James Cetrullo

The phenomenon of conglomerate crystallization. XII. Spontaneous resolution in coordination compounds. X. The structure and absolute configuration of δ(λδλ)(+)589-[cis-α-Co(trien)(NO2)2]Cl·H2O and of Λ(δλδ)(−)589-[cis-α-Co(trien)(NO2)2]I·H2O

Abstract Compounds [cis-α-Co(trien)(NO2)2]X·H2O (with X  I and Cl) are obtained as conglomerates when aqueous solutions of these species are crystallized either by evaporation at room temperature or cooled in a refrigerator at ca. 2 °C. Both crystallize in the orthorhombic system, space group P212121. The chloride crystal examined is the enantiomer of that previously reported and this study merely verifies that the crystalline material obtained consists of a conglomerate; thus, little additional discussion is necessary for this compound. The cell constants of the iodide are: a=8.041(3), b=13.013(3) and c=14.169(2) A; V=1482.64 A3 and D(calc;z=4)=1.980 g cm−3. The structure of the iodide was refined with 1536 independent data to final discrepancy indices of R=0.027 and Rw= 0.026. The chloride and iodide are isomorphous and nearly isostructural — the halide anions are not placed at the exact same fractional coordinates and this results in a small, but meaningful, difference in the hydrogen bonding between halide and the secondary amino hydrogens with which they interact in the lattice. The fact that the halides interact in the solid with the secondary nitrogen protons is significant for the mechanism of conglomerate crystallization since in the nitrates, which crystallize as racemates, the NO3− anions form strong hydrogen bonds to the terminal- (primary) −NH2 hydrogens. It has been postulated in the past that intramolecular hydrogen bonds between the cis-(NO2) oxygens and the primary −NH2 hydrogens is responsible for the conglomerate crystallization of these compounds. Finally, solution 1H NMR studies by Yoneda and associates revealed that the halides of related bis- ethylenediamine species seemed to be associated with the basal plane amino hydrogens trans to the cis-X2 moiety. We observe, in the solid state, the same type of preferential interaction between halide and amino hydrogens trans to the −NO2 ligands. Thus, the ion pair observed in out solid state studies seems to persist in solution sufficiently to be detectable by NMR measurements — a behaviour never documented previously.

The phenomenon of conglomerate crystallization. VII. Clavic dissymmetry in coordination compounds.V. An investigation of the crystallization behavior of [cis-β-Co(triethylenetetramine)(NO2)2]X (X = I, NO3) and the crystal structure of racemic [cis-β-Co(trien)(NO2)2]NO3

Abstract [ cis -β-Co(trien)(NO 2 ) 2 ]X (X=I − , NO 3 − ) were prepared and examined crystallographically to ascertain whether or not they undergo conglomerate crystallization. As predicted earlier, the nitrate crystallizes as a racemate: space group P 2 1 / n with cell constants of a = 7.604(3), b = 13.019(2), c = 14.472- (3) A, β = 98.13(3)°, V = 1418.26 A 3 , D c = 1.682g cm −3 , Z = 4. The bonding parameters and overall stereochemistry of the [ cis -β-Co(trien)] fragment of the cation are essentially identical with that of resolved and racemic salts sharing this common fragment, proving that lattice forces do not play a major role in shaping its geometrical features. The iodide crystallizes in the monoclinic space group Cc , with cell constants of a = 15.65(1), b = 6.53(3), c = 13.095(7) A, β = 100.59(5)°, V = 1314.72 A 3 , D c =2.142 g cm −3 , Z = 4. The crystals of the iodide are not only extremely small but of poor quality, allowing only a qualitative solution of the structure which, nonetheless, is sufficient to establish that this salt also crystallizes as a racemate - a surprise in view of the fact that the α isomer crystallizes as a conglomerate; thus, there is a major difference in the crystallization behaviour of this pair of geometrical isomers.

THE PHENOMENON OF CONGLOMERATE CRYSTALLIZATION. XXVII. THE EFFECT OF CHARGE COMPENSATING ANION ON THE CRYSTALLIZATION BEHAVIOUR OF [Co(en)2ox]-Cl·4H2O, [Co(en)2ox]Br·H2O, [Co(en)2ox]PF6 AND [Co(en)2ox]I

Abstract [Co(en)2ox]Cl·4H2O (I) and [Co(en)2ox]Br·H2O (II), crustallize from water at 21°C as conglomerates, space group P212121. Their structures and absolute configurations were determined by refinement of data using both enantiomeric configurations. [Co(en)2ox]PF6 (III) crystallizes as a racemate, space group P21/c. [Co(en)2ox]I (IV) crystallizes in both of the monoclinic space groups C2 and C2/c, in agreement with the phase diagram studies of Yamanari, et al. (see ref. 4). However, we have not been successful in crystallographic studies of this substance since in neither case was it possible to obtain ordered crystals. The conglomerate crystallization pathway selected by (I) and (II), and probably (IV), is shown to be the result of inter-cationic, three-point attachments reminiscent of that postulated as the origin of enzymatic chiral recognition. In this process, spiral strings are formed which resemble polypeptide helices, and which are stitched together by the counternions (and/or waters of crystal...

The phenomenon of conglomerate crystallization. : XII. Spontaneous resolution in coordination compounds. IX. The structure of racemic [cis-α-Rh(trien)(N02)2] Cl

The title compound crystallizes in the monoclinic space group P21/n with ceil constants: a = 9.212(7), b = 14.250(13), c = 10.117(3) A and β = 92.46(4)°; V = 1326.82 A3 and D(calc., Z = 4) = 1.885 gm cm−3. A total of 3407 data were collected over the range of 4° ⩽ 2θ ⩽ 55°; of these, 2786 (independent and with I ⩾ 3σ(I)) were used in the structural analysis. The final R(F) and Rw(F) residuals were, respectively 0.032 and 0.052. The Rh-N(NO2) distances are 2.030(1) and 2.026(1) A, while the RhN(amine) distances, rans to the NO2 nitrogens are 2.090(1) and 2.091(1) A, values distinctly longer than the other two RhN distances (2.078(1) and 2.060(1) A). The latter are the RhN distances to the terminalNH2 ligands which are trans to each other. Thus, we observe a trans effect, which is more pronounced in the Rh than the Co analogue. Parallel with the increase in metalN distances (going from Co to Rh) is an increase in the torsional angles CNCN which, in the former case, are 42.6, −40.4 and 39.3° while in the Rh compound are −50.7,41.2 and −48.2°. Interestingly, the metal NC, NCC and CCN angles are little altered. The NO distances are 1.214(1), 1.240(1), 1.236(1) and 1.212(1) A, which are nearly identical with those found for the analogous Co isomer. The CN are 1.485(2), 1.495(2), 1.507(2), 1.495(2), 1.488(2) and 1.494(2) A, while the CC bonds are 1.516(2), 1.528(2) and 1.515(2) A. These values are also comparable with those obtained for the Co isomer and, in fact, the pattern of the bonds is nearly identical in both. Given the above, it is revealing that the Rh compound crystallizes as a racemate. We attribute this difference to the weaker hydrogen bonding between the oxygens of the NO2 ligands and the terminal NH2 hydrogens, a situation created by the inherently longer RhN bonds. In fact, the shortest intramolecular H bond present is O3⋯H2, which is ca. 2.45 A and for which the < N1—H2⋯O3 is 111°, values that render this ‘bond’ meaningless. The shortest hydrogen bond is an intermolecular bond between 02 and H17 on an adjacent molecule (2.17 A) and the, < N4—H17⋯O = 174°. As was the case with the Co analogue, the Cl− anion is associated with the hydrogens of the secondary nitrogens (trans to the −NO2) ligands, the Cl⋯H7 distance being 2.16(2) A and the < Cl⋯H7—N2 = 164°.

The phenomenon of conglomerate crystallization. XV. Spontaneous resolution in coordination compounds. XIII. The crystallization behaviour and the crystal and molecular structure of Δ(λδ)-cis-Rh(en)2(NO2)2]Cl

Abstract The title compound, I, crystallizes in the monoclinic space group P21 with cell constants: a = 6.599(3), b = 11.121(2), c = 8.375(1) A and β = 106.35(2)°; V = 589.74 A3 and D(calc; Z = 2) = 1.974 g cm−3. The compound is isomorphous and isostructural with its Co analogue. A total of 2982 data were collected over the range of 4°  20  70°; of these, 2537 (independent and with I ⩾ 3σ(I)) were used in the structural analysis. Data were corrected for absorption (μ = 16.6 cm−1) and the relative transmission coefficients ranged from 1.000 to 0.9504. Refinement was carried out for both enantiomeric configurations and the crystal used was found to contain cations with Δ(λδ) absolute configuration. The final R(F) and Rw(F) residuals were, respectively 0.0220 and 0.0239 for (−−−; i.e.Δ(λδ)) and 0.0231 AND 0.0317 FOR (+++; i.e.Λ(δλ)). Thus, the former was selected as correct for our specimen. In the case of I, as well as in the Co derivative [cis-Co(en)2(NO2)2]Cl (II), the conformation of one of the rings is opposite that expected for the lowest energy conformation, which in the current case should be Δ(λλ)). The RhN(NO)2 distances are 2.020(2) and 2.010(2) A, while the RhN(amine) distances, trans to the NO2 ligands are 2.085(2) and 2.093(1) A, values distinctly longer than the other two RhN distances (2.064(1) and 2.068(1) A). The latter are the RhN distances to the terminalNH2 ligands located trans to each other. Thus, we observe a trans effect, which is more pronounced in I than in II, and which is of comparable magnitude to that observed in the case of the trien derivative, [cis-α-Rh(trien)(NO2)2]Cl(III). Parallel with an increase in metalN distances in going from [cis-α-Co(trien)NO2)2]Cl·H2) (IV) to (III) is an increase in the torsional angles of the outer rings (NCCN) of about 10°. Comparison of these parameters in I and II reveal that this change is not so marked for this pair since in I they are −54.9° and 52.8° while in II they are 50.2° and −48.1°; i.e. a change of only 4°. This important difference between trien and en derivatives is caused by the presence of the central five-membered ring, which for compounds III and IV remains largely unchanged, except for the metalN distances. The NO bond lengths are 1.244(3), 1.220)(2), 1.237(2) and 1.211(2) A, which are similar to those found for the analogous Co isomer. The CN bond lengths are 1.492(3), 1.474(2), 1.486(2) and 1.475(2) A, while the CC bonds are 1.509(3) and 1.524(3) A. These values are also comparable with those obtained for the Co isomer and, in fact, the pattern of the bonds is nearly identical in both, including the common feature of having a longer CC bond for the en ring with the conformation opposite that expected. As was the case with the Co analogue, the Cl− anion is associated with the hydrogens of the secondary nitrogen (trans to the −NO2) ligands, the Cl…H7 distance being 2.18(3) A and the

The phenomenon of conglomerate crystallization. XI: Clavic dissymmetry in coordination compounds. VIII: An investigation of the crystallization, conformational and configurational behaviour of [mer-Co(1,5-diamino-3-azapentane)(NO2)3]

Abstract [mer-Co(dien)(NO2)3] does not form conglomerates when crystallized from water at a variety of temperatures; instead, it crystallizes in the racemic space group Pbca. Crystals obatined at 21 °C, and studied by X-ray diffraction at 16 °C, crystallize with unit cell parameters of a = 13.030(3), b = 12.688(2) and c = 13.172(3) A; V = 2177.66 A3, D(calc; M = 300.12 g mol−1; Z = 8) = 1.831 g cm−3. Data were collected with Mo Kα (4° ⩽ 20 ⩽ 50°; 2268 data), corrected for absorption (μ = 16.01 cm−1; relative transmission coefficients range from 0.9026 to 1.0000) producing a reduced set of 1556 reflections for which I ⩾ 3σ(I). The structure was solved by the Patterson method and refined to R(F) = 0.0282 and Rw(F) = 0.0330, using as weights w = [σ(Fo)]−2. The Co(dien) fragment has the shape of pleated sheet in which the conformation of the two (NHCH2CH2NH2) fragments are δ and λ or their inverse. The two CoN(H2) distances are identical (1.942(1) and 1.944(1) A) and shorter than the CoN(H) distance of 1.952(1) A. The two mutually trans CoN(O2) bonds are 1.97(1) and 1.931(1) A, reflecting an interesting molecular asymmetry; the effect in question being the bending of one of the NO2 ligands towards the NH2CoNH2 edge of the molecule so as to maximize the strength of the bonds. The bent NO2(N4) is the one with the long CoN distance. Finally, the unique CoN(O2) distance is 1.914(1) A, shorter than either of the previous ones and a clear example of the trans effect. The geometry at Co is a distorted octahedron, as expected. The largest distortion being the angle N1CoN3(169.9(6)°) defined by the two terminalNH2 ligands. Other angular distortions are smaller. The NC distances range from 1.473(2) to 1.493(2) A and the two CC distances are 1.505(2) and 1.498(2) A. Refined NH (terminal) distances range from 0.81(2) to 0.88(2) A and the secondary NH distance is 0.90(1) A. CH distances range from 0.90(2) to 1.05(2) A.

The phenomenon of conglomerate crystallization Part XXXI. The crystallization behavior of [cis-Co(en)2(NO2)2Br and of [cis-α-Co(triethylenetetramine)(NO2)2](NO3)·13H2O: counter-ion effects on crystallization pathway of racemate solutions

Abstract In accordance with predictions made in previous studies of conglomerate crystallization of coordination compounds, racemic solutions of [cis-Co(en)2(NO2)2]Br crystallize as a conglomerate (homochiral crystals, space group P21), whereas racemic solutions of [cis-α-Co(triethylenetetramine)(NO 2 ) 2 ](NO 3 )· 1 3 H 2 O crystallize as a racemate (heterochiral crystals, space group P2 1 c ). Intra- and intermolecular hydrogen-bonded interactions are shown to control the crystallization pathway these substances select, and the counter anion used is shown to play a role in such selection.

The phenomenon of conglomerate crystallization. Part 40: The crystallization behavior oftrans- Co(III) amines (+)546-trans-[Co(3,2,3-tet)(NO2)2]Cl·3H2O (I), (−)589-trans-[Co(3,2,3-tet)Cl2]NO3 (II), and of (+)546-trans-[Co(3,2,3-tet)(NO2)2]NO3 (III)

A racemic solution of (I) crystallizes as a conglomerate from which a crystal we selected was found to be (+)546-trans-[Co(3,2,3-tet)(NO2)2]Cl·3H2O (I), CoClO7N6C8H28. It crystallizes in the enantiomorphic space groupP2l2l2l, with lattice constantsa=18.501(15) å,b=14.433(2) å, andc=6.441(3) å;V=1720.07 å3 andd(calc. M.W.=414.73,Z=4)=1.601 g cm−3. A total of 2305 data were collected over the range of 4‡≤2θ ≤55‡; of these, 1724 (independent and withI > 3σ(I)) were used in the structural analysis. Data were corrected for absorption (Μ=11.920 cm−1), and the relative transmission coefficients ranged from 0.8258 to 0.9565. Refinement was carried out for both lattice enantiomorphs, and at this stage theR(F) andRw(F) residuals were, respectively, 0.0381 and 0.0479 for (+ + +) and 0.0448 and 0.0532 for (− − −). Thus, the former was selected as correct for our specimen, and the final cycle of refinement with the (+ + +) model converged toR(F) andRw(F) of 0.0315 and 0.0365. A racemic solution of (II) crystallizes as a conglomerate from which a crystal we selected was found to be (−)589-trans-[Co(3,2,3-tet)Cl2]NO3 (II), CoCl2O3N5C8H22. It crystallizes in the enantiomorphic space groujp,P2l with lattice constantsa=6.395(2) å,b=8.886(2) å,c=13.185(2) å, andΒ=99.24(2)‡;V=739.59 å3 andd(calc. M.W.=366.14,Z=2)=1.646 g cm−3. A total of 2912 data were collected over the range of 4‡<2θ<64‡; of these, 2147 (independent and withI≥3σ(I)) were used in the structural analysis. Data were corrected for absorption (Μ =15.424 cm−1), and the relative transmission coefficients ranged from 0.9632 to 0.9985. Refinement was carried out for both lattice enantiomorphs, and the finalR(F) andRw(F) residuals were, respectively, 0.0326 and 0.0328 for (+ + +) and 0.0347 and 0.0348 for (− − −). Thus, the (+ + +) was selected as correct for our specimen. A racemic solution of (III) crystallizes as a conglomerate from which a crystal we selected was found to be (+)589-trans-[Co(3,2,3-tet)(NO2)2]NO3 (III), CoO7N7C8H22. It crystallizes in the enantiomorphic space group,P2l with lattice constantsa=6.295(1) å, b=15.108(3) å,c=8.029(1) å, andΒ=100.28(2)‡;V=751.35 å3 andd(calc. M.W.=387.24,Z=2)=1.712 g cm−3. A total of 2393 data were collected over the range of 4‡≤2θ≤60‡; of these, 1869 (independent and withI≥3σ(I)) were used in the structural analysis. Data were corrected for absorption (Μ=11.859 cm−1), and the relative transmission coefficients ranged from 0.8814 to 0.9976. Refinement was carried out for both lattice enantiomorphs and the finalR(F) andRw(F) residuals were, respectively, 0.0463 and 0.0482 for (+ + +) and 0.0441 and 0.0442 for (− − −). Thus, the latter was selected as correct for our specimen, and the final cycle of refinement with the (− − −) model converged toR(F) andRw(F) of 0.0436 and 0.0421. For all three compounds, the six-membered rings are chairs; the secondary nitrogens are chiral centers, and the five-membered rings are ordered and conformationally dissymmetric, as expected. Coincidentally, in (I), (II), and (III) the central rings are right-handed helices withδ(+50.0‡),δ(+53.3‡), andδ(+48.3‡), respectively. Thus, the secondary nitrogens of all three cations are (R), rendering the cations chiral. The incidence of conglomerate crystallization intrans coordination compounds is rare, and those known are asymmetrically substituted (see Ref. 4 for the four known cases). Thus, the incidence of such crystallization mode in a new series of [trans- Co(amine ligands)X2]+ cations bearing symmetrical pairs oftrans ligands was an unexpected and welcomed event. In all three cases, the counteranions are bonded to the hydrogens of the terminal -NH2 moieties, thus forming an overall entity which resembles a macrocycle. In fact, parallels between the crystallization behavior of our compounds and that of macrocycles bearing related fragments is discussed. Finally, in the three compounds, homochiral cations are linked into infinite strings by hydrogen bonds between the axial ligands and amino hydrogens on adjacent cations of the string. In turn, strings are stitched together by the counteranions which form bonds with amino hydrogens on cations of adjacent strings.

The Phenomenon of Conglomerate Crystallization. XVII. Clavic Dissymmetry in Coordination Compounds. XV. The Effect of the Charge Compensating Ions on the Phenomenon of Conglomerate Crystallization

Abstract In this report, we discuss the effect of the counter ion on the crystallization behaviour of chiral ions which may produce racemic or conglomerate crystals. We demonstrate that the counter ion is often capable of influencing the crystallization pathway and provide examples of substances in which the same chiral ion produces enantiomorphic crystals or racemic crystals depending on the nature of the counter ion. Moreover, we demonstrate that the crystal structures of such species amply demonstrate the reasons for such differences in crystallization pathway. In the species selected for the illustrations, the underlying phenomenon being influenced by the choice of counter ion is hydrogen bonding. This summary provides examples of counter ion pairs as varied as halides vs NO3 −, halides vs NO2 −, K+1 vs Ag+, etc., influencing the choice of crystallization pathway. Also, we illustrate the fact that the same ion (i.e., NO3 −) can play either a positive or a negative role in such a selection.

The phenomenon of conglomerate crystallization. XIX. Clavic dissymmetry in coordination compounds. XVII

Abstract[Co(NH3)4(oxalato)]NO3·H2O (1) crystallizes as a conglomerate in space groupP212121 with unit cell constants ofa=7.944(3),b=9.904(11), andc=12.700(2) Å;V=999.15 Å3;d(calc.;z=4)=1.968 g cm−3. [Co(NH3)4(oxalato)]¦·H2O (2) crystallizes in space groupP22/n with cell constants ofa=7.285(1),b=9.959(3),c=15.410(5) Å;β=102.63(2)° andV=1090.98 Å3; d(calc;z=4) = 2.192 g cm−3. Data were collected over the ranges of 4°≤2Θ≤70° and 4°≤2Θ≤55°, respectively for compounds1 and2. This resulted in a total of 2515 and 2823 data for the solution and refinement of the structures of compounds1 and2, respectively. When the refinements converged, the finalR(F) andRw(F) values were, respectively, 0.073 and 0.080 for1 and 0.0378 and 0.0353 for2.Since neither data set was sufficiently good to give a sensible set of positions for all of the hydrogens, the stereochemistry of the two cations could only be defined by the positions of the heavy atoms. In the absence of reliable amine hydrogen positions, N(amine)-O(nitrate and oxalate) distances were examined. Close N(amine)-O(nitrate and oxalate) contacts indicate the presence of a network of significant hydrogen bonds in1. The N-O distances for compound2 also show the presence of hydrogen bonding between the amines and the oxalate ligand and water; however, the bonds are not of the same magnitude as the interactions involving the nitrate oxygens in1. Despite the similarity between the cations of1 and2, the Co-N distances in the two do not exhibit the same pattern. In1, the Co-N distances for amines trans to one another are shorter than the Co-N distances for amines trans to oxalate oxygens; this effect is reversed in2.