R. Kergoat

Réactions d'insertion du cyanoacétylène et du dicyanoacétylène dans les deux liaisons métalhydrogène des dihydrures [(C5H5)2MH2] (M Mo ou W)

Abstract Only alkyne or alkene insertion reactions into one MH bond of [(C 5 H 5 ) 2 MH 2 ] (M  Mo or W) have been reported up to now. The insertion of alkynes with low steric hindrance, cyanoacetylene (HCCCN) and dicyanoacetylene (NCCCCN) into both MH of [(C 5 H 5 ) 2 MH 2 ] bonds are described in this paper. The first, as well as the second insertion of the same alkyne (either HCCCN or NCCCCN) is stereoselective. The (C 5 H 5 ) 2 M(H)AAH or (C 5 H 5 ) 2 M(AAH) 2 complexes are formed. In the case of mixed diinsertion complexes, ([(C 5 H 5 ) 2 M(σ-C 3 H 2 N)(σ-C 4 HN 2 )]) containing both cyanoacetylene and dicyanoacetylene, the geometry of the final products depends on the order of addition of the reactants. Thus, the insertion of (HCCCN) into [(C 5 H 5 ) 2 MH(σ- trans -C(CN)CHCN)] is stereoselective, while in the reaction of (NCCCCN) with [(C 5 H 5 ) 2 MH(σ-C(CN)CH 2 ] two stereoisomers [(C 5 H 5 ) 2 M(σ- trans - and - cis -C(CN)CHCN)(σ-C(CN)CH 2 )] are formed. Insertions of cyanoacetylene and dicyanoacetylene into a MH bond of (C 5 H 5 ) 2 M(H)AAH complexes (AA  HCCCF 3 , CH 3 O 2 CCCCO 2 CH 3 , NCCHCHCN, CH 3 O 2 CCHCHCO 2 CH 3 ) are also reported. The stereochemistry of the various complexes is proposed on the basis of 1 H and 13 C NMR spectra, and the mechanisms of the various insertion reactions are discussed.

Bis-cyclopentadienyl molybdenum and tungsten compounds with mercury-transition metalmercury bonds. Part I. Chemical, spectroscopic and structural studies of halogeno- and thiolato-derivatives

Abstract Cp 2 MH 2 (M = Mo and W) react with HgX 2 (X = Cl, Br, I, SCN, OAc and CN) salts, giving insoluble compounds which have the general formula Cp 2 M(HgX) 2 ·xHgX 2 (I) (x = 0, 1 3 , 1 2 , 2 3 and 1). These compounds were characterized by using IR and, for some of them, Raman spectroscopy. Frequencies of Hg-X vibrations are discussed in the light of an ‘adduct type’ structure. MoHg and WHg bands are detected in the Ramam spectra near 130–140 cm −1 . An intermediate polymeric compound (Cp 2 MoHg) n (II) was isolated and characterized by IR spectrum and unit cell parameters. All compounds (I) and (II) react with thiolates giving non-adduct: i) compounds Cp 2 M(HgSR) 2 (R = Me, Et, i Pr and n Pr) (III) soluble in organic solvents and ii) insoluble compounds [Cp 2 MHg 2 (SR)]X(X = Cl, Br) (IV). Compounds (IV) with X = Cl also crystallize from solutions of (III) in chloroform. Insoluble Cp 2 M(HgSR) 2 (R = pheynl or pyrimidine) compounds were obtained by the reaction of (I) with corresponding thiolates. IR spectra of all these derivatives were recorded showing similar features to those of the compounds (I). ( 1 H), ( 13 C) and ( 99 Hg) NMR spectra of soluble complexes (III) were recorded. The structure of [Cp 2 MoHg 2 (SEt)] Cl determined by X-ray analysis is built of infinite chains of Cp 2 MoHg 2 moieties and thiolates bridging two mercury atoms from the adjacent Cp 2 MoHg 2 units and of essentially ionic chlorides.

Transition metal-cyanocarbon chemistry: IX. Reactions of monocyanoacetylene with dicarbonylcyclopentadienylmethylthiolatoiron(II). Crystal structures of [FeC(O)C(CN)CH(SCH3) (η5-C5H5)(CO)] and of μ-η2-Fe(CCCN)(η5-C5H5)(CO)2][Co(CO)3]2

Abstract The reaction of [Fe(η5-C5H5)(SCH3)(CO)2] with monocyanoacetylene (HCCCN) in THF at room temperature gives the acetylide [Fe(CCCN)(η5-C5H5)(CO)2] (1, the acylic species [ FeC(O)C(CN)CH(S CH3)(η5-C5H5)(CO)] (2), the binuclear complex [Fe(η5-C5H5)(CO)2C(CN)C(SCH3)Fe(η5-C5H5)(CO)2] (3), and the disubstituted olefin Z-(NC)CHCH((SCH3) (4. If the HCCCN is condensed on to a frozen solution of the thiolato complex and the mixture then allowed to warm up, the acylic compound 2 is not isolated. Irradiation of 1 and 3 in the presence of PPh3 in THF gives the substituted complex [Fe(CCCN)(η5-C5H5)(CO)(PPh3)] (6)_and [Fe(η5-C5H5)(CO)2C(CN)C(SCH3)Fe(η5-C5H5)(CO)(PPh3)] (10). Cycloaddition of tetracyanoethylene on 1 and 6 gives the corresponding complexes [fe( CC(CN)C(CN) 2 C (CN)2(η5-C5H5)(CO)(L)] (L = CO (7) or PPh3 (8). Under UV irradiation 8 is converted into Fe(η 3 -C(CN) 2 C(CN)C C(CN)2(η5-C5H5)(PPh3)] by loss of CO. Complex 1 reacts with Co2(CO)8 to form the [μ-η2-Fe(CC-CN)(η5-C5H5)(CO)2][Co(CO)3]2 (5). The structures of 2 and 5 have been determined by X-ray diffraction.

Transition metal-cyanocarbon chemistry: VII. Reactions of mono- and di-cyanoacetylenes with tricarbonylcyclopentadienylmethylthiolatotungsten(II). Formation of phosphorus ylide complex [(C5H5)(CO)2W(CH(P(C6H5)3)C(CN)SCH3)]. Crystal structure of [(C5H5)(CO)2(P(C6H5)3)-W(C(O)C(CN)CHSCH3)·CH2Cl2]☆

Abstract Reactions of (C 5 H 5 )(CO) 3 W(SMe) with cyano-activated alkynes RCCCN with R  H or CN give heterometallacyclic complexes (C 5 H 5 )(CO) 2 W(C(O)C(CN)C(R)S Me) (R  H ( 2 ) or CN ( 6 )) or for R  H, an insertion σ-vinylic complex [(C 5 H 5 )(CO) 3 W(CHC(CN)SMe)] ( 3 ). Irradiation of 3 in the presence of PPh 3 in THF gives the ylide complex (C 5 H 5 )(CO) 2 W(η 2 -CH(PPh 3 )C(CN)SMe) ( 5 ), whereas 2 under such conditions gives an η 1 -acylic complex [(C 5 H 5 )(CO) 2 PPh 3 W(C(O)C-(CN)CHSMe)] ( 4 ). The structure of 4 has been determined by X-ray diffraction.

Complexes biscyclopentadienyles avec des liaisons metal de transitionmercure ☆: III. Structure de deux phases de (C5H5)2Mo(HgSC2H5)2; etude de la distribution electronique dans les complexes (C5H5)2MoX2 par resonance magnetique nucleaire

Abstract (C5H5)2Mo(HgSC2H5)2 crystallizes in two different forms; a red one (A) which is insoluble in the usual organic solvents, the other one (B) is orange and soluble. Their structures were determined by X-ray diffraction. A: P21/c, a 10.342(5), b 17.757(10), c 10.193(6) A, β 113.39(4)°, Z = 4; B: C2/c, a 31.503(8), b 7.986(3), c 20.843(11) A, β 97.87(3)°, Z = 12. The molecular geometry is nearly the same in the two phases (MoHg: 2.677 A (A) and 2.676 A (B); HgS: 2.43 A (A) and (B): HgMoHg; 70.8° (A) and 73.1° (B); MoHgS: 167.6° (A) and 171.2° (B); C5H5MoC5H5: 140.5° (A) and 137.8° (B), whereas the overall structure is different. “Dimeric units” exist in A. The shortest distances HgS between two different molecules in the “dimeric unit” are equal to 3.17 A. An infinite system of mercurysulfur interactions is shown to exist in the form B(HgS: 3.32–3.33 A). The electronic structure of the (C5H5)2Mo(HgSR)2 compounds is discussed on the basis of 1H, 13C, 199Hg and 95Mo NMR results and compared with the geometrical parameters. A relation between the nature of the X-ligands in the (C5H5)MoX2 complexes (X = O, Cl, S, H, Hg), the C5H5MoC5H5 angle and the 1H(C5H5) chemical shifts is evident.

Transition metal-cyanocarbon chemistry X. Reactions of monocyanoacetylene and dicyanoacetylene with organometallic compounds of cobalt(I) and nickel(II). Crystal structure of [Co(CCCN)2(η5-C5H5)(P(C6H5)3)]☆

Abstract The reaction of monocyanoacetylene (HCCCN) with [Co(η 5 -C 5 H 5 )(P(C 6 H 5 ) 3 ) 2 ] gives the vinylacetylide [Co(CCCN)(CHCH(CN))(η 5 -C 5 H 5 )(P(C 6 H 5 ) 3 )] ( 1 ) and the diacetylide [Co(CCCN) 2 (η 5 -C 5 H 5 )(P(C 6 H 5 ) 3 )] ( 2 ). The crystal structure of the latter has been established by an X-ray diffraction study. Two conformers of 1 are formed in a ratio depending on conditions. In 1 a PPh 3 ligand can be replaced by (CH 3 ) 3 SiCCSi(CH 3 ) 3 , which acts as a π-bonded ligand in the product, [Co(CCCN)(CHCH(CN))(η 5 -C 5 H 5 )(η 2 -(CH 3 ) 3 SiCCSi(CH 3 ) 3 )] ( 3 ). Treatment of 1 with I 2 gave (Co(η 5 -C 5 H 5 )(I) 2 (P(C 6 H 5 ) 3 )] ( 6 ) and CH(CN)CH-C(CN)CHI ( 5 ). The major product of the reaction of [Co(η 5 -C 5 H 5 )(P(C 6 H 5 ) 3 ) 2 ] with dicyanoacetylene (NCCCCN) was the 1,6-diphosphorane (C 6 H 5 ) 3 PC(CN)C(CN)C(CN)C(CN)C(CN)C(CN)P(C 6 H 5 ) 3 . [Co(η 5 -C 5 H 5 )(η 4 -C 5 H 5 (CCCN))] ( 7 ) was isolated from the reaction of monocyanoacetylene with [Co(η 5 -C 5 H 5 )(η 4 -C 5 H 6 )]. Cyanoalkynes bridge two nickel atoms in [μ-(HCCCN)][Ni(η 5 -C 5 H 5 )] 2 ( 8 ) and [μ-(NCCCCN)][Ni(η 5 -C 5 H 5 )] 2 ( 9 ), which were formed in the reaction of nickelocene with HCCCN and NCCCCN, respectively.

Transition metal-cyanocarbon chemistry: VI. Insertions of cyano- and dicyano-acetylenes into the iron-hydride bonds in (C5H5)(CO)LFeH (L CO, PPh3) and [(C5H5)(CO)FeH]2 [μ-(C6H5)2PCH2CH2P(C6H5)2] complexes☆

Abstract Monocyanoacetylene (HCCCN, mca) and dicyanoacetylene (NCCCCN, dca) have been shown to insert into the FeH bonds of various mononuclear and dinuclear iron hydrides. In the presence of dca, [(η 5 -C 5 H 5 )(CO) 2 FeH] and [(η 5 -C 5 H 5 )(CO)(PPh 3 )FeH] give [(η 5 -C 5 H 5 )(CO) 2 Fe(σ-(Z)-C(CN)CH(CN)] and [(η 5 -C 5 H 5 )(CO)(PPh 3 )Fe(σ-(Z)-C(CN)CH(CN)] respectively. The reaction involving [(η 5 -C 5 H 5 )(CO)(PPh 3 )FeH] provides the first evidence for non-regioselectivity of an insertion of mca; the isomers [(η 5 -C 5 H 5 )(CO)(PPh 3 )Fe(σ-(Z)-CHCH(CN)] and [(η 5 -C 5 H 5 )(CO)(PPh 3 )Fe(σ-C(CN)CH 2 )] being obtained in a 4/1 ratio. However regioselectivity is observed for insertion of mca into the FeH bonds of dinuclear [(η 5 -C 5 H 5 )(CO)FeH] 2 (μ-dppe) (dppe = 1,2-bis(diphenylphosphido)ethane); in this case the CN groups are attached only to the C α carbon atom. The reaction of dca with the dinuclear hydride gives products analogous to those from the mononuclear ones. The mechanisms of these various insertions are discussed in terms of the degree of hydridic nature of the hydridic hydrogen in the initial iron complexes.

New observations on dicyclopentadienylmolybdenum complexes derived from dimethyl acetylenedicarboxylate. Crystal structure of [(η5-C5H5)2MCO2CH3]

Abstract Addition of chloroform to a solution of (η 5 -C 5 H 5 ) 2 MoH 2 and dimethylacetylenedicarboxylate (CH 3 CO 2 CCCO 2 CH 3 ) in THF at 0°C gives two new complexes: (i) chloro-αs-alkenyl (η 5 -C 5 H 5 ) 2 MoCl[Z-C(CO 2 CH 3 )CH(CO 2 CH 3 )] and (ii) metallacyclic [(þ 5 -C 5 H 5 ) 2 M oOC(O)CHC CO 2 CH 3 ]. An X-ray diffraction study of the latter product revealed the presence of one water molecule per one organometallic molecule in the unit cell: space group P 2 1 , a 12.111(9), b 7.374(2), c 7.830(5) A, β 93.43(4)°, Z = 2. The MoC bond length is 2.180(6) A. A mechanism involving an intramolecular elimination of CH 4 from the initially formed insertion product (η 5 -C 5 H 5 ) 2 MoH[Z-C(CO 2 CH 3 )CH(CO 2 CH 3 )] is proposed for its formation.

Transition metalcyanocarbon chemistry. Part V. Crystal and molecular structure of biscyclopentadienyl complexes containing a σ-cyanoalkyl and a σ-cyanoalkenyl ligand: (η5-C5H5)2Mo[S(C6H5)](σ-CH(CN)CH3) and (η5-C5H5)2Mo(S2CN(C2H5)2)(σ-C(CN)CH2)

Abstract The crystal structures of the title complexes were determined by X-ray diffraction analysis. (η5-C5H5)2Mo(SPh)(σ-CH(CN)CH3)—(4) crystallizes in the monoclinic space group P21/c with a = 16.861(3), b = 7.570(4), c = 14.054(4) A, β = 110.28(1)°, Z = 4. (η5-C5H5)2Mo(S2CN(C2H5)2)(σ-C(CN)CH2)—(3) crystallizes in the monoclinic space group P21/n with a = 21.943(3), b = 7.545(2), c = 11.325(1) A, β = 98.33(1)°, Z = 4. The σ-alkyl ligand in (4) with MoC bond length of 2.306(3) A has a perpendicular orientation with respect to the line bisecting the C5H5MoC5H5 and SMoC angles, but the conformation of the σ-alkenyl ligand in (3), with the corresponding MoC bond length of 2.232(4) A, is parallel with respect to this line.

Synthesis of secondary allenylidene-molybdenum complexes with a ferrocenyl substituent from carbenium ions species stabilized by two organometallic moieties

The monoallenylidene complex [Cp2Mo2(CO)4{μ−σ:η2−CCC(Fc)(H)}] (5) and the diallenylidene complex [{Cp2Mo2(CO4(μ−σ:η2−CCC(H))}2Fc] (6) have been obtained from the corresponding monocarbenium ion [Cp2Mo2(CO)4{μ−η2:η3−HCCC(H)(Fc)}][BF4] and the dicarbenium ion [{Cp2Mo2(Co)4(μ−η2:η3−HCCC(H)}2Fc] [{BF4}2] (4) respectively, and their spectroscopic data are determined.