Diene–iridium–tin complexes. Comparison of conjugated versus non-conjugated dienes and trimethyltin versus trichlorotin as ligands. Ring opening metathesis polymerization of norbornene by Ir(1,5-cycloocta-diene)2SnCl3

Heavy metalla vinyl-cations show metal-Lewis acid cooperativity in reaction with small molecules (NH3, N2H4, H2O, H2)

Halide abstraction from tetrylidene complexes [TbbE(Br)IrH(PMe₃)₃] [E = Ge (1), Sn (2)] and [Ar*E(Cl)IrH(PMe₃)₃] gives the salts [TbbEIrH(PMe₃)₃][BAr^F ₄] [E = Ge (3), Sn (4)] and [Ar*EIrH(PMe₃)₃][BAr^F ₄] [E = Ge (3'), E = Sn (4')] (Tbb = 2,6-[CH(SiMe₃)₂]₂-4-(t-Bu)C₆H₂, Ar* = 2,6-Trip₂C₆H₃, Trip = 2,4,6-triisopropylphenyl). Bonding analysis suggests their most suitable description as metalla-tetrela vinyl cations with an Ir[double bond, length as m-dash]E double bond and a near linear coordination at the Ge/Sn atoms. Cationic complexes 3 and 4 oxidatively add NH₃, N₂H₄, H₂O, HCl, and H₂ selectively to give: [TbbGe(NH₂)IrH₂(PMe₃)₃][BAr^F ₄] (5), [TbbE(NHNH₂)IrH₂(PMe₃)₃][BAr^F ₄] [E = Ge (7), Sn (8)], [TbbE(OH)IrH₂(PMe₃)₃][BAr^F ₄] [E = Ge (9), Sn (10)], [TbbE(Cl)IrH₂(PMe₃)₃][BAr^F ₄] [E = Ge (11a), Sn (12a)], [TbbGe(H)IrH₂(PMe₃)₃][BAr^F ₄] (13), [TbbSn(μ-H₃)Ir(PMe₃)₃][BAr^F ₄] (14), and [TbbSn(H)IrH₂(PMe₃)₃][BAr^F ₄] (15). 14 isomerizes to give 15via an 1,2-H shift reaction. Hydride addition to cation 3 gives a mixture of products [TbbGeHIrH(PMe₃)₃] (16) and [TbbGeIrH₂(PMe₃)₃] (17) and a reversible 1,2-H shift between 16 and 17 was studied. In the tin case 4 the dihydride [TbbSnIrH₂(PMe₃)₃] (18) was isolated exclusively. The PMe₃ and PEt₃ derivatives, 18 and [TbbSnIrH₂(PEt₃)₃] (19), respectively, could also be synthesized in reaction of [TbbSnH₂]^- with the respective chloride [(R₃P) _n IrCl] (R = Me, n = 4; R = Et, n = 3). Reaction of complex 19 with CO gives the substitution product [TbbSnIrH₂(CO)(PEt₃)₂] (20). Further reaction with CO results in hydrogen transfer from the iridium to the tin atom to give [TbbSnH₂Ir(CO)₂(PEt₃)₂] (21). The reversibility of this ligand induced reductive elimination transferring 20 to 21 is shown.

Crystal structure of chlorido-bis-[(1,2,5,6-η)-cyclo-octa-1,5-diene]iridium(I)

The title complex, [IrCl(C8H12)2], was synthesized directly from the reaction of IrCl3·3H2O with a large excess of cod (cod = cyclo-octa-1,5-diene) in alcoholic solvent. Large yellow needles were obtained by the slow cooling of a hot solution. Based on the positions of the chloride ligand and the mid-points of the four C=C bonds, the mol-ecule adopts a five-coordinate geometry that is midway between square pyramidal and trigonal bipyramidal. The material crystallizes in the ortho-rhom-bic space group Pbca with one mol-ecule per asymmetric unit in a general position and shows no significant inter-molecular inter-actions. Individual mol-ecules are aligned along [010], and these rows form a pseudo-hexa-gonal packing arrangement.