Donald K. Drummond

Variable coordination numbers in crystalline bis(pentamethylcyclopentadienyl)samarium oxide, iodide and alkoxide complexes

Abstract Three crystallographically characterized organosamarium complexes containing formally {itx}-coordinate trivalent samarium have been recrystallized under appropriate conditions to give formally {itx} + 1-coordinate species. The structures of these complexes have been determined and are compared with the {itx}-coordinate structures. The implications of this structural flexibility on the steric factors which are very important in organolanthanide reactivity are discussed. Recrystallization of the seven-coordinate dihydroindenoindene diolate complex [(C{in5}Me{in5}){in2}Sm]{in2}O{in2}C{in16}H{in10} ({bd1}) from THF gives the eight-coordinate solvate [(C{in5}Me{in5}){in2}Sm(THF)]{in2}O{in2}C{in16}H{in10} ({bd2}) which crystallizes as a THF solvate in the space group {itP}2{in1}/{itn} with {ita} = 10.811(4), {itb} = 13.878(4), c = 25.114(7) \rA, \gb = 98.77(7)\dg and {itD}{incalc.} = 1.15 g cm{su\t-3} for {itZ} = 2. Least-squares refinement on the basis of 2208 observed reflections led to a final {itR} valueof 0.049. In {bd2}, two (C{in5}Me{in5}){in2}Sm bent metallocene units are coordinated to the O{in2}C{in16}H{in10} framework via SmO bonds of 2.099(9) \rA. Each Sm centre is also ligated by a THF molecule with a SmO distance of 2.490(9) \rA. Both {bd1} and {bd2} have similar O{in2}C{in16}H{in10} units but {bd2} has larger average SmC distances (2.75(2) vs 2.70(3) \rA) and a smaller (ring centroid)Sm(ring centroid) angle (132.9 vs 139.8\dg). Recrystallization of [(C{in5}Me{in5}){in2}Sm]{in2}(\gm-O) ({bd3}) from toluene in the presence of {bdCNCMe}{in3}, forms [(C{in5}Me{in5}){in2}Sm(CNCMe{in3})]{in2}(\gm-O) ({bd4}) which crystallizes in the space group {itP}2{in1}/{itc} with {ita} = 27.265(10), {itb} = 13.946(5), {itc} = 15.505(5)\rA, \gb = 101.25(3)\dg and {itD}{incalc.} = 1.28 g cm{su\t-3} for {itZ} = 4. Least-squares refinement on the basis of 8275 observed reflections led to a final {itR} value of 0.064. Like {bd3}, {bd4} has short SmO distances, 2.101(7) \rA, and a nearly linear (174.3(4)\dg) SmOSm angle. {bd4} has a larger SmC(ring) average (2.80(1) vs 2.73(1) \rA) and a smaller (ring centroid)Sm(ring centroid) angle (133.5 vs 137.2\dg). Recrystallization of (C{in5}Me{in5}){in2}SmI(THF) ({bd5}) in the presence of one equivalent of 1,5-pentamethylenetetrazole (C{in6}H{in10}N{in4}) gives the complex (C{in5}Me{in5}){in2}SmI(C{in6}H{in10}N{in4}) ({bd6}) which crystallizes in space group {itP}2{in1}/{ita} with {ita} = 15.969(10), {itb} = 10.741(10), {itc} = 17.768(7)\rA, \gb = 108.81(4)\dg and {itD}{incalc.} = 1.58 g cm{su\t-3} for {itZ} = 4. Least-squares refinement on the basis of 3327 observed reflections led to a final {itR} value of 0.061. In addition to the attachments of the two C{in5}Me{in5} rings and the iodide ligand to Sm, two of the nitrogen atoms of the tetrazole ligand are oriented towards the metal at distances of 2.539(14) and 2.812(18) \rA. The Sm(ring) average (2.73(2) \rA) in {bd6} is the same as that in {bd5} and the SmI distance is larger (3.100(2) vs 3.048(2) \rA).

Synthesis and X-ray crystal structure of a heterobimetallic bridged alkynide complex (C5Me5)2Y(μ-CCCMe3)2Li(THF)

Abstract YCl3 reacts with four equivalents of t-C4H9Li to form Y(CMe3)4Li(THF)4 (1) in high yield. 1 reacts with HCCCMe3 to form Y(CCCMe3)4Li(THF) (2) quantitatively. 2 reacts with KC5Me5 to form (C5Me5)2Y(μ-CCCMe3)2Li(THF) (3) which can also be prepared from (C5Me5)2YCl(THF) and LiCCCMe3. 3 crystallizes from toluene at −34°C in space group Cmcm with a = 13.363(4) A, b = 15.918(7) A, c = 17.453(9) A and Dcalcd = 1.07 g cm−3 for Z = 4. Least-squares refinement of the model based on 733 reflections converged to a final RF = 0.077. 3 contains a (C5Me5)2Y bent metallocene unit connected to Li via two alkynide bridges. The proximity of the two CMe3 groups to Li prevents coordination by more than one THF of solvation.

Additions and Corrections: Facile Stereospecific Synthesis of a Dihydroxyindenoindene Unit from an Alkyne and CO via Samarium-Mediated CO and CH Activation.

Nucleophilic Activation of Coordinated Carbon Monoxide. 3. Hydroxide and Methoxide Reactions with the Trinuclear Clusters MJ(C0)12 ( M = Fe, Ru or Os). Implications with Regard to Catalysis of the Water Cas Shift Reaction [J. Am. Chem. SOC. 1985, 107, 585-5933. DAVID C. GROSS and PETER C. FORD* Page 592: The two equations appearing in the right-side column of print are incorrect. These should be respectively