreactive to H(2), reacts readily and irreversibly with oxygen to form the peroxo complex, [RhO(2)(P,P'-dppe)(P,N-Ph(2)PAr(-))], and with iodomethane to yield [RhI(CH(3))(P,P'-dppe)(P,N-Ph(2)PAr(-))]. Hemilabile phosphine-amine compounds can also be prepared by reactions of [Rh(P,P'-dppe)(P,N-Ph(2)PAr(-))] with Me(3)OBF(4) or HBF(4)·Et(2)O, resulting in (thermodynamic) additions at nitrogen to form [Rh(P,P'-dppe)(P,N-Ph(2)PAr')][BF(4)] or [Rh(P,P'-dppe)(P,N-Ph(2)PAr)][BF(4)], respectively. The nonlabile phosphine-amido and hemilabile phosphine-amine complexes were tested as catalysts for the silylation of styrene. The amido species do not require the use of solvents in reaction media, can be easily removed from product mixtures by protonation, and appear to be more active than their hemilabile, cationic congeners. Reactions catalyzed by either amido or amine complexes favor dehydrogenative silylation in the presence of excess olefin, showing modest selectivities for a single vinylsilane product. The binuclear complexes, which were prepared in an effort to explore possible catalytic enhancements of reactivity due to metal-metal cooperativity, are in fact somewhat less active than mononuclear species, discounting this possibility.     

Early-late heterobimetallic alkoxides as model systems for late-transition-metal catalysts supported on titania

Titanium complexes with chelating alkoxide ligands [TiCp*(O(2)Bz)(OBzOH)] (1) and [TiCp*(Me)((OCH(2))(2)Py)] (2) were synthesised by reaction of [TiCp*Me(3)] (Cp*=eta(5)-C(5)Me(5)) with 2-hydroxybenzyl alcohol ((HO)(2)Bz) and 2,6-pyridinedimethanol ((HOCH(2))(2)Py), respectively. Complex 1 reacts with [(M(mu-OH)(cod))(2)] (M=Rh, Ir) to yield the early-late heterobimetallic complexes [TiCp*(O(2)Bz)(2)M(cod)] [M=Rh (3), Ir (4)]. Carbon monoxide readily replaces the COD ligand in 3 to give the rhodium dicarbonyl derivative [TiCp*(O(2)Bz)(2)Rh(CO)(2)] (5). Compound 2 reacts with [(M(mu-OH)(cod))(2)] (M=Rh, Ir) with protonolysis of a Tibond;Me bond to give [TiCp*((OCH(2))(2)Py)(mu-O)M(cod)] [M=Rh (6), Ir (7)]. The molecular structures of complexes 3, 5 and 7 were established by single-crystal X-ray diffraction studies.     

Bidentates versus monodentates in asymmetric hydrogenation catalysis: synergic effects on rate and allosteric effects on enantioselectivity

C 1-Symmetric phosphino/phosphonite ligands are prepared by the reactions of Ph 2P(CH 2) 2P(NMe 2) 2 with ( S)-1,1'-bi-2-naphthol (to give L A ) or ( S)-10,10'-bi-9-phenanthrol (to give L B ). Racemic 10,10'-bi-9-phenanthrol is synthesized in three steps from phenanthrene in 44% overall yield. The complexes [PdCl 2( L A,B )] ( 1a, b), [PtCl 2( L A,B )] ( 2a, b), [Rh(cod)( L A,B )]BF 4 ( 3a, b) and [Rh( L A,B ) 2]BF 4 ( 4a, b) are reported and the crystal structure of 1a has been determined. A (31)P NMR study shows that M, a 1:1 mixture of the monodentates, PMePh 2 and methyl monophosphonite L 1a (based on ( S)-1,1 '-bi-2-naphthol), reacts with 1 equiv of [Rh(cod) 2]BF 4 to give the heteroligand complex [Rh(cod)(PMePh 2)( L 1a )]BF 4 ( 5) and homoligand complexes [Rh(cod)(PMePh 2) 2]BF 4 ( 6) and [Rh(cod)( L 1a ) 2]BF 4 ( 7) in the ratio 2:1:1. The same mixture of 5- 7 is obtained upon mixing the isolated homoligand complexes 6 and 7 although the equilibrium is only established rapidly in the presence of an excess of PMePh 2. The predominant species 5 is a monodentate ligand complex analogue of the chelate 3a. When the mixture of 5- 7 is exposed to 5 atm H 2 for 1 h (the conditions used for catalyst preactivation in the asymmetric hydrogenation studies), the products are identified as the solvento species [Rh(PMePh 2)( L 1a )(S) 2]BF 4 ( 5'), [Rh(S) 2(PMePh 2) 2]BF 4 ( 6') and [Rh(S) 2( L 1a ) 2]BF 4 ( 7') and are formed in the same 2:1:1 ratio. The reaction of M with 0.5 equiv of [Rh(cod) 2]BF 4 gives exclusively the heteroligand complex cis-[Rh(PMePh 2) 2( L 1a ) 2]BF 4 ( 8), an analogue of 4a. The asymmetric hydrogenation of dehydroamino acid derivatives catalyzed by 3a, b is reported, and the enantioselectivities are compared with those obtained with (a) chelate catalysts derived from analogous diphosphonite ligands L 2a and L 2b , (b) catalysts based on methyl monophosphonites L 1a and L 1b , and (c) catalysts derived from mixture M. For the cinnamate and acrylate substrates studied, the catalysts derived from the phosphino/phosphonite bidentates L A,B generally give superior enantioselectivities to the analogous diphosphonites L 2a and L 2b ; these results are rationalized in terms of delta/lambda-chelate conformations and allosteric effects of the substrates. The rate of hydrogenation of acrylate substrate A with heterochelate 3a is significantly faster than with the homochelate analogues [Rh( L 2a )(cod)]BF 4 and [Rh(dppe)(cod)]BF 4. A synergic effect on the rate is also observed with the monodentate analogues: the rate of hydrogenation with the mixture containing predominantly heteroligand complex 5 is faster than with the monophosphine complex 6 or monophosphonite complex 7. Thus the hydrogenation catalysis carried out with M and [Rh(cod) 2]BF 4 is controlled by the dominant and most efficient heteroligand complex 5. In this study, the heterodiphos chelate 3a is shown to be more efficient and gives the opposite sense of optical induction to the heteromonophos analogue 5.     

Hydrosilylation reactions catalyzed by rhodium complexes with phosphine ligands functionalized with imidazolium salts

Hydrosilylation reactions of styrene with triethoxysilane catalyzed by rhodium complexes with phosphine ligands functionalized with imidazolium salts are reported. In comparison with Wilkinson’s catalyst, Rh(PPh₃)₃Cl, all of the present rhodium complexes with phosphines functionalized with imidazolium salts exhibit higher catalytic activity and selectivity.     

Synthesis and reactions of binuclear diolefin rhodium(I) compounds bridged by nitrogen heterocycles. Crystal structure of dichloro-di-1,5-cyclooctadiene(μ-pyrazine)-dirhodium(I) [{Rh(1,5-C8H12)Cl}2(μ-C4H4N2)]

Binuclear complexes of rhodium(I) of the type [(dien)(X)Rh(μ-N-N)Rh(X)(dien)] (dien = 1,5-cyclooctadiene or norbornadiene; N-N = pyrazine, 4,4′-bipyridine or Phenazine and X = Cl or Br) with bridging heterocycles have been isolated and their reactions with carbon monoxide, 2,2′-bipyridine and 1,10-phenanthroline investigated. The crystal structure of [(COD)(Cl)Rh(μ-pyrazine)Rh(Cl)(COD)] has been determined.     

Synthesis and Structures of RhI and IrI Complexes Supported by N‐Heterocyclic Carbene‐Phosphinidene Adducts

N‐Heterocyclic carbene‐phosphinidene adducts of the type (IDipp)PR [R = Ph ( 5 ), SiMe₃ ( 6 ); IDipp = 1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene] were used as ligands for the preparation of rhodium(I) and iridium(I) complexes. Treatment of (IDipp)PPh ( 5 ) with the dimeric complexes [M(μ‐Cl)(COD)]₂ (M = Rh, Ir; COD = 1,5‐cyclcooctadiene) afforded the corresponding metal(I) complexes [M(COD)Cl{(IDipp)PPh}] [M = Rh ( 7 ) or Ir ( 8 )] in moderate to good yields. The reaction of (IDipp)PSiMe₃ ( 6 ) with [Ir(μ‐Cl)(COD)]₂ did not yield trimethylsilyl chloride elimination product, but furnished the 1:1 complex, [Ir(COD)Cl{(IDipp)PSiMe₃}] ( 9 ). Additionally, the rhodium‐COD complex 7 was converted into the corresponding rhodium‐carbonyl complex [Rh(CO)₂Cl{(IDipp)PPh}] ( 10 ) by reaction with an excess of carbon monoxide gas. All complexes were fully characterized by NMR spectroscopy, microanalyses, and single‐crystal X‐ray diffraction studies.     

Site-selective and stepwise complexation of two M(cod)+ (M = Rh,Ir) fragments with calix[4]arene

The reaction of [(cod)M(mu-OMe)]2 (M = Rh, Ir; cod = cycloocta-1,5-diene) with calix[4]arenes (LH4) in the molar ratio of 0.5-0.6:1 gave the rhodium and iridium pi-arene complexes [(cod)M(eta 6-LH3)], while that in the molar ratio of 1.1-1.5:1 (M = Rh) led to the selective formation of the dinuclear complexes [((cod)Rh)2(eta 6:eta 2-LH2)] in which one of the Rh(cod)+ fragments is coordinated by an eta 6-aryl group and the other by two phenolic oxygen atoms; the stepwise synthesis of the Rh-Ir heterobimetallic analogue of the latter complex was further achieved.     

Oxidation-promoted synthesis of ferrocenyl planar chiral rhodium(iii) complexes for C–H functionalization catalysis

The chemical oxidation of rhodium(i) complexes [Rh(L)(COD)][BF4], where L is a ferrocenyl phosphine/N-heterocyclic carbene ligand, with 2 equiv. of a triaryl-aminium salt [(4-BrC6H4)3N][BF4] in acetonitrile gave planar chiral, air-stable [Rh(L–H)(MeCN)3][BF4]2 complexes where the ferrocene (C5H4CH2ImR or C5H4CH2BImCH2Mes) ring has been C–H activated at the position 2 in good to excellent yields. An important reactivity difference between our complexes and the ubiquitous [Cp*Rh(MeCN)3]X2 complex has been observed in the Grignard-type arylation of 4-nitrobenzaldehyde.     

Heterometallic cluster complexes (RhMo, RhW) containing bridging 1,2-dicarba-closo-dodecaborane-1,2-dichalocogenolato ligands

The 16-electron half-sandwich rhodium complex [Cp*Rh{E2C2(B10H10)}] [Cp* = eta5-C5Me5, E = S (1a), Se (1b)] [Cp*Rh{E2C2(B10H10)} = eta5-pentamethylcyclopentadienyl[1,2-dicarba-closo-dodecaborane(12)-dichalcogenolato]rhodium] reacted with Mo(CO)3(py)3 in the presence of BF3.Et2O in THF solution to afford the {Cp*Rh[E2C2(B10H10)]}2Mo(CO)2 (E = S (3a); Se (3b)), {Cp*Rh[S2C2(B10H10)]}{Mo(CO)2[S2C2(B10H10)]} (4). The voluminous di-tert-butyl substituted Cp half-sandwich rhodium complex [Cp'Rh{E2C2(B10H10)}] [E = S (2a), Se (2b)] [CpRh{E2C2(B10H10)} = eta5-(1,3-di(tert-butyl)cyclopentadienyl-[1,2-dicarba-closo-dodecaborane(12)-dichalcogenolato]rhodium) reacted with W(CO)3(py)3 in the presence of BF3.Et2O in THF solution to give the {Cp'Rh[S2C2(B10H10)]}{W(CO)2[S2C2(B10H10)]} (5) and {Cp'Rh[Se2C2(B10H10)]}(mu-CO)[W(CO)3] (6), respectively. The complexes have been fully characterized by IR and NMR spectroscopy as well as by elemental analyses. The X-ray crystal structures of the complexes 3-6 are reported.     

Neutral and cationic complexes with P-bonded 2-pyridylphosphines as N-donor ligands toward rhodium. Electrical charge vs steric hindrance on the conformational control

Bimetallic palladium(II)-rhodium(I) and gold(I)-rhodium(I) complexes of the type [(4,4'-Me2-bipy)(C6F5)Pd(mu-PPh(3-n)Pyn)Rh(diene)](BF4)2 and [(C6F5)Au(mu-PPh(3-n)Pyn)Rh(diene)](BF4) (n = 2, 3; Py = 2-pyridyl) have been synthesized. The P donor atom of the bridging ligands (mu-PPh(3-n)Pyn) is coordinated to the Pd or to the Au center. The resulting complexes react with [Rh(diolefin)(solv)2]+ (solv = acetone) in a way similar to pyrazolylborates, affording square-planar or pentacoordinated rhodium complexes with two or the three N-donor ends chelating the Rh atom. The metallacycles formed upon chelation can adopt one of two conformations in the square-planar Rh(I) complexes, either bringing the other metal close to the Rh center or bringing it to a remote position. The first conformation is preferred for the gold P-coordinated complexes and the second for the palladium complexes. The X-ray structures of [(4,4'-Me2-bipy)](C6F5)Pd(mu-PPhPy2)Rh(COD)](BF4)2 (COD = 1,5 cyclooctadiene) and [Au(C6F5)(mu-PPhPy2)Rh(TFB)](BF4) (TFB = 5,6,7,8-tetrafuoro-1,4-dihydro-1,4-etenonaphthalene) are reported.     

Solvent-free synthesis of bisferrocenylimines and their rhodium(I) complexes

The solvent-free reaction of ferrocenecarboxaldehyde and diaminoalkanes under solvent-free conditions gave bisferrocenylimines (L) in excellent yields. Cationic rhodium(I) complexes with the formulation [Rh(COD)(L)]ClO₄ were prepared by the reaction of [Rh(COD)Cl]₂ with the bisferrocenylimines in the presence of silver perchlorate. The compounds were characterised by NMR, IR, MS and elemental analysis. The X-ray crystal structures of two rhodium(I) complexes are also reported.