Fernando Somoza

Coordination chemistry of transition metal complexes of a novel pentadentate ligand

Abstract The pentadentate ligand N-(2-pyridylmethyl)-3-(bis(2-pyridylmethyl)amine)-propanamide (LH) and transition metal complexes hereof were synthesised. The negative charge of the deprotonated ligand was meant to stabilise metal ions in high oxidation states thus facilitating aerobic oxidation of the metal centre. 1H NMR studies and X-ray crystallography showed that the Co(III)–OAc complex of LH (1) adopts the same structure in solution as in the crystalline state. Complex 1 crystallised in space group P21/c (no. 14). Furthermore, the 1H NMR studies revealed dynamic behaviour of the ligand backbone. The six-membered chelate ring undergoes inversion with an estimated activation energy of 14.6 kJ mol−1. The Fe(II) complex of LH was studied by 1H NMR in the presence CN− ions to force the iron complex into a low spin state. But the cyanide ions competed effectively with the amide portion of LH so the ligand only coordinated the Fe(II) ion with three of its five nitrogen atoms. Interestingly, two isomeric Fe(II) complexes formed; one with a meridonal arrangement of the three nitrogen atoms, the other having a facial arrangement. Upon standing the mer complex rearranged to the fac complex. As the complex mixture turned paramagnetic upon exposure to air, it seems that the ligand L− promote aerobic oxidation of Fe(II).

Reactions and Coordination Properties of the First Secondary Carbaboranyldiphosphane: 1,2-Bis(phenylphosphanyl)-1,2-dicarba-closo-dodecaborane(12)

When a mixture of stereoisomers of rac- and meso-1,2-bis(phenylphosphanyl)-1,2-dicarba-closo-dodecaborane(12) (1a, b; 1a/1b = 3:1) is treated with [Cp2ZrMe2] in boiling toluene for 2 h, the formation of three phosphorus-containing products, namely meso-[Cp2Zr(PPh)3] (3), (PPh)4 (4) and (PPh)5 (5), ratio 2.8:1.1:1.0, was observed by 31P-NMR spectroscopy. In the 11B-NMR spectrum of the reaction mixture, only signals for 1,2-dicarba-closo-dodecaborane(12) were observed. When zirconocene, prepared in situ from [Cp2ZrCl2] and BuLi, was treated with 1a, b at low temperature and then heated to reflux in toluene for 2 h, only formation of 3 and 1,2-dicarba-closo-dodecaborane(12) was observed. The mixture of stereoisomers of 1a, b reacts with CuCl in THF to give rac- and meso-[CuCl(THF){1,2-(PHPh)2C2B10H10}] (7a, b), which is only stable in THF solution and loses THF in vacuo over several hours to yield the insoluble colorless complex [CuCl{1,2-(PHPh)2C2B10H10}]n (8). In THF solution, 7 reacts with PPh3 to give the stable isolable complex [CuCl(PPh3){1,2-(PHPh)2C2B10H10}] (9). No reaction of 1a, b is observed with [Cp′Mo(CO)3]2 (Cp′ = C5H4Me) in boiling THF, while only decomposition occurs in boiling toluene. However, [(NBD)Mo(CO)4] (NBD = norbornadiene) reacts smoothly with 1a in toluene at room temperature to give cis-rac-[Mo(CO)4{1,2-(PHPh)2C2B10H10}] (10). Compounds 7, 9, and 10 were characterized spectroscopically (1H, 31P, 11B, 13C NMR, IR), and an X-ray structure determination was carried out on 10.

KRYPTORACEMIC CRYSTALLIZATION. PART 4. SYNTHESIS AND X-RAY STRUCTURE OF THE CONGLOMERATE [Co(en)2Ox]F 11.5H2O(I), ANOTHER EXAMPLE OF A COORDINATION COMPOUND CRYSTALLIZING AS A KRYPTORACEMATE

Abstract Aracemic solution of [Co(en)2Ox]F 11.5H2O(I), CoFO15.5N4C6H39, crystallizes as a kryptoracemate in the enantiomorphic space group C2 (No. 5) with lattice constants: a = 21.150(19) A, b= 11.866(8), c= 13.197(2) A and β = 101.62(8)°; V= 3243.97 A3 and d(calc; M.W. = 493.92 gm-mol−1, z = 8) = 2.020 g-cm3. A total of 2335 data were collected over the range of 4° ≤ 2θ ≤ 45°; of these, 1735 (independent and with I ≥ 2.5[sgrave](I)) were used in the structural analysis. Data were corrected for absorption (μ = 10.75 cm−1) and the relative transmission coefficients ranged from 0.5557 to 0.7852. Refinement converged to final residuals of 0.063 and 0.072 for R(F) and RW(F), respectively. There are two formula weights in the asymmetric unit of (I) and the absolute configuration was determined by the Flack test. For (I), the absolute configuration at Col is A(δλ.) and for Co2 is δ(λδ), which by comparision with the known absolute configurations of the chloride and bromide derivatives,4 allows us to assign the...

THE PHENOMENON OF CONGLOMERATE CRYSTALLIZATION. PART 48. TWO POLYMORPHS OF RACEMIC TRANS-[CO(2,3,2-TET) (NO2)2]NO3 (I AND II)

Abstract A racemic solution of trans-[Co(2,3,2-tet)(NO2)2]NO3(I), CoO7N7C7H20, crystallizes as a racemate in the centrosymmetric space group, P21/n with lattice constants: a=8.490(2)A, b=8.884(2), c=18.580(2) A and β=95.08(1)°; K=1395.89 A3 and d(calc; M.W.=373.21, Z=4)=1.776 g-cm−3. A total of 3489 data were collected over the range of 4° ≤ 2θ ≤ 55°; of these, 2684 (independent and with 1 ≥ 3s(I)) were used in the structural analysis. Data were corrected for absorption (μ=12.732 cm−1) and the relative transmission coefficients ranged from 0.7721 to 0.9980. Refinement converged to final residuals of 0.0465 and 0.0541 for R(F) and R w(F), respectively. The mother liquor of the same compound, prepared by a different route, produced a second crystalline form of trans-[Co(2,3,2-tet)(NO2)2]NO3(II), CoO7N7C7H20, which crystallizes in space group Pn with lattice constants: a=6.493(5)A, b=11.731(4), c=9.325(4) A and b=100.13(9)°; V=699.21 A3 and d(calc; M.W.=373.21, Z=2)=1.773 g-cm−3. A total of 2249 data were co...

The phenomenon of conglomerate crystallization Part 44. The crystallization behavior of [cis-Co(tren) (NO2)2]BF4(I), , the space group of and some bio-inorganic observations derived from their stereochemistry

Abstract [ cis -Co(tren) (NO 2 ) 2 ]BF 4 ( I ) (CoF 4 O 4 N 6 C 6 BH 18 ) crystallizes at 22°C, from a deionized water solution in space group Pnma (No. 62), with lattice constants: a = 12.052(3), b = 8.511(2), c = 13.242(3) A ; V = 1629.86 A 3 and D calc = 1.878 g cm −3 (MW = 383.98, Z = 4). A total of 4089 data was collected over the range 4 ≤ 2 θ ≤ 60°; of these, 2190 (independent and with I ≥ 2.5 σ ( I )) were used in the structural analysis. Data were corrected for absorption ( μ = 13.30 cm −1 ) and the transmission coefficients ranged from 0.5852 to 0.7439. The final R ( F ) and R w ( F ) residuals were 0.044 and 0.046, respectively. The cations exist in the lattice as enantiomeric pairs and the conformation of the three five-membered rings for the molecule described here are (N1ClC2N2 = 0°, on the mirror plane which disorders it), λ (N1C3C4N3 = −42.4°) and σ (N1C3′N3′ = +42.4°). [ cis -Co(tren) (NO 2 ) 2 ) 2 ] 2 SiF 6 ( II ) (Co 2 SiF 6 O 8 N 12 H 36 ) crystallizes as a conglomerate at 22°C, from a deionized water solution in space group P 4 3 2 1 2 with lattice constants: a = 11.180(4), c = 21.271(7) A ; V = 2658.58 A 3 and D calc = 1.840 g cm −3 (MW = 736.43, Z = 4). A total of 1695 data was collected over the range 4 ≤ 2 θ ≤ 50°; of these, 1197 (independent and with I ≥ 2.5 σ ( I )) were used in the structural analysis. Data were corrected for absorption ( μ = 13.90 cm −1 ) and the transmission coefficients ranged from 0.6093 to 0.7307. The final R ( F ) and R w ( F ) residuals were 0.042 and 0.045, respectively. The cations exist in the lattices as pure enantiomers and the conformation of the three five-membered rings of that dscribed here are λ (N1C1C2N2 = 29.4°), λ (N1C3C4N3 = −41.0°) and σ (N1C5C6N4 = + 42.0°). Crystals of the iodide, [ cis -Co (tren) (NO 2 ) 2 ]I ( III ), are disordered and appear to crystallize in the orthorhombic space groups Pbcm or Pbc 2 1 , with cell constants of a = 8.516(5), b = 15.081(4), c = 20.994(6) A , V = 2696.27 A 3 ; D calc = 2.207 g cm −3 (MW = 448.11, Z = 4). A total of 3166 data was collected over the range 4 ≤ 2 θ ≤ 55°; of these, 2154 (independent and with I ≥ 2.5 σ ( I )) were used in the structural analysis. Data were corrected for absorption ( μ = 35.50 cm −1 ) and the transmission coefficients ranged from 0.2812 to 0.4674. In both space groups we obtained a structural analysis implying severe disorder of the ligands surrounding the Co ion.

THE PHENOMENON OF CONGLOMERATE CRYSTALLIZATION. PART 47. COUNTERION CONTROL OF THE CRYSTALLIZATION PATHWAY. PART 8. THE CRYSTALLIZATION BEHAVIOR OF [trans-Co(3, 2, 3-tet)(NO2)2] CLO4 (I), trans-Co(3, 2, 3-tet)(NO2)2] BR · 3H2O (II) AND [trans-Co(3, 2, 3-tet)(NO2)2]I (III)

Abstract [trans-Co(3,2,3-tet)(NO2)2]ClO4 (I, CoClO8H6C8H22, crystallizes, at 22°C, from a deionized water solution in space group P21/n (a variant of No. 14), with lattice constants: a=10.782(3), b=9.198(3), c=17.031(5) A, β=105.30(2)°; V=1629.14 A3 and d(calc; MW=424.69, Z=4)=1.731 g-cm−3. A total of 3217 data were collected over the range of 4° ≤ 2θ ≤ 50°; of these, 2393 (independent and with I ≥ (2.5σ(I)) were used in the structural analysis. Data were corrected for absorption (μ=12.70 cm−1) and the transmission coefficients ranged from 0.9163 to 0.9965. The final R(F) and Rw(F) residuals were, respectively 0.043 and 0.045. The cations exist in the lattice as enantiomeric pairs and the conformation of the central, five-membered ring for the molecule described here is δ(N2-C4-C5-N3=+49.0°). The secondary nitrogens are both R(or S). The ClO4 − anion forms O…H bonds with a hydrogen of each of the two terminal -NH2 groups, thus rendering those hydrogens different and the terminal nitrogens chiral. In the c...

THE PHENOMENON OF CONGLOMERATE CRYSTALLIZATION. PART 49. THE CRYSTALLIZATION BEHAVIOR OF K[cis-β-(EDDA)(ox)l · H2O(I), AND OF [mer-Co(dien)(NH3(ox)]BR (II)

Abstract Racemic solutions of K[cis-β-(edda)(ox)]H2O (I) CoKO9N2C8H12, crystallize as racemic crystals, space group P21/c (No. 14) with cell constants of a = 8.993(4), 10.302(4), c = 14.590(9), (3=106.24(4)°, V= 1297.44 A3, d= 1.936 gm-cm3. (MW = 378.22 gm-mole−1; z = 4). A total of 3081 data were collected over the range of 4° ≤ 2θ ≤ 50° of these, 1695 (independent and with 1 ≥ 2.5[sgrave](I)) were used in the structural analysis. Data were corrected for absorption (μ = 16.861 cm−1) and the transmission coefficients ranged from 0.9163 to 0.9965. The final R(F) and Rw(F) residuals were, respectively 0.0299 and 0.0322. The anions exist in the lattice as enantiomeric pairs and the conformation of the central, five-membered ring for the molecule described here is δ(N1-C1-C2-N2 =+47.3°); that of the five-membered acetato ligands are, respectively, δ(+162.0°) and λ(-156.8°). The secondary nitrogens are both R. The potassium cation is bonded to the six oxygens. Racemic solutions of [mer-Co(dien)(NH3)(ox)]Br (II...

THE PHENOMENON OF CONGLOMERATE CRYSTALLIZATION. PART 42. THE CRYSTALLIZATION MODE AND CONFORMATIONAL AND CONFIGURATIONAL BEHAVIOR OF MER-TRINITRO COBALT TRIAMINES: [MER-Co(NH3)3(NO2)3] (I) AND [MER-Co(DPT)(NO2)3] (II)

Abstract The structure of the fac-[Co(NO2)3(NH3)3] isomer was determined by B. Nuber, H. Siebert, K. Weidenheimer and J. Weiss, Acta Crystal., B35, 1020 (1979). Interestingly, this isomer also crystallizes in the space group P212121 (z = 4), but the volume it occupies is only 782.09 A3, whereas the mer-isomer occupies a volume of 816.09 A3. Therefore, there is a difference of 34.81 A3/4 molecules or a volume difference per molecule, of 8.70 A3. If all other factors are equal, this would argue that crystals of the fac isomer are thermodynamically more stable since its higher density must be a reflection of its Madelung energy.

THE PHENOMENON OF CONGLOMERATE CRYSTALLIZATION. PART 43. THE CRYSTALLIZATION BEHAVIOR OF K[cis-α-Co(N-N′-Et2-Edda)(NO2)2] · 2H2O (I), {CS[cis-α-Co(Edda)(NO2)2]}2 · 3H2O (II), Rb[cis-α-Co(Edda)(NO2)2 · H2O (III) and NH4[cis-α-Co(Edda)(NO2)2] · 2H2O (IV)

Abstract K[cis-α-Co(Et2-edda)(NO2)2] · 2H2O (I), CoKO10N4C10H22, crystallizes in the space group P21/n(No. 14), with lattice constants: a = 7.339(2), b = 15.750(3), c = 15.492(4) A and β 101.65(2)°; V = 1753.86A3 and d(calc; MW = 456.34, Z = 4) = 1.728 g-cm−3. A total of 3335 data were collected over the range of 4° ≤ 2θ ≤ 50°; of these, 2553 (independent and with I > 3σ(I)) were used in the structural analysis. Data were corrected for absorption (μ = 12.688 cm−1) and the transmission coefficients ranged from 0.8860 to 0.9997. Final values of the residuals were R(F) = 0.0275 and Rw (F) = 0.0301. The anions of the racemic pairs in the unit cell have the chiroptical symbols A(δΛδ) and Δ(ΛδΛ). {Cs[cis-α-Co(edda)(NO2)2]}2 · 3H2O (II), Cs2Co2O19N8C8H18, crystallizes in the space group C2/c(No. 15), with lattice constants: a = 19.304(6), b = 10.992(4), c = 13.809 (5) A and β = 106.42(3)°; V = 2827.11 A3 and d(calc; MW = 913.95 Z = 4) = 2.147 g-cm−1. A total of 4192 data were collected over the range of 4° ≤ 2θ ...

CONTROL OF THE COORDINATION MODE OF NO2 − BY THE NATURE OF THE AMINE LIGAND. CRYSTAL STRUCTURE OF THE NEUTRAL ZIGZAG POLYMERIC COMPOUND [mer-Ni(N-(2-Aminoethyl)-1,3-Propanediamine)-(NO2)2] (I)

Abstract A polymeric zigzag complex, [mer-Ni(N-(2-aminoethyl)-l,3-propanediamine)(NO2)2] (I), containing a bridging u-nitro(N,0), was obtained and its crystal structure was determined. Magnetic studies show the compound is antiferromagnetic. These results contrast to those for [Ni(3,3′-diamino-N-methyldipropylamine)(NO2)2] (II), which is a monomer.