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Figure 4: Crystal structure of complex 4b. Thermal ellipsoids drawn at 30% probability. The hydrogen bonding network is also depicted on the right. A, which is also close to the metal centre of a nearby complex (F4’ — Cul is equal to 2.796(3) A). It is tempting to say that less than 2.60 A are enough to support the hypothesis of a Cu-PF. bond, also considering that in the literature similar distances have been addressed as such®”®®. However, in this case, the hexafluorophosphate anion seems to be mainly kept in place by three hydrogen bonds in the crystal state, with additional weak interactions with the copper centres above and below (Figure 4). We therefore suggest that the true nature of 4b is that of a divalent square planar cation. One hydroxide is present as a counterion. N1 —Cu1 — $3 and N3 — Cui -—S$1 angles measure 174.0(1)° and 174.3(1)° respectively. The hydrogen bonding network between the hydroxide, the hydrazine groups and hexafluorophosphate anion is composed of O1- H1:--F1 (2.68 A, 166.25°), N3-H3a---F2 (2.74 A, 143.91°), N3-H3b---F6 (2.89 A, 169.89°), N1-H1a---O1 (2.84 A, 170.39°), N1-H1b:--F1 (2.86 A, 175.34°). Cu1 atom is coplanar with the N1 — $1 — Cl1 — Cl2 mean plane (0.003 A displacement). During the refinement of the crystal structure of 4b, an effort was made to discriminate between the presence of an OH’ group and a water molecule. Fourier difference maps were not helpful for this purpose, and in fact the R values did not change significantly in the cases of OH or H2O. However, the negative charge of the OH is necessary for the electrostatic balance in the asymmetric unit. Also, assuming that there was a water molecule instead of a hydroxide ion, one of the two hydrogen atoms would not have been involved in any hydrogen bond. For these reasons, hydroxide was preferred. However, its existence in the crystal state is still not well understood.

Figure 4 Crystal structure of complex 4b. Thermal ellipsoids drawn at 30% probability. The hydrogen bonding network is also depicted on the right. A, which is also close to the metal centre of a nearby complex (F4’ — Cul is equal to 2.796(3) A). It is tempting to say that less than 2.60 A are enough to support the hypothesis of a Cu-PF. bond, also considering that in the literature similar distances have been addressed as such®”®®. However, in this case, the hexafluorophosphate anion seems to be mainly kept in place by three hydrogen bonds in the crystal state, with additional weak interactions with the copper centres above and below (Figure 4). We therefore suggest that the true nature of 4b is that of a divalent square planar cation. One hydroxide is present as a counterion. N1 —Cu1 — $3 and N3 — Cui -—S$1 angles measure 174.0(1)° and 174.3(1)° respectively. The hydrogen bonding network between the hydroxide, the hydrazine groups and hexafluorophosphate anion is composed of O1- H1:--F1 (2.68 A, 166.25°), N3-H3a---F2 (2.74 A, 143.91°), N3-H3b---F6 (2.89 A, 169.89°), N1-H1a---O1 (2.84 A, 170.39°), N1-H1b:--F1 (2.86 A, 175.34°). Cu1 atom is coplanar with the N1 — $1 — Cl1 — Cl2 mean plane (0.003 A displacement). During the refinement of the crystal structure of 4b, an effort was made to discriminate between the presence of an OH’ group and a water molecule. Fourier difference maps were not helpful for this purpose, and in fact the R values did not change significantly in the cases of OH or H2O. However, the negative charge of the OH is necessary for the electrostatic balance in the asymmetric unit. Also, assuming that there was a water molecule instead of a hydroxide ion, one of the two hydrogen atoms would not have been involved in any hydrogen bond. For these reasons, hydroxide was preferred. However, its existence in the crystal state is still not well understood.

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Scheme 1: Complexes 1-6 and their molecular structures. Compounds highlighted in blue are Cu(II) derivatives while yellow ones are Cu(|) derivatives. Complexes 3a, 4a, 4b and 6a are also depicted. Copper starting sources: CuCl2-2H20 (a), Cu(NO3)2°3H20 (b), CuSO4:5H20 (c), [Cu(CH3CN)a]PFe (d) [Cu(PPh3)2]NO3(a) and CuBr (f) Scheme 1 summarises the reactivity of the DTCZ ligand toward the different copper precursors. Copper(II) complexes (1-3) were efficiently produced through simple complexation reactions starting from different copper(II) salt precursors, including CuCl2-2H20, Cu(NO3)2- 3H2O and CuSO,: 5H20. Reactions were carried out by treating the pertinent precursor complex with a slight excess of DTCZ in ethanol solution at room temperature. In all cases, although the formation of the products was immediate, the reactions were
Scheme 1: Complexes 1-6 and their molecular structures. Compounds highlighted in blue are Cu(II) derivatives while yellow ones are Cu(|) derivatives. Complexes 3a, 4a, 4b and 6a are also depicted. Copper starting sources: CuCl2-2H20 (a), Cu(NO3)2°3H20 (b), CuSO4:5H20 (c), [Cu(CH3CN)a]PFe (d) [Cu(PPh3)2]NO3(a) and CuBr (f) Scheme 1 summarises the reactivity of the DTCZ ligand toward the different copper precursors. Copper(II) complexes (1-3) were efficiently produced through simple complexation reactions starting from different copper(II) salt precursors, including CuCl2-2H20, Cu(NO3)2- 3H2O and CuSO,: 5H20. Reactions were carried out by treating the pertinent precursor complex with a slight excess of DTCZ in ethanol solution at room temperature. In all cases, although the formation of the products was immediate, the reactions were
Table 1: Crystal data, data collection and structure refinement details for copper(Il) complexes 1, 3, 3a and 4b. Crystallography
Table 1: Crystal data, data collection and structure refinement details for copper(Il) complexes 1, 3, 3a and 4b. Crystallography
Table 2: Crystal data, data collection and structure refinement details for copper(|) complexes 4, 5, 6 and 6a complex 2 was also previously characterized®. The Cu — S bond length does not vary significantly between Cu(I) and Cu(II) complexes, (mean distance are 2.28 A for both) while Cu—N bond length is longer for Cu(l) complexes, suggesting a weaker bond (meat distances are 2.11 A and 2.00 A for copper(I) and copper(II), respectively). N2 —N1—Cu1 bond angles in Cu( complexes are also appreciably smaller (112.1°) than in Cu(II) complexes (115.4°). For all complexes, bon length C1 — S1 is compatible with a double bond character and C1 — N2 length is compatible with a singl bond character. The conformation of the Cul — N1 — N2 — C1 — S11 five-membered ring resulting from coppe chelation has been analysed considering the $1 — C1 — N2 plane, given the sp? character of the C1 carbon Copper‘(Il) complexes present a half-chair conformation, almost planar for 1 and 4b, while more pronounces for complex 3a. An even more pronounced half-chair conformation is present in one of the two five membered rings of complex 3. Interestingly, copper(l) complexes 4, 5 and 6 exclusively adopt the envelop: conformation, in which Cu1 is the tip of the envelope. Therefore, we suggest that the ring con formation i dependent on the metal oxidation state. The water as a solvate in the asymmetric units of 3a, 5 and 6 shoul derive from ambient moisture and/or from solvents, which were not anhydrous. Other features are discussec separately for Cu(II) and Cu(l) complexes, as below. dependent on the metal oxidation state. The water as a solvate in the asymmetric units of 3a, 5 and 6 should
Table 2: Crystal data, data collection and structure refinement details for copper(|) complexes 4, 5, 6 and 6a complex 2 was also previously characterized®. The Cu — S bond length does not vary significantly between Cu(I) and Cu(II) complexes, (mean distance are 2.28 A for both) while Cu—N bond length is longer for Cu(l) complexes, suggesting a weaker bond (meat distances are 2.11 A and 2.00 A for copper(I) and copper(II), respectively). N2 —N1—Cu1 bond angles in Cu( complexes are also appreciably smaller (112.1°) than in Cu(II) complexes (115.4°). For all complexes, bon length C1 — S1 is compatible with a double bond character and C1 — N2 length is compatible with a singl bond character. The conformation of the Cul — N1 — N2 — C1 — S11 five-membered ring resulting from coppe chelation has been analysed considering the $1 — C1 — N2 plane, given the sp? character of the C1 carbon Copper‘(Il) complexes present a half-chair conformation, almost planar for 1 and 4b, while more pronounces for complex 3a. An even more pronounced half-chair conformation is present in one of the two five membered rings of complex 3. Interestingly, copper(l) complexes 4, 5 and 6 exclusively adopt the envelop: conformation, in which Cu1 is the tip of the envelope. Therefore, we suggest that the ring con formation i dependent on the metal oxidation state. The water as a solvate in the asymmetric units of 3a, 5 and 6 shoul derive from ambient moisture and/or from solvents, which were not anhydrous. Other features are discussec separately for Cu(II) and Cu(l) complexes, as below. dependent on the metal oxidation state. The water as a solvate in the asymmetric units of 3a, 5 and 6 should
Table 3: Selected bond lengths (A) and angles (°) for copper(II) complexes. For disubstituted compounds 3 (*), 3a (+) and 4b (°) the parameters are reported twice, once for each ligand molecule. Table 4: Selected bond lengths (A) and angles (°) for copper(|) complexes. For the disubstituted compound 6 (#) the parameters are reported twice, once for each liganc molecule (complex 4 parameters are reported only once since the second ligand molecule is obtained by symmetry operations).
Table 3: Selected bond lengths (A) and angles (°) for copper(II) complexes. For disubstituted compounds 3 (*), 3a (+) and 4b (°) the parameters are reported twice, once for each ligand molecule. Table 4: Selected bond lengths (A) and angles (°) for copper(|) complexes. For the disubstituted compound 6 (#) the parameters are reported twice, once for each liganc molecule (complex 4 parameters are reported only once since the second ligand molecule is obtained by symmetry operations).
Crystal structures of copper(II) complexes
Crystal structures of copper(II) complexes
Figure 1: Crystal structure of complex 1. Thermal ellipsoids drawn at 30% probability. The polymeric chain in the solid state is depicted on the right, highlighting Cu1 - Cl2 solid-state interaction.
Figure 1: Crystal structure of complex 1. Thermal ellipsoids drawn at 30% probability. The polymeric chain in the solid state is depicted on the right, highlighting Cu1 - Cl2 solid-state interaction.
Figure 2: Crystal structure of complex 3. Thermal ellipsoids drawn at 30% probability. The hydrogen bonding network is also depicted on the right
Figure 2: Crystal structure of complex 3. Thermal ellipsoids drawn at 30% probability. The hydrogen bonding network is also depicted on the right
Figure 3: Crystal structure of complex 3a. Thermal ellipsoids drawn at 30% probability. Water channels in the crystal state viewed along the c and a axis are also depicted on the right.
Figure 3: Crystal structure of complex 3a. Thermal ellipsoids drawn at 30% probability. Water channels in the crystal state viewed along the c and a axis are also depicted on the right.
Figure 5: Crystal structure of complex 4. Thermal ellipsoids drawn at 30% probability. The hydrogen bonding network is also depicted on the right. A, 148.51°), resulting in the formation of water channels in the crystal state along the b axis, like in complex
Figure 5: Crystal structure of complex 4. Thermal ellipsoids drawn at 30% probability. The hydrogen bonding network is also depicted on the right. A, 148.51°), resulting in the formation of water channels in the crystal state along the b axis, like in complex
Figure 6: Crystal structure of complex 6. Thermal ellipsoids drawn at 30% probability. Water channels in the crystal state viewed along the a and b axis are also depicted on the right. In complex 5, the coordination sphere around the Cu(I) centre is defined by two phosphorus atoms fron wo triphenylphosphine groups, a sulphur atom and a nitrogen atom from the DTCZ ligand resulting in < listorted tetrahedral geometry; a nitrate is present as a counterion. The nitrate, a solvated water molecule ind the NH2 hydrazinic group of DTCZ interact closely, and they also pair with a second nitrate, water anc 1\ydrazine group of a nearby molecule (Figure 7). The hydrogen bonding network is composed of N1-H1b::-O1 2.94 A, 165.39°), O1-H1c:--03 (2.84 A, 156.66°), N1-H1a---O2 (2.96 A, 156.50’). As presented in Table 4, N1 - [u1 — S1 bite angle is significantly lower than that of the other complexes due to the steric effect of the bulky riphenylphosphine ligands, and Cu —S bond length is significantly longer as well. From the solvent evaporation of an acetonitrile solution of complex 6, dark yellow crystals of 6a were alsc
Figure 6: Crystal structure of complex 6. Thermal ellipsoids drawn at 30% probability. Water channels in the crystal state viewed along the a and b axis are also depicted on the right. In complex 5, the coordination sphere around the Cu(I) centre is defined by two phosphorus atoms fron wo triphenylphosphine groups, a sulphur atom and a nitrogen atom from the DTCZ ligand resulting in < listorted tetrahedral geometry; a nitrate is present as a counterion. The nitrate, a solvated water molecule ind the NH2 hydrazinic group of DTCZ interact closely, and they also pair with a second nitrate, water anc 1\ydrazine group of a nearby molecule (Figure 7). The hydrogen bonding network is composed of N1-H1b::-O1 2.94 A, 165.39°), O1-H1c:--03 (2.84 A, 156.66°), N1-H1a---O2 (2.96 A, 156.50’). As presented in Table 4, N1 - [u1 — S1 bite angle is significantly lower than that of the other complexes due to the steric effect of the bulky riphenylphosphine ligands, and Cu —S bond length is significantly longer as well. From the solvent evaporation of an acetonitrile solution of complex 6, dark yellow crystals of 6a were alsc
Figure 7: Crystal structure of complex 5. Thermal ellipsoids drawn at 30% probability. The hydrogen bonding network is also depicted on the right. Triphenylphosphine groups have been drawn as sticks for clarity.
Figure 7: Crystal structure of complex 5. Thermal ellipsoids drawn at 30% probability. The hydrogen bonding network is also depicted on the right. Triphenylphosphine groups have been drawn as sticks for clarity.
Figure 8: Crystal structure of complex 6a. Thermal ellipsoids drawn at 30% probability. The polymeric chain in the solid state, emphasizing tetrahedral units, is also depicted on the right.
Figure 8: Crystal structure of complex 6a. Thermal ellipsoids drawn at 30% probability. The polymeric chain in the solid state, emphasizing tetrahedral units, is also depicted on the right.
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