Laurence J. Gregoriades

One-Dimensional Polymers Based on Silver(I) Cations and Organometallic cyclo-P3 Ligand Complexes

The synthesis and characterization of the first supramolecular aggregates incorporating the organometallic cyclo-P3 ligand complexes [CpRMo(CO)2(eta3-P3)] (CpR=Cp (C5H5; 1a), Cp* (C5(CH3)5; 1b)) as linking units is described. The reaction of the Cp derivative 1a with AgX (X=CF3SO3, Al{OC(CF3)3}4) yields the one-dimensional (1D) coordination polymers [Ag{CpMo(CO)2(mu,eta3:eta1:eta1-P3)}2]n[Al{OC(CF3)3}4]n (2) and [Ag{CpMo(CO)2(mu,eta3:eta1:eta1-P3)}3]n[X]n (X=CF3SO3 (3a), Al{OC(CF3)3}4 (3b)). The solid-state structures of these polymers were revealed by X-ray crystallography and shown to comprise polycationic chains well-separated from the weakly coordinating anions. If AgCF3SO3 is used, polymer 3a is obtained regardless of reactant stoichiometry whereas in the case of Ag[Al{OC(CF3)3}4], reactant stoichiometry plays a decisive role in determining the structure and composition of the resulting product. Moreover, polymers 3a, b are the first examples of homoleptic silver complexes in which Ag(I) centers are found octahedrally coordinated to six phosphorus atoms. The Cp* derivative 1b reacts with Ag[Al{OC(CF3)3}4] to yield the 1D polymer [Ag{Cp*Mo(CO)2(mu,eta3:eta2:eta1-P3)}2]n[Al{OC(CF3)3}4]n (4), the crystal structure of which differs from that of polymer 2 in the coordination mode of the cyclo-P3 ligands: in 2, the Ag+ cations are bridged by the cyclo-P3 ligands in a eta1:eta1 (edge bridging) fashion whereas in 4, they are bridged exclusively in a eta2:eta1 mode (face bridging). Thus, one third of the phosphorus atoms in 2 are not coordinated to silver while in 4, all phosphorus atoms are engaged in coordination with silver. Comprehensive spectroscopic and analytical measurements revealed that the polymers 2, 3a, b, and 4 depolymerize extensively upon dissolution and display dynamic behavior in solution, as evidenced in particular by variable temperature 31P NMR spectroscopy. Solid-state 31P magic angle spinning (MAS) NMR measurements, performed on the polymers 2, 3b, and 4, demonstrated that the polymers 2 and 3b also display dynamic behavior in the solid state at room temperature. The X-ray crystallographic characterisation of 1b is also reported.

Formation of Spherical Giant Molecules and Dynamic Behaviour of Supramolecular Assemblies Based on Pn-Ligand Complexes

We report herein on our concept of using En-ligand complexes (E = P, As) as linking units for the creation of novel supramolecular ensembles. The reaction of these complexes with Group 11 metal salts of coordinating anions leads to the formation of insoluble oligomers, 1D and 2D polymers as well as soluble spherical nanoscaled clusters. In contrast, the reaction of En-ligand complexes with Group 11 metal salts of weakly coordinating anions yields soluble oligomers and polymers, which display monomer-oligomer equilibria in solution.

Activation of C-H bonds mediated by Mo[triple bond]Mo moieties in heterobimetallic Zn/O/Mo clusters.

Heterobimetallic drive and cooperativity lead to a striking scenario for C-H bond activation and heteroaggregation involving Mo(III) dimers. Reaction of (RO)(3)Mo[triple bond]Mo(OR)(3) with molar excess of ZnMe(2) at-78 degrees C affords the novel mixed Zn, Mo oxo clusters [Mo(2)(MeZn)(6)(mu(2)-Me)(mu(3)-CH(2))(2)(OR)(7)] 1 (R = neopentyl) and 2 (R = cyclohexyl) preserving the Mo[triple bond]Mo triple bond, while the same reaction performed at ambient temperature gives rise to the related cluster [Mo(2)(MeZn)(6)(mu(2)-CH(2))(mu(3)-CH(2))(2)(OR)(6)] 3. These complexes represent the first examples of heterobimetallic Mo[triple bond]Mo complexes with bridging methyl and methylene groups and agostic C-H-->Mo interactions, as well as penta-coordinate carbon. The complexes 1-3 were characterized by elemental analyses, multinuclear NMR and single-crystal X-ray diffraction analysis.