Andrew N. Rollins

Synthetic and structural studies on new vinylcyclopentadienyl derivatives of titanium, iron and thallium

Abstract An improved procedure for the preparation of vinylcyclopentadienyllithium (1) from 6-methylfulvene and lithium diisopropylamide in THF solution has been developed. Reaction of 1 with thallium ethoxide in THF has produced vinylcyclopentadienylthallium (3). Compounds 1 and 3 have been used in the synthesis of vinyl- (4) and 1,1′-divinyltitanocene dichloride (5). Treatment of 1,2,3,4,6-pentamethylfulvene with lithium diisopropylamide in THF solution has afforded vinyltetramethylcyclopentadienyllithium (2) in high yield. Reactions of 2 with FeCl2 or TiCl4 have led to bis(η5-vinyltetramethylcyclopentadienyl)iron (7) and (η5-vinyltetramethylcyclopentadienyl)titanium trichloride (8), respectively. Compound 8 reacts with (η5-C5H5)T1 to produce 1-vinyl-2,3,4,5-tetramethyltitanocene dichloride (9) in high yield. The crystal structure of 5 has been determined. 5 is monoclinic, C21/c, with a = 14.420(3), b = 6.610(2), c = 14.111(3) A, β = 102.18(2)° and Dcalc = 1.52 g cm−3 for Z = 4. The Ti atom resides on a crystallographic two-fold axis. The η5-vinylcyclopentadienyl groups are slightly staggered with the carbons bonded to the vinyl groups next to one another and between the ClTiCl bond. The TiC(η5) separations range from 2.343(4) to 2.450(3) A, the latter values for the carbon atoms bonded to the vinyl group.

Primary to secondary sphere coordination of 18-crown-6 to lanthanide (III) nitrates: Structural analysis of [Pr(NO3)3-(18-crown-6)] and [M(NO3)3(OH2)3]·18-crown-6 (M=Y, Eu, Tb−Lu)

The direct reaction of hydrated lanthanide nitrate salts with 18-crown-6 in 3∶1 CH3CN∶CH3OH has resulted in the isolation and structural characterization of [Pr(NO3)3(18-crown-6)] and [M(NO3)3(OH2)3]·18-crown-6 (M=Y, Eu, Tb−Lu). (The Eu and Yb analogs were confirmed with preliminary cell data only.) [Pr(NO3)3(18-crown-6)] is 12-coordinate icosahedral and crystallizes in the orthorhombic space group Pbca with (at 20°C)a=12.230(2),b=15.598(4),c=21.777(9)Å andDcalc=1.89 g cm−3 forZ=8. The seven isostructural [Pr(NO3)3(18-crown-6)] complexes all contain 9-coordinate capped square antiprismatic metal centers hydrogen bonded via the bound water molecules to D3d 18-crown-6 within the lattice to form hydrogen bonded polymeric chains. Each complex is orthorhombic Pnma with cell parameters as follows: M=Tb (20°C):a=15.242(6),b=14.253(11),c=11.070(6)Å,Dcalc=1.83 g cm−3 forZ=4; M=Dy (20°C):a=15.248(3),b=14.239(5),c=11.058(3)Å,Dcalc=1.84 g cm−3 forZ=4; M=Y (19°C):a=15.260(2),b=14.238(2),c=11.048(3) Å,Dcalc=1.64 g cm−3 for Z=4; M=Ho (20°C):a=15.226(4),b=14.208(15),c=11.028(3)Å,Dcalc=1.86 g cm−3 forZ=4; M=Er (20°C):a=15.250(3),b=14.208(7),c=11.028(3)Å,Dcalc=1.87 g cm−3 forZ=4; M=Tm (20°C):a=15.246(6),b=14.190(16),c=11.013(6) Å,Dcalc=1.88 g cm−3 forZ=4; M=Lu (21°C):a=15.244(9),b=14.158(6),c=10.980(7)Å,Dcalc=1.90 g cm−3 forZ=4.

Primary to secondary sphere coordination of 15-crown-5 to lanthanide(III) chlorides: structural analysis of [MCl3(15-crown-5)] (M=La, Ce) and [Er(OH2)8]Cl3·15-crown-5

Complexes of LaCl3·7H2O and CeCl3·7H2O directly coordinated to 15-crown-5 were prepared by placing the reactants in 3∶1 CH3CN∶CH3OH on opposite sides of a fine porosity glass frit in a U-shaped cell and passing a 10 μA current through the cell. The crystal structures of the two anhydrous 8-coordinate complexes, [MCl3(15-crown-5)] (M=La, Ce) have been determined. Each contains the lanthanide in a bicapped trigonal prismatic geometry. The two complexes are isostructural crystallizing in the monoclinic space groupP21/c with (at 20°C) for M=La:a=8.217(8),b=14.298(2),c=14.341(9) Å, β=104.79(8)°, andDcalc=1.90 g cm−3 forZ=4; for M=Ce:a=8.208(9),b=14.263(6),c=14.270(8) Å, β=104.74(7)°, andDcalc=1.92 g cm−3 forZ=4. Direct reaction of ErCl3·6H2O with 15-crown-5 in 3∶1 CH3CN∶CH3OH resulted in the crystallization of the second sphere hydrogen bonded complex [Er(OH2)8]Cl3·15-crown-5. This complex is monoclinic,P21/n with (at 18°C)a=9.193(3),b=17.235(9),c=15.216(5) Å, β=92.48(3)°, andDcalc=1.76 g cm−3 forZ=4. The Er3+ ion is dodecahedral.

Mixed anion lanthanide(III) crown ether complexes: crystal structures of [LaCl2(NO3)(12-crown-4)]2, [La(NO3)(OH2)4-(12-crown-4)]Cl2·CH3CN and [LaCl2(NO3)(18-crown-6)]

Reaction of LaCl3·7H2O containing small amounts of La(NO3)3·7H2O as an impurity with 12-crown-4 or 18-crown-6 in 3:1 CH3CN:CH3OH resulted in the isolation of the mixed anion complexes [LaCl2(NO3)(12-crown-4)]2, [La(NO3)(OH2)4(12-crown-4)]Cl2·CH3CN and [LaCl2(NO3)(18-crown-6)]. The nine-coordinate dimer, [LaCl2(NO3)(12-crown-4)]2, has all of the anions in the inner coordination sphere and La3+ has a capped square antiprismatic geometry. It crystallizes in the orthorhombic space group Pbca with (at −150 °C) a = 12.938(6), b = 15.704(3), c = 13.962(2) A, and Dcalc = 2.08 g cm−3 for Z = 4. The second complex isolated from the same reaction, [La(NO3)(OH2)4(12-crown-4)]Cl2·CH3CN, has the bidentate nitrate anion in the inner coordination sphere but the two chloride anions are in a hydrogen bonded outer sphere. This complex is ten-coordinate 4A,6B-expanded dodecahedral and crystallizes in the monoclinic space group P21 with (at 20 °C) a = 7.651(2), b = 11.704(7), c = 11.608(4) A, β = 95.11(2)°, and Dcalc = 1.80 g cm−3 for Z = 2. The 18-crown-6 complex, [LaCl2(NO3)(18-crown-6)], has all inner sphere anions and has ten-coordinate 4A,6B-expanded dodecahedral La3+ centers. It crystallizes in the orthorhombic space group Pbca with (at 20 °C) a = 14.122(7), b = 13.563(5), c = 19.311(9) A, and Dcalc = 1.89 g cm−3 for Z = 8.

Synthesis and Structural Characterization of the Monodentate 12-Crown-4 And Hexaethylene Glycol Complexes of Uranium(VI): [UO2Cl2(OH2)2(12-CROWN-4)].12-Crown-4 And UO2Cl2(OH2)2(Hexaethylene Glycol)

Abstract The reaction of anhydrous UO2Cl2 with 12-crown-4 or hexaethylene glycol (EO6) in THF with low water content resulted in the crystallization of [UO2Cl2(OH2)2(12-crown-4)]. 12-crown-4 and UO2Cl2(OH2)2(EO6). The crystal structures of both complexes were determined. Each complex consists of a uranyl ion coordinated to two chloride anions, two water molecules, and one oxygen of the polyether. Most of the uncoordinated ether oxygen atoms participate in hydrogen bonding. The hydrogen bonding in the 12-crown-4 complex produces a dimer, while the hydrogen bonding in the EO6 complex is polymeric. The etheric U-O separation of 2.546(4) A in the 12-crown-4 complex is the longest U-O contact in either complex, while the alcoholic U-O distance in the EO6 complex is a much shorter 2.433(5) A.

Macrocycle complexation chemistry 30: Comparison of the crystal structures of [La(NO3)3(15-crown-5)] and [La(NO3)3(monoaza-15-crown-5)]

Our group has been interested in the interaction of crown ethers with hydrated and anhydrous lanthanide salts for some time (Rogers and Nunez, 1990). Recently the structure of [La(NO3)3(monoaza-15-crown-5)] (Cragg et at., 1988) was published and found to be isostructural with the europium analog of the unsubstituted crown ether published by Bfinzli (1982, [Eu(NO3)3(15crown-5)]) rather than the unsubstituted [La(NO3)3(15crown-5)] (Pinzhe et al., 1983). In order to more accurately compare the effects of the mixed donor crown ether, we recently reprepared and structurally characterized [La(NO3)3(15-crown-5)]. This report will focus on the differences that may have resulted in these different crystalline environments.

Macrocycle complexation chemistry. 38. Crystallographic and ultraviolet/visible characterization of nitrobenzo-15-crown-5, dinitrobenzo-15-crown-5, and dinitrodibenzo-18-crown-6·2CH3CN

The crystal structures of three nitrated benzocrown ethers have been determined. Nitrobenzo-15-crown-5 crystallizes in the orthorhombic space group,Pca21, witha = 15.367(2),b = 4.8499(8),c = 19.963(5)Å, andDcalc = 1.40 g cm−3 forZ = 4. Dinitrobenzo-15-crown-5 crystallizes in the monoclinic space group,P21/n, witha = 11.716(2),b = 8.495(3),c = 17.441(5)Å,β = 108.40(2)° andDcalc = 1.44 g cm−3 forZ = 4.Dinitrodibenzo-18-crown-6·2CH3CN ismonoclinic,P21/n,witha = 8.138(2),b = 20.435(9),c = 15.953(9)Å,β = 100.55(4)° andDcalc = 1.36 g cm−3 forZ = 4. The nitro substituents are in the plane of the benzo ring except in the sterically congested dinitrobenzo-15crown-5. The observed crown ether conformations are similar to their substituted analogs.

f-Element/crown ether complexes. 27. The synthesis and crystal structure of [Ce(NO3)3 (OH2)(12-crown-4)] -12-crown-4

A unique cerium nitrate complex, [Ce(NO3)3(OH2)(12-crown-4)]-12-crown-4, has been crystallized from the reaction of hydrated cerium nitrate and 12-crown-4. It crystallizes in the orthorhombic space group,Pnma, with (at −150°C)a = 22.901(5),b = 13.547(3),c = 8.422(1)Å, andDx = 1.77 g cm−3 forZ = 4 formula units. A finalR value of 0.048 was obtained utilizing 2059 unique observed [Fo ⩾ 5σ(Fo)] reflections. The Ce atom resides on a crystallographic mirror plane and is 11-coordinate, coordinated to three bidentate nitrate groups, one water molecule and the four oxygens of one 12-crown-4 molecule. The water molecule hydrogen bonds a second 12-crown-4 unit. Both unique crown molecules and one of the nitrate anions are severely disordered.

The effects of methylene-substituents in crown ether backbones. Crystal structures of [Na(OH2)(methylene-16-crown-5)]I, [Na(NO2)(methylene-16-crown-5)]·0.5 (H2O), 3,16-dimethylene-26-crown-8,[Na4I4(3,16-dimethylene-26-crown-8)], and [Na2(OH2)4(3,16-dimethylene-26-crown-8)]I2

Abstract The crystal structures of five methylene substituted crown ether compounds were investigated. [Na(OH2)(methylene-16-crown-5)]I is orthorhombic, P212121 with a = 7.920(9), b = 10.787(3), c = 20.870(5)A, and Dcalc = 1.54 g cm−3 for Z = 4. The sodium cation is coordinated to all five etheric oxygen atoms and a water molecule giving it a coordination number of six. [Na(NO2)(methylene-16-crown-5)]·0.5(H2O) is monoclinic, P21/n with a = 20.566(6), b = 8.605(9), c = 20.821(7)A, β = 115.66(3)·, and Dcalc = 130 g cm−3 for Z = 8. Each sodium cation is seven-coordinate, coordinated to all five etheric oxygen atoms and a bidentate nitrite anion. One crown molecule is severely disordered. The macrocycles in both methylene-16-crown-5 structures have essentially the same conformations. 3,16-dimethylene-26-crown-8 is orthorhombic, Pccn with a = 18.061(4), b = 14.320(4), c = 8.659(7)A, and Dcalc = 1.20 g cm−3 for Z = 4. The crown ether has an elongated cavity generated by a series of six consecutive anti torsion ...

Comparison of the crystal structure and molecular models of N,N-diisobutyl-2-(octylphenylphosphinyl)acetamide (CMPO)

The crystal structure of N,N-diisobutyl-2-(octylphenylphosphinyl)acetamide, or CMPO was recently determined. The compound crystallizes in the space group P21/c witha=13.446(6),b=22.280(7),c=17.217(7) Å, β=92.07(4)°, andDcalc=1.05 g/cm3 forZ=8 @20°C). Molecular mechanics, molecular dynamics, and MNDO calculations were also performed on CMPO utilizing the SYBYL1 suite of programs. The results from these calculations are compared to the crystal structure and to similar calculations performed on CMPO using ALCHEMY2,3. In general, the results from the calculations agree fairly well with the parameters from the crystal structure.