Binuclear complex

1 Binuclear Complexes.- Heterobimetallic complexes reported in 1993 contain interactions between the following pairs of metal atoms TiCo , ZrRh, NbRe , TaRh,  

FeMo83.89.391 peRu , FePd -, FeAg, FeW. peRe 383.390 P pj384.388.393-5 FeAu388, CoMo -391,396-7 CoMo 39. 396-7, CoRu398, CoRh399, CoW3 6-.  

In two publications, Moro-oko and coworkers describe the synthesis of organyl-bridged iton-manganese complexes from the non metal-metal bonded vinylidene compound [Cp Mn(CO)2 =C=CHFe(CO)2Cp ] (Cp =C5H4Me). Thus protonation affords [Cp (CO)2Mn(p-C=CH2)Fe(CO)2Cp] while addition of Bu Li followed by quenching with methanol yields 

Heterometallic clusters reported in 1994 include those containing the following metals CrCo °, CrRh, CrW CrRe - , MnFe , MnCo , MnCu MnMo, MnRu MnRh,  

Compounds with Bonds Between Transition and Main Croup Metals 

1 Binuclear Canplexes. - Hetero-binuclear derivatives studied in 1985, which are neither listed in Table 1 nor are simple ligzuid modified derivatives of these listed complexes, contain bonding interactions between the following pairs of metals Ti and W or Fe Zr and Pe jq, Cr 

An unbridged metal-metal bond linking early-late transition metals is present in the novel actinide complex [ThRuI(C0)2CpCp2] and in [TlRu(CO)2(NMe3)3Cp]. Stereochemically non-rigid complexes 

Full details of the structure and cls-trans isomerisation of [FeRu(M-CO)2(CO)2Cp2] are published its transformation into complexes bridged by various organic ligands is also described. Paramagnetic 

Ligand induced cleavage of one Zr-Ru bond of [Cp2Zr Ru(CO)2Cp)2] affords a binuclear species and [RuK(C0)2Cp] thus CO reversibly produces [Cp2(OC)Zr(u-o,n -C5H4)Ru(CO)2] which undergoes facile CO substitution by The structure and properties of ferrocene analogues 

Two phosphido bridges link early metals, Th, Ti or zr to later transition metals in species which may have some direct metal-metal interaction. The W-Re bond in [HRe(M-PPh2)(CO)9] is displaced on addition of ligands to Re and if PPh2H is added, subsequent thermolysis affords dlbridged species (HRe((i-PPh2)2H(CO)7] which can be transformed via 

The MLCT absorption bands of the two chromophores strongly overlap. 

It must be pointed out that the relative energy ordering of the MLCT states of the two chromophores, previously inferred from indirect evidence, has now been unequivocally established by the use of time-resolved resonance Raman (TR ) techniques [76]. To this purpose, the following binuclear complex has been synthesized  

Because of the well-known close electronic similarity between bpy and phen, this phen-bpy complex is expected to have practically the same MLCT excited-state energy levels as the previously studied all-bpy species. On the other hand, bpy- and phen-based MLCT excited states are expected to be distinguishable on the basis of their vibrational spectra. By comparing the TR spectra (50 ns after excitation) of this complex with those of similar all-bpy and all-phen complexes, clear evidence is obtained for the presence of 

In this complex, in spite of the binding mode of the bridging cyanide, the Re-based MLCT states are at considerably higher energies than the Ru-based ones, so that distinct MLCT bands are present in the absorption spectrum, selective (or predominant) excitation of the Ru-based and Re-based chromophores is possible, and a substantial driving force for energy transfer is present. As a matter of fact, as shown by emission-excitation studies, and by TR experiments, very efficient energy transfer takes place in this system from the Re-based to the Ru-based MLCT state [94]. 

The spectrum of the Re(I)-Ru(II) complex, on the other hand, has much smaller shifts of excited-state CO bands relative to the ground-state ones, consistent with the fact that energy transfer has already removed excitation from the Re-based chromophore, producing the Ru-based MLCT state 

6) form dimeric molecules with trigonal planar coordination of the metal atoms L-M(-OR)2M-L. The same structure is observed for [Mg(OC6H3Bu 2- 

Dimers containing two pentacoordinated atoms are the molecules of the [M(OR)nL4.n]2 type — [LiOPh]2(18-crown-6) [1184] (n= 1), 

Much less common are dimers, where the metal coordination polyhedra share a common face. As examples can be taken [(Bu SiO)Ba([i-OSiBu 3)3Ba(THF)] built up of 2 tetrahedra [497] or bimetallic t-butoxides 

In the asymmetric [THF(Ph3CO)Ba(p-OCPh3)3Ba(THF)2] molecule the connected elements are trigonal bipyramids [497], while in that of [U2(p-OBu )3(OBu )6] they are the octahedra around U(IV) andU(V) atoms [419], In the [ReYI202( J.-0)((j.-0Me)2(0Me)4]dimerthe metal atoms are connected by a Re-Re bond (2.56 A) in addition to 3 alkoxobridges [519]. 

In the molecule of the [K(OC6H2(CF3)3-2,4,6)(THF)3]2 complex the 2 distorted octahedra share 4 vertexes — 2 OAr and 2 THF ones (along with the extra connection via K...F interaction) [246]. 

Publications concerning larger mercury containing clusters include reports on the quantitative synthesis of [Ruj(CO)is n -C)C(O)CF3 (pj-C)(Hj-HgCF0] . the preparation and dynamic behaviour of [Os,o(CX)) (M,-C)(ii-HgX)] (X=Cl,BrJ,CF CpMo(CO)3) and [ OsJCOUm-C) i( j.-Hg)], and the reduction of trimercury clusters [OS, Hg3(CO)4 ( X-C)2], resulting in extrusion of a mercury atom to afford [Os,tHgz(p.-C)2(CO)42], which itself can be oxidised in a step-wise fashion to the tri- and dianion .  

Reports on simple transition metal compounds of tin include the preparation of [Cp Ni(CD)(SnPh3)] , iron-tin porphyrin complexes , mixed tin-silicon compounds [Fe(CD)3 

AJLKudinov. D.V.MiinUov and MXRybin ya. Organomet.Chem.USSR., 1992. 5. 103. 

Khalifa, J-Y.SailIaid.F.Gloagiien,CXeFloc h,F.YP6tillonand J.Talarmin.A/eN /.CAein., 1992,16, 847. 

Two papers document the synthesis of heterobimetallic compounds of titanium and cobalt Reaction of [MeH(OBu ),] with (HCo(CO)J affords I(Bu 0),Ti-Co(CO)4] which contains an unsupported metal-metal bond , while addition of [Coi(CO)J to [Cp 2Ti(C2Hi)J (Cp aCjUtSiMe,) gives the radical [Cp jTi0i-CjPh)2Co(CO)l in which a weak metal-metal 

Compounds with Bonds Between Transitiwi and Main Group Metals 

OBu In] with metal hexacarbonyls gives the unusual cmnplexes [(CO)jMSn(p.-OBu ),InM(CO)3] (M=Mo,Cr) via initial coordination of the metal at the indium and tin sites . Two papers include both indium and thallium compounds. Thus, the preparation of [ CpM(CX )3 3E] (MssMo,Cr,Es In,Tl) is described, extended Hiickel calculations indicating that the In-Mo bond is polar, and tire ic-bonding interaction is only weak . The synthesis and electrochemistry of the porphyrin (P) complexes [(P)ERe((X))s] is also described . Hnally one report describes the synthesis of phosphine substituted crown complexes containing a thallium-iridium bond. The nature of this interaction has been studied in some detail . 

Gdrling, N.R0sch, D.E.Ellis and H.Schmidtnur, Inorg.Chem.. 1991,, 3986. 

Banisier, LB.Goirell, W.CIegg and K.AJprgensen, J.Chem.Soc.. Dalton Trans.. 1991,1105. 

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Creutz C and Taube H 1973 Binuclear complexes of ruthenium amines J. Am. Chem. Soc. 95 1086... 

This binuclear complex is also fluxional and has the structure shown in Fig. 7.4a. A1(BH4)3 reacts readily with NMe3 to give a 1 1 adduct in which Al adopts the unusual pentagonal... 

Numerous tetrahedral halogeno complexes [T1" X4] (X = Cl, Br, I) have been prepared by reaction of quaternary ammonium or arsonium halides on TIX3 in nonaqueous solution, and octahedral complexes TI "X< ] (X = Cl, Br) are also well established. The binuclear complex Cs3[Tl2"Cl<)J is an important structural type which features two TlCls octahedra sharing a common face of 3 bridging Cl atoms (Fig. 7.9) the same binuclear complex structure is retained when Tl " is replaced by Ti ", V ", Cr " and Fe " and also in K3W2CIS and CssBiily, etc. 

The binuclear complex [Mo2Cl2N2o] features a terminal nitrido ligand, N=, as well as terminal and bridging azido ligands, i.e. [ (MoCl(N)(t, -N,)2(/t,t -Nt)l2] Concatenations larger than N3 are rare. The planar bridging N4... 

Figure 13.19 Proposed structures for (a) the tridentate cycZo-polyarsane complex [Cr(CO)3(As5Mes)], and (b) the bismonodentate binuclear complex [ Cr(CO)sl2(As5Me5)].

Bimetallic catalysis by binuclear complexes of Cu, Fe, Mn, Ni, Pd, and Rh with heterocyclic ligands 98T12985. 

Macroheterocycles capable of forming binuclear complexes with a common ligand 96CC457. 

In the foregoing it has been assumed that the complex species does not contain more than one metal ion, but under appropriate conditions a binuclear complex, i.e. one containing two metal ions, or even a polynuclear complex, containing more than two metal ions may be formed. Thus interaction between Zn2+ and Cl ions may result in the formation of binuclear complexes, e.g. [Zn2Cl6]2-, in addition to simple species such as ZnCl3 and ZnCl -. The formation of bi- and poly-nuclear complexes will clearly be favoured by a high concentration of the metal ion if the latter is present as a trace constituent of a solution, polynuclear complexes are unlikely to be formed. 

Using less than 3 mol of phosphine affords binuclear complexes Rh2Cl6(PR3) (n = 3,4), also obtained by reproportionation (Figure 2.57). 

Intramolecular Au-Au interactions are found in some binuclear complexes (AuX)2, where X is a chelating ligand like dithiocarbamate, phosphine ylid (R2P(CH2)2) or bidentate phosphines. Therefore, in [Au(S2CNBu2)]2 the Au-Au distance is 2.78 A (Figure 4.50). 

Transition metal atoms in the synthesis of binuclear complexes. E. P. Kiindig, M. Moskvits and... 

Due to the high a-C,H acidity in the alkoxyethylidene complexes 6 (e.g.,piCa=8 (R=Me)) [ 16], transformations via an enolate analog are possible and have been used to introduce additional functionality into the carbene side chain to access various Fischer carbene complexes [3]. The a,/J-unsaturated complex 8 could be obtained from 6 (R=Et) by an aldol-type condensation with benzaldehyde 7 in the presence of triethylamine and trimethylsilyl chloride (Scheme 2) [17]. This reaction proceeds completely diastereoselectively to yield only the trans-isomer. Analogously, binuclear complexes have been prepared from 6 and 1,3-and 1,4-phthaldialdehyde in good yields [17]. This type of condensation has... 

A crystal-structure determination on [Ni(PhCH2CS2)2] showed evidence of a Ni-Ni bond (Ni—Ni distance, 256 pm) in a bridging, acetate-cage, binuclear complex (363). Each nickel atom is 5-coordinate and is in a tetragonally distorted, square-pyramid spectroscopic evidence for a Ni-Ni bond has been obtained (364). The polarized crystal spectra showed more bands than predicted for a mononuclear, diamagnetic, square-planar nickel(Il), and the spectra are indicative of substantial overlap of the d-orbitals between the two nickel atoms. The bis(dithiobenzation)nickeKII) complex was found to exhibit unusual spectrochemical behavior (365). 

A versatile route to 3-benzoheteropines has been reported starting from o-phthalaldehyde, including the first preparations of 3-benzarsepines and the parent 3-benzothiepin and 3-benzoselenepins <96CC2183>. l,7-Dihydro-l//-dibenzo[c,c]tellurepin has been prepared from 2,2 -bis(bromomethyl)biphenyl and potassium tellurocyanate and its complexes with palladium and ruthenium species have been studied, a number of mono- and binuclear complexes are formed <96RTC427>. 

An obvious limitation to the hydrogen-elimination method, especially for early transition metal elements, is the availability of transition metal hydrides (this applies also to the HCl elimination) or binuclear complexes. 

J) -CHj, 318 (74) NH3, 345 (II) HjO, 380 ( 75). This shows that both organo-ligands exert a very strong ligand field comparable with that of CN and establishes their position in the spectrochemical series. It is a pity that the second d-d transitions ( T2g-(- A,g), which would establish the position of these ligands in the nephelauxetic series, have not yet been reported. Two bands have, however, been reported for the binuclear complex [(NC)5Co(CFjCFj)Co(CN)5] - at 320 and 276 nm (I2I). 

The above proposed process can be expected to easily put into practice as ammonia is abuandant as the main feedstock for fertilizer. Nevertheless, there is also a problem that Co(NH3)6 is apt to be oxidized to Co(NH3)6 which is unable to form the peroxo binuclear complex and ineffective to O2 solubility enhancement, thus reaction (4) is inhibited. But Co will be relatively stable, and Co may be reduced to Co " by H2O [12]. As a result, a regenration method has also been proposed by using the activated carbon as the catalyst[7], in which Co(NH3)6 dissociation into Co " and NH3 occurs on the activated carbon surface followed by reduction of Co with H2O into Co, O2 and H. ... 

It is of incidental interest that a little work has been done on dicobalt systems. Doyle and Sykes have made a study of the reduction of decammine-//-amidodi-cobalt(Ill), (NH3)5Co NH2-Co(NH3)5 , by V(II). Since the rate is independent of hydrogen-ion concentration the mechanism cannot involve an amide bridge and must be outer-sphere, as it is in the case of the reduction of Co(NH3)6 by V(1I) . Both the binuclear complex and Co(NH3)6 are inert to substitution but the former is capable of functioning as a two-equivalent oxidant. Thus the two likely mechanisms are... 

Gold palladium binuclear complexes [141] can be synthesized by reaction of [Au (C6F5)(tht)] with the palladium derivative trans-[pdRR (dppm)2] where R = R = QF5 R = R = CgCls R = C Fs, R = Cl. It was however not possible to distinguish the two structures for these complexes shown in Figure 3.20 ... 

The absorption bands of the binuclear complexes are red-shifted compared to the mononuclear analogs, and this is attributed to intramolecular n-n interactions between C N C ligands in solution (Figure 5.21a). 

A special representative of class IIIA is the Creutz-Taube complex [101]. This is a binuclear complex [(NHjlsRufpyrazinelRufNHj) ]. Various experimental results led to conflicting conclusions concerning its electronic structure. A combined attack [101] has shown, however, that we are not dealing with a... 

Strekas TC, Spiro TG. 1975. Resonance Raman spectra of superoxide-bridged binuclear complexes. p,-Superoxo-decacyanodicobaltate(5—) and /n-superoxo-decaamminedicobalt (5 +). Inorg Chem 14 1421. 

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