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Unusual suspect: The complex [(Cp*Mo)2(,3-P3)(,2-PS)] reacts with CuI and Ag[Al{OC(CF3)3}4] to form two novel linear polymers (see structure of CuI derivative; Cu light blue, I violet, Mo blue, P pink, S yellow). Even with X-ray crystallographic data available, the fact that the sulfur atoms in these polymers do not coordinate to the Group 11 metal centers could only be established with the help of 31P MAS NMR spectroscopy. Cp*=C5Me5

International audience; The novel cluster anion [Co11Te5(CO)15]- ([3]-) has been isolated and structurally characterized as part of the salt [Cp*2Nb(CO)2][3] (Cp* = C5Me5). The cobalt-centered Co10 pentagonal prism is surrounded by a shell of two μ5-Te, three μ4-Te ligands, and 15 CO groups in terminal, symmetrical, and σ-semibridging bonding modes. The hybrid carbonyl-telluride character of the ligand shell is reflected in the solid state by a one-dimensional assembly of polyhedral prisms along a backbone of [Cp*2Nb(CO)2]+ cations. Electrochemical studies reveal the presence of four redox couples of [3]n (n = −1 to −5). The electronic structures of various metal-centered and empty pentagonal-prismatic (PP) M10 clusters (M = Co, Ni) are calculated and compared to those of pentagonal-antiprismatic (PA) M10 structures. Closed-shells of 152 and 156 metal valence electrons, respectively, are found to determine the electronic structures and chemical properties of these geometries. From these considerations, magnetic properties have been predicted. They have been verified for the [Co11Te7(CO)10]- cluster anion, which exhibits a singlet−triplet gap of 0.318 kcal/mol.

Ein ungewöhnlicher Baustein: Der Komplex [(Cp*Mo)2(,3-P3)(,2-PS)] bildet mit CuI und Ag[Al{OC(CF3)3}4] neue lineare Koordinationspolymere (siehe die Struktur das CuI-Derivats im Kristall; Cu hellblau, I violett, Mo blau, P rosa, S gelb). Erst anhand der 31P-MAS-NMR-Spektren konnte gezeigt werden, dass in den Polymerketten die Schwefelatome nicht an die Gruppe-11-Metalle koordinieren.

The coordination behavior of [(Cp*Mo)2As2S3] (3) (Cp* = C5Me5) toward Cu(I) halides was investigated. One dimensional polymers of the general formula [(Cp*Mo)2As2S3(CuHal)2]n (Hal = Cl, 4; Br, 5) and an oligomer of composition [{(Cp*Mo)2As2S3}3(CuI)7] (6) formed upon the reaction of 3 with the corresponding copper halide. All of the compounds were characterized by ESI−MS, elemental analysis, and single-crystal X-ray crystallography. The solid-state structures of 4 and 5 are isostructural and contain 1D S-shaped chains. This peculiar folding is achieved by alternating planar and folded Cu2Hal2 rings linked together by the central monosulfide bridge of the middle deck of the organometallic unit. The structure of 6 is characterized by a novel [CuI]7 aggregate, which forms a very flat Cu6I3S3 bowl along with three integrated peripheral [(Cp*Mo)2As2S3] building blocks. In contrast to earlier findings, the middle deck of the organometallic units consists in all structures of two trapezoidal AsS dumbbells and one monosulfide ligand.

As3 makes the connection: [Cp*Mo(CO)2(3-As3)] reacts with Ag[Al{OC(CF3)3}4] to yield a novel dimeric complex featuring the cyclo-As3 ligand in an unusual face-bridging coordination mode. Analytical data and DFT calculations support the existence of a monomer-dimer equilibrium in solution (see scheme). [Cp*Mo(CO)2(3-As3)] also reacts with CuX (X=Cl, Br, I) to yield insoluble dimers consisting of planar Cu2X2 moieties.

The reaction of Cp+2bBH4 with sulfur gives two isomers of composition Cp+2NbS2H (3, 4) and Cp+2NbS3H (5). The structures of 3-5 have been investigated by IR and H-1 NMR spectroscopic means. X-Ray diffraction analyses have been performed on 3 and 4. These investigations demonstrate that 3 and 4 are niobocene derivatives, in which either a eta2-S-2(2)--ligand and a hydride (3) or a S2- and a SH- ligand (4) are attached to the Nb center. Complex 3 can be transformed thermally into 4 by a S-S bond rupture, followed by the insertion of sulfur into the Nb-H bond. The polynuclear compounds Cp+3Nb3S7 (6) and Cp+3Nb3S12 (7) can be formed by the reaction of 3 with S8. The role of polysulfide intermediates is discussed.

NbCl5 reacts with NaBH4 and LiCp+ (Cp+ = EtMe4C5) dependent on the stoichiometry and temperature to give Cp+2NbCl2 (1), CP+2Nb2Cl2(B2H6)(2), CP+2NbBH4(3a) and Cp+ 2Nb2(B2H6)2 (4a). With a large excess of NaBH4, Cp+ 2NbCl2 gives 2 at 25-degrees-C, which reacts further with NaBH 4 to give 4a. The synthesis of the deep violet, very stable 4a can be generalised by using C5Me5Li and tBUC5H4Li, respectively. Compounds 1-4 are characterised by means of IR, H-1, and heteroatom NMR spectra. An X-ray structure analysis was carried out with 4a. Whereas 1 and 3 are analogous to already known complexes, in 2 and 4a the B2H, dianion (which is not stable in the free state) is present as a bridging ligand, oriented perpendicularly with respect to the Nb-Nb axis. So far, the highest nuclear magnetic Nb-93 shielding has been observed for compounds 4, extending the range of known delta(Nb-93) values by 2500 ppm. The temperature dependence of the linewidths of both the B-11 and the Nb-93 NMR signals of 4c allows evaluation of the magnitude of J((NbB)-Nb-93-B-11 = 50 +/- 10 Hz.

The reaction of the differently substituted cyclopentadienyl complexes L2M2(CO)4 with sulfur is investigated with respect to the ligand L (etmcp = ethyltetramethylcyclopentadienyl, tbcp = t-butylcyclopentadienyl, ipcp = isopropylcyclopentadienyl) and the metal M (Cr, Mo, W). For M = Cr the only isolated product is etmcp2Cr2S5. For M = Mo three isomers A, D, E of composition L2Mo2S4 (L = ipcp, etmcp) are formed whereas only two isomers (A, D) exist for L = tbcp. Only two isomers (D, E) of composition L2W2S4 are formed in the system L2W2(CO)4/S8, a further product is L2W2(CO)2S3 for L = etmcp. Structural characterisation of all compounds was achieved by IR, H-1, and Mo-95 NMR spectroscopy, whereas the structures of syn-etmcp2M2(mu-S)2S2 (M = Mo, W) were determined by X-ray crystallography, the result of which allows the correction of a previous structure assignment. It is further shown that a thermal equilibrium exists between L2Mo2(mu,eta-2-S2)(mu-S)2 (A) and syn-L2Mo2(mu-S)2S2 (D) which depends strongly on the ligands.

The reaction of bcpmCr2(CO)6 (bcpm = biscyclopentadienylmethane) with sulfur gives in a stepwise reaction the complexes bcpmCr2(CO)4S (2) and bcpm2Cr4S4 (3). The products were investigated by IR and low temperature H-1 NMR spectroscopy. The H-1 NMR spectra of 2 show upon cooling a dynamic process similar to that in the starting material. It is ascribed to a topomerization process in the bridging ligand. The cluster 3 which belongs to the heterocubane type exhibits a magnetic behavior which is inbetween that of the antiferromagnetic clusters of type CP4Cr4O4 (CP = any substituted eta-5-C5H5 ring) and the diamagnetic CP4Cr4S4 cubanes.

The reaction of Cp2*Mo2S4I2(Cp* = eta(5)-C5Me5) with two equivalents of NaSR (R = Me, (i)Pr, (t)Bu, Ph) gives the complexes Cp2*Mo2(mu,eta(1)-SSR)2(mu-S)2 (2a-d) in nearly quantitative yields. The compounds have been investigated spectroscopically and in the case of R = Ph (2d) by means of X-ray diffraction analysis. The results show the presence of two eta(1)-PhSS- bridges (d(s-s) 2.139(2) angstrom) and that exclusively the trans-isomer is formed. All sulfur atoms lie in one plane perpendicular to the Mo-Mo axis and bisecting it.