Isabelle Jourdain

Interplay of Structural Flexibility and Crystal Packing in a Series of Paramagnetic Cyclopentadienyl/Dithiolene Mo and W Complexes: Evidence for Molecular Spin Ladders

The structural flexibility of [Cp2M(dithiolene)] complexes (M=Mo, W; dithiolene=dmit2−, dmid2−, dsit2−; the [CpMo(dmid)] complex is depicted on the right) is manifested in various folding angles of the MS2C2 metallacycle in a series of charge-transfer salts with TCNQF4. The evolution of the electronic structures with the folding angle induces different geometries for the dimeric [{Cp2M(dithiolene)+.}2] entities. The organization of these entities in the solid state reveals one-dimensional intermolecular interactions, as confirmed by the magnetic behavior of these salts, which are characteristic of a spin chain or a rare spin ladder motif (shown on the right).

(Phenylthiomethyl)silanes and (butyltelluromethyl)silanes as novel bifunctional ligands for the construction of dithioether-, ditelluroether- and transition metal /silicon complexes

Abstract The functionalized silanes (PhSCH2)2SiPh2 (1a), (PhSCH2)2Si(vinyl)Me (1b), (PhSCH2)2Si(H)Me (1c) and (PhSCH2)3SiH (1d) have been prepared and co-ordinated as chelating dithioether ligands or via a covalent MSi bond to various transition metal centers. Thus, reaction of 1a with [PtCl2(PhCN)2] affords the dithioether complex cis-[PtCl2{(PhSCH2)2SiPh2}] (3), which exist in solution as mixtures of dl - and meso-invertomers. Treatment of [Re(μ-Br)(CO)3THF]2 with 1a–c yielded the stereochemically rigid chelate complexes fac-[ReBr(CO)3{(PhSCH2)2SiR1R2}] (R1, R2=Ph (4a)), (R1=vinyl, R2=Me (4b)), (R1=H, R2=Me (4c)). Due to the presence of two different substituents R1 and R2 on Si, 4b and 4c are isolated as 50:50 mixtures of diastereomers. The presence of a SiH function in 1c,d can be exploited for SiH activation reactions. Thus, oxidative addition on [Pt(PPh3)2(CH2CH2)] yields the fluxional hydrido silyl complex [Pt(H)(PPh3)2{Si(CH2SPh)2Me}] (5a) and the rigid derivative [Pt(H)(PPh3)2{Si(CH2SPh)3}] (5b). The ditelluroether complexes cis-[PtCl2{(RTeCH2)2SiMe2)] (6a, R=Ph), (6b, R=n-Bu) are obtained by treatment of [PtCl2(PhCN)2] with (PhTeCH2)2SiMe2 (2a) and (n-BuTeCH2)2SiMe2 (2b), respectively. The complex fac-[ReBr(CO)3{(n-BuTeCH2)2SiMe2}] (7) results from the reaction of [Re(μ-Br)(CO)3THF]2 with (2b). The new compounds have been studied by multinuclear NMR techniques, the crystal structures of 3, 4a, 5 and 6b have been determined by X-ray diffraction studies.

Synthesis and reactivity of dinuclear iron–platinum, chromium–platinum, molybdenum–platinum and tungsten–platinum complexes with bridging carbonyl, isocyanide and aminocarbyne ligands. An empirical study on the parameters decisive for the bonding mode of the isocyanide ligand

The dppm-bridged heterobimetallic μ-carbonyl complexes [(OC) 4 M(μ-CO)(μ-dppm)Pt(PPh 3 )] ( 1a , M=Cr; 1b , M=Mo; 1c , M=W) have been prepared by the reaction of [M(CO) 5 (η 1 -dppm)] (M=Cr, Mo, W) with [Pt(CH 2 CH 2 )(PPh 3 ) 2 ]. The outcome of stoichiometric isocyanide addition to 1 is electronically controlled by the π-accepting propensity of CNR. Addition of isocyanide ligands with strongly electron withdrawing substituents R affords the isonitrile-bridged complexes [(OC) 4 M(μ-CN–R)(μ-dppm)Pt(PPh 3 )] 2 (M=W; R=CF 3 ), 3 ( 3a , M=Cr; 3b M=Mo, 3c M=W; R=CH 2 SO 2 p -tolyl), and 4 (M=W; R=[CH 2 PPh 3 ][PF 6 ]. With less π-accepting isocyanides (R=CH 2 Ph, C 6 H 11 , CH 2 PO(OEt) 2 ,) the labile complexes [(RNC)(OC) 3 W(μ-CO)(μ-dppm)Pt(PPh 3 )] ( 5–7 ) ligated by a terminal isonitrile ligand are formed. In contrast, treatment of [(OC) 3 Fe(μ-CO)(μ-dppm)Pt(PPh 3 )] with CNCH 2 PO(OEt) 2 yields exclusively [(OC) 3 Fe{μ-CNCH 2 PO(OEt) 2 }(μ-dppm)Pt(PPh 3 )] ( 9 ) with the isocyanide ligand in a bridging bonding mode. Upon protonation of 2 and 3b with HBF 4 , the stable μ-aminocarbyne complexes [(OC) 4 M(μ-CN(H)R′)(μ-dppm)Pt(PPh 3 )][BF 4 ] ( 10–11 ) are formed by electrophilic addition of H + on the basic isonitrile nitrogen atom. The molecular structures of 1a , c , 2 and 3c have been determined by X-ray diffraction methods. The μ-CO and the μ-CNR ligands bridge the metal centres in an asymmetric manner, the Pt–μ-C distances being significantly shorter than the corresponding M–μ-C distances. In contrast, the μ-CNCH 2 PO(OEt) 2 ligand of [(OC) 3 Fe{μ-CN–CH 2 PO(OEt) 2 }(μ-dppm)Pt(PPh 3 )] ( 9 ) bridges symmetrically the two metal centres. Furthermore, the molecular structure of cis -[(benzylNC)(OC) 4 W(η 1 -dppm)] ( 8a ) resulting from degradation of 5 has been determined.

Synthesis, Reactivity and Molecular Structures of Bis(diphenylphosphanyl)methane‐Bridged Heterobimetallic Iron−Platinum Isocyanide Complexes: Breaking and Formation of Metal−Metal Bonds

When [(OC)3Fe(μ-CO)(μ-dppm)PtCl2] (1) is allowed to react with stoichiometric amounts of various isocyanides, cleavage of the metal−metal bond occurs, yielding the heterodinuclear isocyanide complexes [(OC)4Fe{μ-dppm}Pt(Cl)2(CNR)] (2a: R = 2,6-xylyl; 2b: R = o-anisyl; 2c: R = benzyl; 2d: R = cyclohexyl; 2e: R = tosylmethyl). Reduction of 2a−2e by NaBH4 in the presence of PPh3 affords the isocyanide-bridged complexes [(OC)3Fe(μ-C=N−R)(μ-dppm)Pt(PPh3)] (3a: R = 2,6-xylyl; 3b: R = o-anisyl; 3c: R = benzyl; 3d: R = cyclohexyl; 3e: R = tosylmethyl). Metathesis of 2a−2d with NaI rapidly results in the formation of [(OC)4Fe{μ-dppm}PtI2(CNR)] (4a−4d), which is slowly transformed under extrusion of CO giving [(OC)2IFe{μ-dppm}(μ-CO)PtI(CNR)] (6a: R = 2,6-xylyl; 6b: R = o-anisyl; 6c: R = benzyl; 6d: R = cyclohexyl), bearing an iodine ligand at the iron center. Due to this intramolecular iodide migration from Pt to Fe, an FeI d7 fragment interacts with a PtI d9 fragment through a covalent bond. Alternatively, 6a−6d are obtained by stoichiometric treatment of [(CO)3Fe(μ-I)(μ-dppm)PtI] (5) with CNR. Single-crystal X-ray diffraction studies are performed on 2d, 2e and 3c as well as on 6d. In the solid state, the two metal centers of 2e remain in close contact (3.862 A), whereas in the case of 2d they are separated by 6.573 A after cleavage of the metal−metal bond by CNR. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Insertion reactions of alkynes and organic isocyanides into the palladium–carbon bond of dimetallic Fe–Pd alkoxysilyl complexes

Insertion of MeO(2)C-C[triple bond]C-CO(2)Me (DMAD) into the Pd-C bond of the heterodimetallic complex [(OC)(3)F[upper bond 1 start]e{mu-Si(OMe)(2)([lower bond 1 start]OMe)}(mu-dppm)P[lower bond 1 end][upper bond 1 end]d(dmba-C)] (2) (dppm = Ph(2)PCH(2)PPh(2), dmba-C = metallated dimethylbenzylamine) and [(OC)(3){(MeO)(3)Si}F[upper bond 1 start]e(mu-dppm)P[upper bond 1 end]d(8-mq-C,N)] (3) (8-mq-C,N = cyclometallated 8-methylquinoline) yielded the sigma-alkenyl complexes [(OC)(3)F[upper bond 1 start]e{mu-Si(OMe)(2)([lower bond 1 start]OMe)}(mu-dppm)P[lower bond 1 end][upper bond 1 end]d{C(CO(2)Me)=C(CO(2)Me)(o-C(6)H(4)CH(2)NMe(2))}] (7) and [(OC)(3)F[upper bond 1 start]e{mu-Si(OMe)(2)([lower bond 1 start]OMe)}(mu-dppm)P[lower bond 1 end][upper bond 1 end]d{C(CO(2)Me)[double bond, length as m-dash]C(CO(2)Me)(CH(2)C(9)H(6)N)}] (8), respectively. The latter afforded the adduct [(OC)(3){(MeO)(3)Si}F[upper bond 1 start]e(mu-dppm)P[upper bond 1 end]d{C(CO(2)Me)=C(CO(2)Me)(CH(2)C(9)H(6)N)}(CNBu(t))] (9) upon reaction with 1 equiv. of Bu(t)NC. The heterodinuclear sigma-butadienyl complexes [(OC)(3)F[upper bond 1 start]e{mu-Si(OMe)(2)([lower bond 1 start]OMe)}(mu-dppm)P[lower bond 1 end][upper bond 1 end]d{C(Ph=C(Ph)C(CO(2)Me)=(CO(2)Me)(o-C(6)H(4)CH(2)NMe(2))}] (11) and [(OC)(3)F[upper bond 1 start]e{mu-Si(OMe)(2)([lower bond 1 start]OMe)}(mu-dppm)P[lower bond 1 end][upper bond 1 end]d{C(Ph)=C(CO(2)Et)C(Ph)=C(CO(2)Et)(CH(2)C(9)H(6)N)}] (13) have been obtained by reaction of the metallate K[Fe{Si(OMe)(3)}(CO)(3)(dppm-P)] (dppm = Ph(2)PCH(2)PPh(2)) with [P[upper bond 1 start]dCl{C(Ph)=C(Ph)C(CO(2)Me)=C(CO(2)Me)(o-C(6)H(4)CH(2)N[upper bond 1 end]Me(2))}] or [P[upper bond 1 start]dCl{C(Ph)=C(CO(2)Et)C(Ph)=(CO(2)Et)}(CH(2)C(9)H(6)N[upper bond 1 end])], respectively. Monoinsertion of various organic isocyanides RNC into the Pd-C bond of 2 and 3 afforded the corresponding heterometallic iminoacyl complexes. In the case of complexes [(OC)(3){(MeO)(3)Si}F[upper bond 1 start]e(mu-dppm)P[upper bond 1 end][upper bond 1 start]d{C=(NR)(CH(2)C(9)H(6)N[upper bond 1 end])}] (15a R = Ph, 15b R = xylyl), a static six-membered C,N chelate is formed at the Pd centre, in contrast to the situation in [(OC)(3)F[upper bond 1 start]e{mu-Si(OMe)(2)([lower bond 1 start]OMe)}(mu-dppm)P[lower bond 1 end][upper bond 1 end]d{C(=NR)(o-C(6)H(4)CH(2)NMe(2))}] (14a R = o-anisyl, 14b R = 2,6-xylyl) where formation of a mu-eta(2)-Si-O bridge is preferred over NMe(2) coordination. The outcome of the reaction of the dimetallic alkyl complex [(OC)(3)F[upper bond 1 start]e{mu-Si(OMe)(2)([lower bond 1 start]OMe)}(mu-dppm)P[lower bond 1 end][upper bond 1 end]dMe] with RNC depends both on the stoichiometry and the electronic donor properties of the isocyanide employed for the migratory insertion process. In the case of o-anisylisocyanide, the iminoacyl complex [(OC)(3)F[upper bond 1 start]e{mu-Si(OMe)(2)([lower bond 1 start]OMe)}(mu-dppm)P[lower bond 1 end][upper bond 1 end]d{C(=N-o-anisyl)Me}] (16) results from the reaction in a 1 : 1 ratio. Addition of three equiv. of o-anisylisocyanide affords the tris(insertion) product [(OC)(3)F[upper bond 1 start]e{mu-Si(OMe)(2)([lower bond 1 start]OMe)}(mu-dppm)P[lower bond 1 end][upper bond 1 end]d{[C(=N-o-anisyl)](3)Me}] (18). After addition of a fourth equivalent of o-anisylNC, exclusive formation of the isocyanide adduct [(OC)(3){(MeO)(3)Si}F[upper bond 1 start]e(mu-dppm)P[upper bond 1 end]d{[C(=N-o-anisyl)](3)Me}(CN-o-anisyl)] (19) was spectroscopically evidenced. In the complex [(OC)(3)F[upper bond 1 start]e{mu-Si(OMe)(2)([lower bond 1 start]OMe)}(mu-dppm)P[lower bond 1 end][upper bond 1 end]d{[C(=N-o-C(6)H(4)COCH(2))](2)Me}] (20), the sigma-bound diazabutadienyl unit is part of a 12-membered organic macrocyle which results from bis(insertion) of 1,2-bis(2-isocyanophenoxy)ethane into the Pd-Me bond of the precursor complex [(OC)(3)F[upper bond 1 start]e{mu-Si(OMe)(2)([lower bond 1 start]OMe)}(mu-dppm)P[lower bond 1 end][upper bond 1 end]dMe]. In contrast, addition of two equivalents of tert-butylisocyanide to a solution of the latter afforded [(OC)(3){(MeO)(3)Si}F[upper bond 1 start]Fe(mu-dppm)P[upper bond 1 end]d{C(=NBu(t))Me}(CNBu(t))] (21) in which both a terminal and an inserted isocyanide ligand are coordinated to the Pd centre. In all cases, there was no evidence for competing CO substitution at the Fe(CO)(3) fragment by RNC. The molecular structures of the insertion products 8 x CH(2)Cl(2) and 16 x CH(2)Cl(2) have been determined by X-ray diffraction.

Synthesis of μ‐C2S44− Cobalt Complexes by Activation of the 1,3,4,6‐tetrathiapentalene‐2,5‐dione, and Electrochemical Study of [(Cp*Co)2(μ‐C2S4)]

The bimetallic complex [Cp(*)Co)2(μ-C2S4)] in which the two metal centres are linked by an ethylenetetrathiolate C2S44− unit, was synthesized in high yield by oxidative addition of 1,3,4,6 tetrathiapentalene-2,5-dione to [Cp(*)Co(CO)2]. The X-ray crystal structure of the intermediate product Cp*Co(dmid) (dmid2− = 4,5-disulfanyl-1,3-dithiol-2-onate) is presented. The electrochemical behaviour of the [(Cp*Co)2(μ-C2S4)] complex was studied in detail in the oxidative range. This study has shown that the nature of the product obtained after oxidation depends on the presence of complexing agent in the solution. The mechanism has been elucidated in a CH2Cl2 solution in the presence of P(OMe)3. In addition, chemical oxidation was conducted with several oxidizing agents (Br2, TCNQF4, and AgBF4). The molecular structure of the tetrathiooxalate bridged complex [(Cp*Co{P(OMe)3})2(μ-C2S4)](BF4)2 was established by an X-ray diffraction study. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Crystal structure of tricarbon­yl(μ-di­phenyl­phosphido-κ2P:P)(methyl­diphenyl­silyl-κSi)bis(tri­phenyl­phosphane-κP)iron(II)platinum(0)(Fe—Pt)

The title compound belongs to the large family of heterodinuclear phosphide-bridged complexes. The Fe—Pt bond is of 2.7738 (4) Å and there is an unprecedented arrangement of the silyl ligand in a trans-position with respect to the metal–metal vector in the family of phosphide-bridged iron–platinum heterobimetallics.

[μ-Bis(diphenyl­phosphan­yl)methane]­tricarbon­yl(μ-p-toluene­sulfonyl­meth­yl isocyanato)(triphenyl­phosphane)ironplatinum(Fe—Pt)

The title compound, [FePt(C9H9NO2S)(C18H15P)(C25H22P2)(CO)3], represents a rare example of an isonitrile-bridged heterobimetallic complex (here Pt and Fe) and is an interesting precursor for the preparation of heterodinuclear μ-aminocarbyne complexes, since the basic imine-type N atom of the μ2-C=N–R ligand readily undergoes addition with various electrophiles to afford iminium-like salts. In the crystal, the almost symmetrically bridging μ2-C=N-R ligand (neglecting the different atomic radii of Fe and Pt) is strongly bent towards the Fe(CO)3 fragment, with a C=N-R angle of only 121.1 (4)°.