Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. IV. Some Complexes of Group 2 Halides With Ethane-1,2-diamine

1996 ◽  
Vol 49 (1) ◽  
pp. 61 ◽  
Author(s):  
AF Waters ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Metal Salts ◽  
Nitrogen Base ◽  
X Ray ◽  
Structure Determinations ◽  
Group 2

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for a number of adducts of ethane-1,2-diamine (en) with Group 2 metal salts, MX2.n(en). [Mg(en)3] Br2.MeOH (1) is monoclinic, P 21/c, a 9.067(5), b 15.161(4), c 14.839(8) Ǻ, β 121.86(5)°, Z = 4 f.u .; R was 0.070 for No 1226 independent 'observed' (I > 3σ(I)) diffractometer reflections; [Mg(en)3] I2.MeOH (2) is triclinic, Pī , a 11.500(2), b 9.527(6), c 8.825(4) Ǻ, α 106.30(4), β 100.57(3), γ 90.28(4)°, Z = 2 f.u .; R 0.045 for No 3562. In (1) and (2), (Mg-N) are 2.20 and 2.19 Ǻ. [Ca(en)4]Br2 (3) is orthorhombic, Fddd , a 28.54(1), b 15.863(7), c 8.927(9) Ǻ, Z = 8 f.u .; Ca-N are 2.608(7) and 2.556(8) Ǻ. [ Sr (en)4] Cl2.2MeOH (4) is also orthorhombic, Fddd , a 26.627(8), b 15.388(4), c 11.313(4) Ǻ, Z = 8 f.u .; R 0.059 for No 535. [ Sr (en)4] Br2.2en (5) is tetragonal, I 41/a, a 9.215(7), c 27.678(3) Ǻ, Z = 4 f.u ., R 0.044 for No 657. [ Sr (en)4]I2.MeOH (6) is tetragonal, I41/amd, a 9.389(1), c 28.78(1) Ǻ, Z = 4. f.u ., R 0.040 for No 10. In (4), (5) and (6), Sr -N are 2.728(7), 2.718(7); 2.720(7), 2.703(7) and 2.75(2), 2.72(7) Ǻ. [ ClBa (en)3(en)(2/2)](∞ ׀ ∞) Cl (≡ BaCl2.4en) (7) is monoclinic, P 21, a 8.666(3), b 9.063(10), c 12.655(5) Ǻ, β 108.13(3)°, Z = 2 f.u ., R 0.048 for No 1479. In (1) and (2), magnesium is six-coordinate [Mg(N,N'- bidentate )3]; (3)-(6), calcium and strontium are eight-coordinate [M(N,N'- bidentate )4]; in (7), barium is nine-coordinate, one of the en ligands being bridging so that the complex is a single-stranded polymer generated by the 21 screw. Ba-Cl is 3.419(5) Ǻ, Ba -N bidentate en-N are 2.91(2)-2.97(3) Ǻ, and Ba -N monodentate en-N 2.92(1), 3.15(1) Ǻ.

Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. VI. Mixed Oligodentate-Aliphatic-Base/Oxygen Ligand Adducts

1996 ◽  
Vol 49 (1) ◽  
pp. 87 ◽  
Author(s):  
AF Waters ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Mixed Ligand ◽  
Metal Salts ◽  
Precise Description ◽  
Nitrogen Base ◽  
X Ray ◽  
Oxygen Ligand ◽  
Group 2 ◽  
Ligand Species

In the course of synthesizing oligodentate aliphatic nitrogen base adducts of Group 2 metal salts, a number of mixed- ligand species have been isolated with oxygen ligands , and characterized by room-temperature single-crystal X-ray studies. BaCl2.4en.H2O ≡[(en)4Ba(OH2)] Cl2 (1) is monoclinic, P 21/c, a 9.456(4), b 14.953(6), c 14.82(1) Ǻ, β 100.78(6)°, Z = 4 f.u ., R 0.043 for No 1862 independent 'observed' (I > 3σ(I)) diffractometer reflections. Ba -N range between 2.900(9) and 2.97(1) Ǻ, and Ba-O is 2.779(8) Ǻ in the nine-coordinate BaN8O environment. CaCl2.2dien.H2O ≡ [( dien )2Ca(OH2) Cl ] Cl (2) is monoclinic, P 21/c, a 10.808(4), b 11.999(4), c 15.71(1) Ǻ, β 123.58(4)°, Z = 4 f.u ., R 0.050 for No 3134; CaBr2.2dien.2H2O ≡ [( dien )2Ca(OH2)2] Br2 (3) is monoclinic, P 21/c, a 18.001(3), b 11.983(6), c 21.562(5) Ǻ, β 124.97(2)°, Z = 8 f.u ., R 0.045 for No 2858; CaBr2.2dien.2MeOH ≡ [( dien )2Ca( HOMe )2] Br2 (4) is orthorhombic, P212121, a 16.620(8), b 12.78(1), c 9.765(4) Ǻ, Z = 4 f.u ., R 0.073 for No 878. In (2)-(4), the cation configurations are similar, being of the form [L2Ca( dien )2], L (L') being the unidentate ligand, with the eight-coordinate calcium environments [L2Ca(N3)2] in a common isomeric configuration, the two ligands L being cis in an array of quasi-2 symmetry. Ca- Cl in (2) is 2.834(1) Ǻ; Ca-N generally range between 2.52(5) and 2.64(1) Ǻ; Ca-O(H2O) is 2.418(2) in (2), 2.434(7)-2.496(7) Ǻ in (3), while Ca-O( MeOH ) in (4) are 2.43(2) and 2.43(2) Ǻ. [Mg(HOMe)6] I2.2tmeda (5) ( tmeda = Me2N(CH2)2NMe2), orthorhombic, Pbca, a 23.423(8), b 15.306(4), c 9.345(1) Ǻ, Z = 4 f.u ., R 0.052 for No 1928, provides a usefully precise description for the centrosymmetric cation, Mg-O being 2.069(4), 2.080(4), 2.096(5) Ǻ, with Mg-O-C 128.4(4) l28.9(4), l29.7(4)°. [( tmeda )SrI2 ( HOMe )3].½tmeda (6), monoclinic, P 21/c, a 7.730(1), b 35.493(9), c 11.081(2) Ǻ, β 126.49(1)°, R 0.042 for No 3161, has a seven-coordinate, quasi-pentagonal bipyramidal SrN2I2O3 array about the metal with trans-iodines.

Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. IX. Some Complexes of Group 2 Metal Halides With 2,2':6',2"-Terpyridine

1996 ◽  
Vol 49 (1) ◽  
pp. 137 ◽  
Author(s):  
BW Skelton ◽  
AF Waters ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Nitrogen Base ◽  
Space Group ◽  
Trigonal Symmetry ◽  
X Ray ◽  
Space Groups ◽  
Structure Determinations ◽  
Group 2 ◽  
A Site

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for a number of adducts of MX2.ntpy stoichiometry of salts of Group 2 metals, MX2, with 2,2':6',2"-terpyridine ( tpy ). ' Homoleptic' adducts, [M( tpy )3] X2, are found in space groups with trigonal symmetry, with M located on a site of at least 3 symmetry, the structures being derivative of the P 62c array found in [ Pb ( tpy )3] (ClO4)2, but with variations in anion and cation stackings . [M( tpy )3] I2.~1.7MeOH, M = Ca (1), Sr (2), are trigonal , P3c1, a ≈ 13, c ≈ 15.3 Ǻ, Z = 2 f.u., conventional R on ׀ F ׀ being 0.050, 0.086 for No 894, 865 independent 'observed' (I > 3σ(I)) reflections respectively. [ Sr ( tpy )3] Br2.2MeOH (3), although similar, is modelled in space group P3c1, a 13.040(4), c 15.13(1) Ǻ, Z = 2 f.u ., R 0.041 for No 447. [( tpy )2BaI2] (4) is monoclinic, P 21/c, a 10.812(4), b 16.740(5), c 17.458(4) Ǻ, β 109.39(2)°, Z = 4 f.u ., R 0.042 for No 3256. [( tpy )2Ba(O2ClO2)2] (5) is triclinic, Pī , a 14.220(4), b 11.212(2), c 10.511(2) Ǻ, α 65.66(2), β 87.32(2), γ 88.92(2)°, Z = 2 f.u ., R 0.029 for No 4676.

Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. V. Some Complexes With 3-Azapentane-1,5-diamine

1996 ◽  
Vol 49 (1) ◽  
pp. 73 ◽  
Author(s):  
AF Waters ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Tridentate Ligands ◽  
Nitrogen Base ◽  
Space Group ◽  
X Ray ◽  
Group 2 ◽  
Probable Space ◽  
Structural Characterizations

Syntheses and room-temperature single-crystal X-ray structural characterizations are recorded for an array of adducts of H2N(CN2)2NH(CH2)2NH2, ' dien ', with salts of Group 2 elements, MX2.n( dien ).[Mg( dien )2] Cl2 (1) is monoclinic, P 21/c, a 11.326(6), b 10.928(5), c 12.636(6) Ǻ, β 92.74(4)°, Z = 4 f.u .; R was 0.047 for No 1726 independent 'observed' (I > 3σ(I)) diffractometer reflections. [Mg( dien )2] Br2 (2) is monoclinic, P 21/c, a 9.541(7), b 14.55(1), c 11.894(8) Ǻ, β 100.42(5)°, Z = 4 f.u ., R 0.054 for No 1778. [Mg( dien )2] I2 (3) is isomorphous , a 9.969(2), b 14.907(2), c 12.300(3) Ǻ, β 100.02(2)°, R 0.039 for No 3180. In all three complexes, the two tridentate ligands are disposed mer in a six-coordinate MgN6 environment, the trans Mg-N(central) distances being somewhat shorter (2.161 (4)-2.181(9)Ǻ) than Mg-N(distal) (2.215(8)-2.249(4)Ǻ). [Ba(dien)3] Cl2 (4a) is orthorhombic, Pnaa , a 19.309(2), b 13.545(2), c 8.872(2)Ǻ, Z = 4 f.u ., R 0.055 for No 1070; the methanol disolvate (4b) is monoclinic, P 21/c, a 16.807(8), b 8.764(5), c 19.493(4) Ǻ, β 102.39(3)°, Z = 4 f.u ., R 0.11 for No 2613. A family of derivative structures (5)-(8), [M( dien )3] X2, M, X = Sr , Br (5), Sr , I(6), Ba , Br (7), Ba , I(8), have cells of half the volume (a ≈ 13.8, b ≈ 9, c ≈ 9.8 Ǻ), probable space group P21212, R 0.050, 0.061, 0.034, 0.037 for No 549, 914, 1044, 1801 respectively, with the cations disposed about crystallographic 2 axes with one disordered ligand . [ Ba( dien )3](ClO4)2 (9) is rhombohedral , R3c, a 10.240(2), c 45.19(1) Ǻ (hexagonal setting), Z = 6 f.u ., R 0.054 for No 508. Like (4)-(8), the barium environment is nine-coordinate with the three tridentate ligands here� disposed about a 3 axis through the metal.

Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. I. Some Adducts of Group 2 Halides With Acetonitrile

1996 ◽  
Vol 49 (1) ◽  
pp. 27 ◽  
Author(s):  
AF Waters ◽  
AH White
Keyword(s):  
Coordination Sphere ◽  
Molecular Species ◽  
Room Temperature ◽  
Linear Array ◽  
Nitrogen Base ◽  
X Ray ◽  
Unusual Combination ◽  
Anionic Species ◽  
Group 2 ◽  
O 352

Recrystallization of anhydrous Group 2 halides from anhydrous acetonitrile has yielded, in a number of cases, adducts MX2.nMeCN suitable for characterization by room-temperature single-crystal X-ray studies, which revealed novel stereochemical types. Magnesium(II) bromide yields a trisolvate, ionic with disproportionated ligand arrays, as [Mg(NCMe)6][MgBr4] (1), an unusual combination of homoleptic cationic and anionic species. Crystals are triclinic, Pī , a 19.129(1), b l6.870(8), c 8.737(7) Ǻ,α 83.96(3), β 87.93(4), γ 65.24(2)�, Z=4 f.u .; R was 0.068 for N o 3181 'observed' (I > 3σ(I)) reflections. Mg-N are 2.12(2)-2.18(2) Ǻ, and Mg-Br are 2.452(7)-2.481(6) Ǻ. Calcium(II) bromide, by contrast, yields a disolvate , an infinite polymer, with the two MeCN ligands trans in a quasi-octahedral coordination sphere, and the polymer comprising a ... Ca(μ-Br)2Ca(μ-Br)2... linear array. Crystals of 1:2 CaBr2/MeCN (2) are orthorhombic, Pbam , a l4.252(3), b 8.539(2), c 4.2088(6) Ǻ, Z=2 f.u .; R 0.043 for N o 352. Ca-N is 2.46(1) Ǻ, and Ca-Br 2.8765(9) Ǻ. CaI2 and SrI2 yield pentasolvates as neutral, molecular species [( MeCN )5MX2] (3) and (4), with the halides trans in a pentagonal bipyramidal coordination sphere. They are isomorphous . orthorhombic, Pcab , a ≈ 18.4, b ≈ 14.6, c ≈ 14.3 Ǻ, Z = 8 f.u .; R were 0.042 and 0.059 for N o 2297 and 1489 respectively. Ca-I are 3.132(2), 3.116(2) Ǻ and Sr -I are 3.265(3), 3.238(3) Ǻ, while Ca-N are (range) 2.518(8)-2.566(8) Ǻ and Sr -N 2.68(2)-2.73(2) Ǻ.

Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. VII. Some Complexes of Group 2 Metal Halides With Aromatic N,N'-Bidentate Ligands

1996 ◽  
Vol 49 (1) ◽  
pp. 99 ◽  
Author(s):  
BW Skelton ◽  
AF Waters ◽  
AH White
Keyword(s):  
Room Temperature ◽  
The Novel ◽  
Bidentate Ligands ◽  
Nitrogen Base ◽  
One Dimensional ◽  
X Ray ◽  
L System ◽  
L Systems ◽  
Group 2 ◽  
Structural Characterizations

Syntheses and room-temperature single-crystal X-ray structural characterizations are recorded for a number of adducts of Group 2 halides with the aromatic N,N′- bidentate ligands L = 2,2'-bipyridine ( bpy ) and 1,10-phenanthroline ( phen ). One adduct of 1 : 1 MX2/L stoichiometry is recorded: [( bpy )Ca(μ-Br)(4/2)](∞ ׀ ∞) (1) is monoclinic, C 2/c, a l7.102(5), b 9.845(1), c 7.600(2) Ǻ, β 107.65(2)°, Z = 4 f.u .; conventional R on #1472; F ׀ at convergence was 0.057 for No 817 independent 'observed' ( I > 3σ(I)) reflections, the compound being a one-dimensional polymer… CaL (μ-Br)2CaL(μ-Br)2…, with six-coordinate calcium, cis-CaN2(μ-Br)4, on a twofold axis. 1 : 2 MX2/L systems have been described for two types of array: [( bpy )2CaI2] (2), orthorhombic, Pnca, a 16.914(4), b 13.80(1), c 9.290(4) Ǻ, Z = 4 f.u .; R 0.039 for No 1738, is discrete mononuclear, containing cis-CaN4I2 six-coordinate calcium, whereas the barium analogue is an infinite one-dimensional polymer, [( bpy )2Ba(μ-I)(4/2)](∞׀ ∞) (3), triclinic, Pī, a 11.318(2), b 11.078(2), c 9.206(4) Ǻ, α 80.87(2), β 77.52(2), γ 87.53(1)°, Z = 2 f.u .; R 0.032 for No 4154, with eight-coordinate (N2)2Ba(μ-I)4. The perchlorate analogue, [( bpy )2Ba(μ-OClO2O)(4/2)](∞ ׀ ∞) (4), although of similar stoichiometry, has a trans-rather than a cis-linked chain; it is monoclinic, P 21/c, a 6.606(2), b 18.661(7), c 19.440(8) Ǻ, β 109.45(4)°, Z = 4 f.u .; R 0.044 for No 4060, with μ-I replaced by O,O'-ClO4 bridging units and eight-coordinate barium, (N2)2BaO4. The 1 : 3 MX2/L system is represented (as its hemi( bipyridine ) 'solvate') by mononuclear [( bpy )3SrI2].0.5bpy (5), monoclinic, P 21/c, a 20.834(8), b 9.735(4), c 18.460(7) Ǻ, β 114.87(3)°, Z = 4 f.u .; R 0.039 for No 3711, containing eight-coordinate strontium, [(N2)3SrI2]; there is also an isomorphous calcium/ perchlorate analogue [( bpy )3Ca(OClO3)2].0.5bpy (6), a 21.413(6), b 9.813(4), c 18.659(2) Ǻ, β 115.67(2)°, R 0.057 for No 3090, in which unidentate O-ClO4 ligands replace the iodine about the metal atom. A 1 : 4 adduct is obtained with CaI2/phen; ionic [Ca( phen )4] I2 (7), triclinic, Pī , a 14.703(3), b 13.292(3), c 11.38(1) Ǻ, α 92.78(4), β 96.15(4), γ 105.22(2)°, Z = 2 f.u ., R 0.053 for No 3658, contains eight-coordinate Ca(N2)4 arrays, while the novel 1 : 5 adduct [ Ba ( phen )4] I2.MeCN (8) is triclinic, Pī , a 12.170(6), b 13.760(7), c 18 254(8) Ǻ, α 77.05(9), ,β 71.96(4), γ 70.83(9)°, Z = 2 f.u ., R 0.040 for No 4447, containing 10-coordinate barium, [ Ba (N2)5]. A 1 : 4 adduct formed with BaBr2 is [ BrBa( phen )4] Br.MeOH (9), triclinic, Pī , a 17.748(4), b 17.418(2), c 15.535(7) Ǻ, α 91.63(2), β 100.53(3), γ 115.39(1)°, Z = 4 f.u ., R 0.062 for No 4092, containing nine-coordinate barium, [ BrBa (N2)4].

Structural Systematics of 2/4-Nitrophenoxide Complexes of Closed-Shell Metal Ions. VII Acid Salts of the 4-Nitrophenoxides of Group 2

1998 ◽  
Vol 51 (8) ◽  
pp. 785 ◽  
Author(s):  
Jack M. Harrowfield ◽  
Raj Pal Sharma ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Room Temperature ◽  
Calcium Salt ◽  
Three Dimensional ◽  
Closed Shell ◽  
The Other ◽  
X Ray ◽  
C 23 ◽  
Structure Determinations ◽  
Group 2 ◽  
Acid Salts

Room-temperature single-crystal X-ray structure determinations are recorded for a number of Group 2 4-nitrophenoxide acid salts, variously hydrated M(4-np)2.x(4-npH).yH2O. Ca(4-np)2.2(4-npH).8H2O is monoclinic, P 21/n, a 30·52(1), b 10·027(1), c 23·65(2) Å, β 116·3(5)°, Z = 8, conventional R on |F| being 0·058 for No 5092 independent ‘observed’ (I > 3s(I)) reflections. Sr(4-np)2.2(4-npH).8H2O, based on a subcell of the former, is monoclinic, P 21/c, a 15·576(5), b10·081(6), c 24·20(2) Å, β 117·99(5)° , Z = 4, R 0·054 for No 2908. Ba(4-np)2.2(4-npH).4H2O is orthorhombic, Fdd2, a 28·01(1), b 19·90(1), c 10·692(7)Å, Z = 8, R 0·028 for No 1967. The strontium array (and that of the calcium salt developed from it) may be represented as [(H2O)6Sr(4-npH.4-np)] (4-npH.4-np), a neutral ligand being unsymmetrically chelated to the strontium through the nitro group, with a quasi-parallel counter ion hydrogen-bonded to it by phenoxide confrontation. The other two 4-np residues make up a similar phenoxide-confronting pair (4-npH.4-np), the hydrogen being more intimately associated with one moiety. The barium salt is also an interesting array: the 10-coordinate barium lies on a crystallographic 2 axis, in an environment of two pairs of symmetry-related nitro-chelating ligand anions, and a pair of nitro-O coordinating neutral 4-npH ligands; the whole [(H2O)4Ba(4-np)2(4-npH)2] array may be envisaged as a single neutral (super)molecule. Hydrogen bonds between confronting phenoxides of the neutral 4-npH components of the parent and the 4-np- components of neighbouring molecules link the whole into a three-dimensional array.

Structural Systematics of 2/4-Nitrophenoxide Complexes of Closed-Shell Metal Ions. V 2-Nitrophenoxides of Group 2

1998 ◽  
Vol 51 (8) ◽  
pp. 761 ◽  
Author(s):  
Jack M. Harrowfield ◽  
Raj Pal Sharma ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Water Molecule ◽  
Metal Ions ◽  
Single Crystal ◽  
Room Temperature ◽  
Closed Shell ◽  
Magnesium Salt ◽  
Water Molecules ◽  
One Dimensional ◽  
X Ray ◽  
Group 2

Room-temperature single-crystal X-ray studies are recorded for 2-nitrophenoxide salts of Group 2 metals, variously hydrated M(2-np)2.xH2O, M = Mg, Ca, Sr; the structure of the barium analogue has been previously recorded. Mg(2-np)2.2H2O is monoclinic, P21/a, a 7·377(1), b 7·518(1), c 12·877(3) Å, β 106·58(2)°, Z = 2; conventional R on |F| 0·13 for No 508 independent ‘observed’ (I > 3σ(I)) reflections. Ca(2-np)2.H2O is monoclinic, C2, a 25·92(1), b 7·176(3), c 3·660(4) Å, β 93·66(5)°, Z = 2, R 0·061 for No 541. M(2-np)2.4H2O, M = Ca, Sr, are isomorphous, monoclinic, C2/c, a ≈ 31·3, b ≈ 8·1, c ≈ 12·8 Å, β 103°, Z = 8; R was 0·056, 0·055 forNo 1988, 1744 respectively. The magnesium salt is a discrete molecular array disposed about a crystallographic inversion centre with chelating phenoxide ligands: trans-[Mg(2-np)2(OH2)2]. The calcium monohydrate salt is a novel one-dimensional polymer with a ... Ca(µ-O)2Ca(µ-O)2Ca ... spine, the ligand pairs chelating the calcium with phenoxide-O additionally bridging. The seven-coordinate calcium atoms lie on the crystallographic 2 axis with the water molecule, also on that axis, making up a seven-coordinate environment. The tetrahydrate is also a one-dimensional polymer with a similar spine, the bridging oxygen atoms derivative of water molecules. A chelating ligand and two further water molecules make up an eight-coordinate metal environment, with the free anions interleaving stacks of coordinated anions up c.

Lewis-Base Adducts of Lead(II) Compounds. XVII. Synthetic and Structural Studies of Some 1:1 Adducts of 2,2':6,2'-Terpyridine With Lead(II) Salts

1996 ◽  
Vol 49 (10) ◽  
pp. 1135 ◽  
Author(s):  
LM Engelhardt ◽  
JM Harrowfield ◽  
H Miyamae ◽  
JM Patrick ◽  
BW Skelton ◽  
...  
Keyword(s):  
Water Molecule ◽  
Single Crystal ◽  
Room Temperature ◽  
Lewis Base ◽  
Polymeric Chain ◽  
Lead Atom ◽  
X Ray ◽  
Structure Determinations ◽  
Pass Through ◽  
Nitrate And Nitrite

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for 1:1 adducts of 2,2':6',2"-terpyridine (' tpy ') with the lead(II) oxoanion salts perchlorate, nitrate and nitrite, ( tpy ) Pb ( oxoanion )2. All structures are monoclinic, C2/c, Z = 4, with approximate ranges a from 9 to 11 Ǻ, b from 16 to 20 Ǻ, c from 9.8 to 13.8 Ǻ, β from 113 to 130° and V from 1650 to 1850 Ǻ3. In all cases the lead(II) atoms are disposed on crystallographic 2 axes which also pass through the axis of the central tpy ring; a pair of symmetry related oxoanions link successive lead atoms in a one-dimensional polymeric chain parallel to the ac cell diagonal, one pair of oxygen atoms functioning as an O,O'-bidentate with another oxygen (replaced by the nitrogen in the nitrite) bridging to the adjacent lead atom; the third anionic oxygen atom in the nitrate is replaced by a water molecule in the nitrite, which thus becomes a monohydrate. Residuals were 0.030, 0.034 and 0.040 for 2122, 1564 and 2059 independent 'observed' (I > 3σ(I)) reflections respectively. Also recorded are the syntheses and room-temperature single-crystal X-ray structure determinations for 1:1 aducts of 2,2':6',2"-terpyridine with lead(II) chloride, bromide and iodide, the chloride and bromide being hydrated. ( tpy )PbCl2.H2O is monoclinic, P 21/c, a 8.938(1), b 15,210(7), c 13.414(3) Ǻ, β 115.17(1)°, Z = 4 f.u .; R was 0.036 for No = 3346 independent, 'observed' reflections. The complex is centrosymmetric, binuclear [( tpy ) (H2O)( Cl ) Pb (μ- Cl )2Pb( Cl )(OH2)( tpy )], with the two lead atoms linked by bridging chlorine atoms; the lead atoms are seven-coordinate N3,O,ClPb(μ- Cl )2. The bromide ( tpy )PbBr2.2/3H2O, triclinic, Pī, a 12.360(6), b 12.452(4), c 18.372(6) Ǻ, α 108.31(3), β 109.44(3), γ 90.56(3)°, Z = 6 f.u ., R being 0.046 for No 7282, is in fact trinuclear [Pb3Br6( tpy )6].2H2O, a novel and elegant oligomer with quasi-2 symmetry in which a central lead atom (on the quasi-2 axis) is seven-coordinated [( tpy ) Pb (μ-Br)4] with the associated bromides bridging to a pair of peripheral lead atoms, also seven coordinated, [( tpy )(Br) Pb (μ-Br)3]. Unsolvated ( tpy )PbI2, triclinic, Pī , a 10.834(3), b 9.023(3), c 8.906(2) Ǻ, α 80.34(2), β 89.40(2), γ 79.78(2)°, Z = 2 f.u ., R 0.031 for No 2347 is, like the chloride, centrosymmetric binuclear, [( tpy )(I) Pb (μ-I)2Pb(I)( tpy )], but with the lead(II) now six-coordinate N3(I) Pb (μ-I)2. In both chloride and iodide, the tpy plane is approximately normal to the Pb ... Pb line with the water molecule of the chloride approximately trans to the central tpy nitrogen; in the iodide that site is occupied by the terminal halide.

Structural Systematics of Rare Earth Complexes. XXII. ('Maximally') Hydrated Rare Earth Iodides

2000 ◽  
Vol 53 (10) ◽  
pp. 867 ◽  
Author(s):  
Kevin C. Lim ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Aqueous Solution ◽  
Rare Earth ◽  
Low Temperature ◽  
Single Crystal ◽  
Room Temperature ◽  
Second Phase ◽  
X Ray ◽  
Structure Determinations ◽  
Trivalent Rare Earth ◽  
Trigonal Prismatic

Low-temperature (c. 153 K) single-crystal X-ray structure determinations, carried out on trivalent rare earth iodides crystallized from aqueous solution at room temperature, have defined two series of hydrates, LnI3.nH2O. For Ln = La–Ho, a nonahydrate phase (n = 9) is defined, orthorhombic Pmmn, a ~ 11.5, b ~ 8.0, c ~ 8.8 Å, Z = 2, the second phase (n = 10), monoclinic P21/c, Z = 4 being defined for Ln = Er–Lu, a ~ 8.2, b ~ 12.8, c ~ 17.1 Å, β ~ 103.7˚. Neither of these phases is isomorphous with any of those pertinent to the previously studied chloride or bromide (hydrated) arrays, nor, unlike those, does the halide (iodide) in any case enter the coordination sphere of the lanthanoid. The n = 9 phase takes the form [Ln(OH2)9]I3, the nine-coordinate lanthanoid environment stereochemistry being tricapped trigonal-prismatic, while the n = 10 phase is [Ln(OH2)8]I3.2H2O, the eight-coordinate lanthanoid environment being square-antiprismatic.

α-Sulfonyl Radical Initiated Intramolecular Tandem Radical Cyclization: Stereochemistries of a Pair of Doubly Cyclized Products

2003 ◽  
Vol 56 (7) ◽  
pp. 715 ◽  
Author(s):  
Lindsay T. Byrne ◽  
Manat Phomakotr ◽  
Chompoonut Poolsanong ◽  
Vichai Reutrakul ◽  
Brian W. Skelton ◽  
...  
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Radical Cyclization ◽  
X Ray ◽  
Structure Determinations

Room-temperature single-crystal X-ray structure determinations are recorded for trans-1,2,3,3a,9,9a-Hexahydro-cyclopenta[b]-1-benzothiapyran-4,4-dioxide and its 3a-methyl analogue, minor products of the α-sulfonyl radical-initiated intramolecular tandem radical cyclization of H2C=CH(CH2)CRBrSO2Ph (R = H, CH3), confirming the assigned structures and rigorously establishing the trans relationship at the ring junctions.

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