English

• 0.   Introduction

  Over the last few years, there are plentiful researches of luminescence metal complexes that are expected to be used in materials science, light-emitting diodes and Nixie tubes^[1-3]. Cu(Ⅰ) complexes, compared with precious metal complexes such as Os(Ⅲ) complexes, Ir(Ⅲ) complexes and Pt(Ⅳ) complexes, have wide sources, low toxicity and low price, and are widely regarded as a reasonable substitute for precious metal complexes^[4-10]. Up to now, plenty of mixed-ligand Cu diphosphine diimine complexes such as [Cu(N^N) (P^P)]⁺ system have been reported and usually have good luminescence properties^[11-12].

  1, 3-Bis(diphenylphosphanyl)propane (dppp), a diphosphine ligand, can coordinate as either bridged ligand or chelating ligand. According to the hard-soft - acid - base (HSAB) theory, dppp can easily coordinate with Cu(Ⅰ) to help improving crystal quality. The diimine ligands, due to their strong chelate coordination ability, 1, 10 - phenanthroline (phen) and its derivatives usually have been used as chelating ligands to coordinate with Cu ^[13-15]. 1, 10- phenanthroline and its derivatives have low π * orbital energy, and often show metal-to-ligand charge transfer (MLCT) characteristics. As for [Cu(N^N)(P^P)]⁺ complexes, since the work of McMillin et al., Cu(Ⅰ) heteroleptic complexes constructed by phen and its derivatives are too numerous to enumerate. People have found that function groups at 2-position or 9-position of phen can efficiently reduce the distortion of configuration of metal center, therefore improving the photoluminescence quantum yield (PLQY) of complexes. Besides, function groups in other positions also have an impact on the property of complexes^{[11-13, 26]}. Herein, 2, 9-dimethyl-1, 10-phenanthroline (dmp) and 4, 7-diphenyl-1, 10-diazaphenanthrene (Bphen) were chosen to synthesize two complexes to make a comparsion of their properties (Scheme 1).

  Scheme 1

  

  Scheme 1.  Structures of the ligands

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  In our previous studies, we have reported some Cu(Ⅰ) complexes with novel structure and good luminescence properties. In this article, two novel Cu(Ⅰ) complexes, [Cu(dppp)(Bphen)]Cl·1.8CH₃OH (1) and [Cu₂(CN)₂(dppp)(dmp)₂]·2.5CH₃OH(2), have been synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy, 1H NMR and 31P NMR spectroscopy, fluorescence spectra and terahertz time - domain spectroscopy (THz - TDS). THz - TDS is a vibrational spectroscopy, which is used to detect the vibrational modes in the far - infrared and sub - millimeter region of the electro - magnetic spec- trum. Therefore, THz-TDS is pretty helpful to describe the structure and properties of polar compounds^[16].

  1.   Experimental

  1.1   Materials and measurements

  All commercially available starting materials were used as received, and solvents were used without furthermore treatment. FT - IR spectra (KBr pellets) were measured on a Perkin-Elmer infrared spectrometer. C, H and N elemental analyses were carried out on an Ele- mentar Vario MICRO CUBE (Germany) elemental analyzer. Thermogravimetric analysis was performed on a DTG - 60AH in the nitrogen atmosphere. The test temperature increased from 25 to 800 ℃ at a rate of 10 ℃· min^-1. Room - temperature fluorescence spectra were measured on F - 4500 FL Spectrophotometer. ¹H NMR was recorded at room temperature with a Bruker DPX 600 spectrometer. The THz-TDS spectra were recorded on the THz time domain device of Minzu University of China, based on photoconductive switches for generation and electro-optical crystal detection of the farinfrared light, effective frequency in a range of 0.2~2.8 THz^[17-18].

  1.2   Synthesis of [Cu(dppp)(Bphen)]Cl·1.8CH₃OH (1)

  A mixture of CuCl (0.019 8 g, 0.2 mmol), dppp (0.082 5 g, 0.2 mmol) and Bphen (0.066 5 g, 0.2 mmol) were dissolved in the mixed solvents of 5 mL CH₂Cl₂ and 5 mL CH₃OH. The mixture was stirred for 6 h and filtered. Orange crystals of 1 were obtained from the filtrate at room temperature for about forty days. Yield: 81%. Element analysis Calcd. for C₅₂H₄₆ClCuN₂OP₂·0.8CH₃OH(%): C, 70.35; H, 5.50; N, 3.11. Found(%): C, 70.86; H, 5.34; N, 3.17. IR data (KBr pellets, cm^-1): 3 424s, 3 052w, 2 904w, 1 616m, 1 434m, 1 385w, 1 159w, 1 098m, 967w, 834w, 767m, 742s, 699s, 574 m, 512s, 486s. ¹H NMR (600 MHz, DMSO-d₆, 298 K): δ 2.49~3.30 (m, CH₃ from CH₃OH, including solvent signals), 6.76~8.00 (m, CH_benzene from dppp and Bphen), 9.03~9.55 (m, heterocyclic hydrogen from Bphen). ³¹P NMR (600 MHz, DMSO - d₆, 298 K): δ -6.99 (s, phos- phorus from dppp).

  1.3   Synthesis of [Cu₂(CN)₂(dppp) (dmp)₂]·2.5CH₃OH (2)

  Similiar to 1, complex 2 was prepared by the reaction of CuCN (0.035 8 g, 0.4 mmol), dppp (0.082 5 g, 0.2 mmol) and dmp (0.083 4 g, 0.4 mmol) in the mixed solvents of 5 mL CH₂Cl₂ and 5 mL CH₃OH. About twenty days after filtration, yellow crystals were collected from the filter liquor. Yield: 73%. Element analysis Calcd. for C₅₉H₅₈Cu₂N₆O₂P₂·0.5CH₃OH(%): C, 65.67; H, 5.56; N, 7.72. Found(%): C, 65.72; H, 5.51; N, 7.76. IR data (KBr pellets, cm^-1): 3 469s, 2 096m, 1 622m, 1 588m, 1 500m, 1 434m, 1 097w, 857m, 744m, 697s, 519m, 480w. ¹H NMR (600 MHz, DMSO-d₆, 298 K): δ 1.03~1.09 (m, CH₂ from dppp), 2.37~2.53 (s, CH₃ from dmp), 3.14~3.48 (m, CH₃ from CH₃OH), 6.68~7.39 (m, CH_benzene from dppp), 7.69~7.80 (m, heterocylic hydrogen from dppp and dmp). ³¹P NMR (600 MHz, DMSO-d₆, 298K): δ -6.99 (s, phosphorus from dppp).

  1.4   Structure determination

  X-ray crystallographic studies of complexes 1 and 2 were performed on a Brucker SMART diffractometer equipped with 1000 CCD area detector with a graphite-monochromated Mo Kα (λ=0.071 073 nm) by scanning to collect independent diffraction point. Semi - empirical absorption corrections were applied using SADABS program^[19]. All structures were resolved by direct approaches and refined using SHELX-2018 package^[20-21]. Metal atom centers were located from the E-maps and other non - hydrogen atoms were located in successive difference Fourier synthesis. The final refinements were performed by full-matrix least-squares methods with anisotropic thermal parameters for non-hydrogen atoms on F². To model the structure, the reflection contributions from the part of CH₃OH molecules were removed using the program PLATON, function SQUEEZE, which proved that there were 100 electrons for 1 and 57 electrons for 2. These electrons were assigned to approximately 0.8 CH₃OH molecules for 1 and 0.5 CH₃OH molecules for 2 of the asymmetric unit (Z=4). Moreover, the calculated CH₃OH molecules was in good agreement with data from thermogravimetric and elemental analysis (Fig. 1). Further crystallo-graphic data and experimental details for structural analyses of all complexes are summarized in Table 1. Selected bond distances and angles are listed in Table 2.

  Figure 1

  

  Figure 1.  Thermogravimetric analysis of complexes 1 and 2

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  Table 1

  

  Table 1.  Crystallographic data of complexes 1 and 2

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  Complex	1	2
  Formula	C52H46ClCuN2OP2	C59H58Cu2N6O2P2
  Formular weight	875.84	1 072.13
  T/K	103(2)	105(2)
  Crystal system	Monoclinic	Monoclinic
  Space group	P21	C2/c
  Crystal size/mm	0.35×0.35×0.4	0.08×0.55×0.6
  a/nm	1.173 13(5)	2.491 92(14)
  b/nm	1.942 58(6)	1.008 24(5)
  c/nm	2.108 79(8)	2.159 47(9)
  β/(°)	104.059(5)	102.636(5)
  V/nm3	4.661 8(3)	5.294 2(5)
  Z	4	4
  F(000)	1 824.0	2 232
  Goodness-of-fit on F2	0.983	1.087
  Rint	0.090 1	0.041 9
  R1 [I > 2σ(I)]a	0.059 7	0.065 9
  wR2 [I > 2σ(I)]b	0.106 9	0.156 2
  R1 (all data)a	0.101 5	0.083 7
  wR2 (all data)b	0.125 2	0.166 5
  aR1=∑(||Fo|-|Fc||)/∑|Fo|; bwR=[∑w(|Fo|2-|Fc|2)2/∑w(Fo2)]1/2.

  Table 2

  

  Table 2.  Selected bond lengths (nm) and bond angles (°) for complexes 1 and 2

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  1
  Cu1—P1	0.220 58(10)	Cu1—P2	0.225 08(10)	Cu1—N1	0.204 7(3)
  Cu1—N1	0.204 3(3)
  P1—Cu1—P1	103.91(4)	P1—Cu1—N1	119.71(8)	P1—Cu1—N2	131.28(8)
  P2—Cu1—N1	102.17(8)	P2—Cu1—N2	114.42(8)	N1—Cu1—N2	81.10(11)
  2
  Cu1—P1	0.225 76(14)	Cu1—C28	0.191 50(64)	Cu1—N1	0.210 31(43)
  Cu1—N2	0.210 24(51)
  P1—Cu1—C28	122.84(19)	P1—Cu1—N1	106.22(12)	P1—Cu1—N2	100.04(12)
  C28—Cu1—N1	118.0(2)	C28—Cu1—N2	120.52(23)	N1—Cu1—N2	80.52(18)

  2.   Results and discussion

  2.1   Syntheses of the complexes

  It is known to all that the structures of Cu com- plexes are influenced by ligands and anions. In our researches, various copper salts (CuCl, CuCN) were mixed with the same diphosphine ligand (dppp) and similar diimine ligands (Bphen, dmp). As shown in Scheme 2, Complex 1 was synthesized by one-pot reaction that adding CuCl, dppp and Bphen to CH₂Cl₂ and CH₃OH (1∶1, V/V). Complex 2 was similarly prepared as for complex 1 by using CuCN in place of CuCl and using dmp in place of Bphen. Complex 1 is mononuclear structure, yet complex 2 is a dinuclear complex. In the respect of our report, the anions and diimine ligands make a difference to the structures of complexes 1 and 2. Both the complexes are stable in the air and can be stored for a long term.

  Scheme 2

  

  Scheme 2.  Syntheses of complexes 1 and 2

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  2.2   Infrared spectroscopy

  The infrared spectra of complexes 1 and 2 show that the absorption peaks around 1 434~1 376 cm^-1 are due to C—C absorption vibration of the phenyl rings in diphosphine ligands. The absorption peaks around 3 450 cm^-1 are related to O—H bending vibration in methanol and the absorption peaks around 1 600 cm^-1 are put down to C=N bending vibration in diimine ligands. As for complex 2, the absorption peak at 2 096 cm^-1 is related to C≡N bending vibration of coordinated cyanogen, showing a red shift to normal cyanogen (about 2 200 cm^-1).

  2.3   Description of crystal structures

  Single - crystal X - ray diffraction analysis reveals that complex 1 crystallizes in the monoclinic crystal system with space group P₂₁/c. The asymmetric unit (Fig. 2) consists of one Cu(Ⅰ) cation, one dppp ligand and one Bphen ligand, forming a simple mononuclear heteroleptic complex. Cu(Ⅰ) ion, the metal center which adopts four - coordinated mode, coordinates with two P atoms from dppp and two N atoms from Bphen to form a distorted tetrahedral structure, which is comprised of the angels in a range of 81.10(11)° ~131.91(4)°. The Cu—N bond lengths (0.240 3(3) and 0.240 7(3) nm) and Cu—P bond lengths (0.220 6(1) and 0.225 1(1) nm) are normal for four-coordinated complexes. Complex 1 units form a 1D chain structure through four hydrogen bonds: O1—H1A…Cl1 (O1…Cl1 0.322 nm), C1—H1…Cl1 (C1…Cl1 0.369 nm), C2—H2…O1 (C2 …O1 0.325 nm) and C10—H10…Cl1 (C10…Cl1 0.358 nm) (Fig. 3, Table 3), and the parallel 1D chains form 2D network through three C—H… π interactions (Fig. 4, Table 4). Just like in the reported complexes^[22], C—H… π interactions display a fateful role in the structural orientation of complex 1.

  Figure 2

  

  Figure 2.  Molecular structure of complex 1

  All hydrogen atoms are omitted for clarity; Thermal ellipsoids are drawn at the 30% probability level

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  Figure 3

  

  Figure 3.  One-dimensional infinite chain of complex 1 formed through four hydrogen bonds

  Most of hydrogen atoms and a part of benzene rings are omitted for clarity

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  Table 3

  

  Table 3.  Hydrogen bond parameters of complexes 1 and 2

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  	D—H…A	d(H…A)/nm	d(D…A)/nm	∠DHA/(°)
  1	O1—H1A…Cl1	0.241	0.322 0(3)	170
  	C1—H1…Cl1	0.279	0.369 2(4)	162
  	C2—H2…O1	0.237	0.325 1(5)	157
  	C10—H10…Cl1	0.280	0.357 6(4)	141
  2	O1—H1…N3	0.199	0.275 0(7)	150
  	C30—H30B…O1	0.239	0.326 1(13)	149

  Figure 4

  

  Figure 4.  Two-dimensional net structure of complex 1

  Most of hydrogen atoms and benzene rings are omitted for clarity; Symmetry codes: ⁱ-1-x, -0.5+y, 0.5-z; ⁱⁱ 1+x, y, z; ⁱⁱⁱ-1+x, y, z

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  Table 4

  

  Table 4.  Intermolecular C—H…π interaction parameters of complex 1

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  C—H…Ring (i)	d(H…R) / nm	∠C—H…π / (°)	d(C…R) / nm
  C17—H17→R(1)i	0.295	156	0.381 6(4)
  C31—H31→R(2)ii	0.290	149	0.372 7(4)
  C50—H50→R(3)iii	0.280	142	0.357 4(4)
  R(1)=C46~C51, R(2)=C28~C33, R(3)=C19~c24; Symmetry codes: i-1-x, -0.5+y, 0.5-z; ii1+x, y, z; iii -1+x, y, z

  Complex 2 crystallizes in the monoclinic crystal system with space group P₂₁/c. Different from complex 1, complex 2 is a dinuclear hybrid complex with two metal centers. The symmetric unit (Fig. 5) is comprised of two Cu(Ⅰ) ions, two cyano groups, one dppp ligand and two dmp ligands. Each Cu(Ⅰ) ion is bonded to two N atoms from dmp ligand, one P atoms from dppp and one C atom from cyanogen to establish a distorted tetra- hedral geometry around the metal. Different from in complex 1, the dppp ligand in complex 2 acts as a typi- cal bridged ligand to connect two Cu ions. The geometry structure of one Cu center in the complex is totally same to the other, which is distorted tetrahedral configuration confirmed by the angles in a range of 80.52(18)° ~122.84(19)° and the bond length between 0.191 50(64) to 0.225 76(14) nm. Complex 2 units form a 1D chain structure through two hydrogen bonds: O1—H1…N3 (O1…N3 0.275 nm) and C30—H30B… O1 (C30…O1 0.326 nm). In this structure, two metha- nols form a dimer, acts as a bridge (Fig. 6, Table 3).

  Figure 5

  

  Figure 5.  Molecular structure of complex 2

  All hydrogen atoms are omitted for clarity; Thermal ellipsoids are drawn at the 30% probability level

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  Figure 6

  

  Figure 6.  One-dimensional infinite chain of complex 2

  Most of hydrogen atoms and a part of benzene rings are omitted for clarity

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  2.4   UV - Vis absorption spectra and fluorescence spectra

  The UV - Vis absorption spectra of complexes 1 and 2 are displayed in Fig. 7. All the measurements were carried out at room temperature. The absorption peak of complexes 1 and 2 between 250 to 325 nm can be assigned to π→π * and n→π* transitions of dppp, dmp and Bphen. The peak between 350 to 425 nm can be assigned to MLCT that participates in the genera- tion of the complexes′ fluorescence^[23-24]. The solid-state excitation and emission spectra of complexes 1 and 2 were measured at room temperature. Both 1 and 2 emitted orange light when they were excited under UV light. It was found that the emission peak was centered at 587 nm with λ_ex=372 nm for complex 1 and the maximum emission of complex 2 at 298 K was observed at 592 nm with λ_ex=395 nm (Fig. 8). The luminescent spec- tra show that the emission mechanism is MLCT, just like reported heteroleptic Cu complexes^[25]. The methyl of dmp can effectively reduce the distortion of configuration of center metal ion. Cyanogen coordinat- ing to copper has an impact on electrons transfer from metal to ligands. The distinction between the emission maxima of complexes 1 and 2 indicates that different li- gands and anions have an effect on the luminescence behavior of complex.

  Figure 7

  

  Figure 7.  UV-Vis absorption spectra of 1 and 2 in CH₂Cl₂ solution at 298 K

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  Figure 8

  

  Figure 8.  Emission spectra of 1 and 2 in solid state at room temperature

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  2.5   THz-TDS spectra

  THz-TDS can be used to distinguish and identify polar complexes due to the rotation and vibration of the dipoles in polar molecules that often make strong absorption peak in THz spectra^[26]. The THz spectra of 1, 2, dppp, Bphen and dmp were measured in a range of 0.2~2.8 THz (Fig. 9 and 10). These five compounds all have an intense impact on the THz spectra, generating many absorption peaks. The frequency of relevant peaks are listed: 0.22, 0.32, 0.43, 0.55, 0.66, 0.76, 0.88, 1.00, 1.10, 1.21, 1.32, 1.44, 1.55, 1.64, 1.73, 2.05, 2.31, 2.49, 2.59, 2.73 THz for dppp; 0.23, 0.32, 0.45, 0.60, 0.76, 0.94, 1.10, 1.31, 1.43, 1.69, 2.32, 2.53, 2.63, 2.80 THz for Bphen; 0.23, 0.41, 0.76, 1.05, 1.34, 1.46, 1.70, 2.22, 2.63 THz for dmp; 0.24, 0.32, 0.42, 0.56, 0.78, 0.91, 1.00, 1.12, 1.33, 1.44, 1.67, 1.86, 1.96, 2.08, 2.20, 2.32, 2.41, 2.59, 2.73 THz for 1; 0.23, 0.32, 0.47, 0.73, 1.50, 1.70, 1.87, 2.04, 2.20, 2.37, 2.49, 2.63, 2.75 THz for 2. By comparing the THz spectra of the ligands and complexes 1 and 2, we can discover that some peaks of the ligands moved or disappeared and some new peaks appeared for the complexes. These new peaks relate to the newly formed bonds and weak forces as well as crystal lattice vibration, leading to a big difference between the THz spectra of two complexes. The THz spectrum of complex 1 had more peaks than that of 2, probably because there are more weak forces in complex 1 than in complex 2. Therefore, THz spectra can be used to distinguish the complexes that have delicate difference.

  Figure 9

  

  Figure 9.  THz spectra of Bphen, dmp and dppp

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  Figure 10

  

  Figure 10.  THz spectra of complexes 1 and 2

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  3.   Conclusions

  Two novel heteroleptic Cu(Ⅰ) complexes, [Cu(dppp) (Bphen)]Cl·1.8CH₃OH (1) and [Cu₂(CN)₂ (dppp) (dmp)₂] ·2.5CH₃OH (2), have been synthesized and characterized by single - crystal X - ray diffraction, elemental analysis, IR, ¹H NMR and 31P NMR spectroscopy, fluorescence spectra and THz-TDS. Complex 1 is a mononuclear complex and complex 2 is a dinuclear complex. By weak forces, complex 1 forms a 2D network structure and complex 2 forms a 1D chain structure. Complex 2 had a stronger emission peak than complex 1. Both their emission peaks are derived from metal-to-ligand charge transfer (MLCT). Both the complexes show good stability in the air, which can be used in optical materials and luminescence research. THz - TDS provides useful information for researching the structure and properties of the compounds.

  
  
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  Scheme 1  Structures of the ligands

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  Figure 1  Thermogravimetric analysis of complexes 1 and 2

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  Scheme 2  Syntheses of complexes 1 and 2

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  Figure 2  Molecular structure of complex 1

  All hydrogen atoms are omitted for clarity; Thermal ellipsoids are drawn at the 30% probability level

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  Figure 3  One-dimensional infinite chain of complex 1 formed through four hydrogen bonds

  Most of hydrogen atoms and a part of benzene rings are omitted for clarity

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  Figure 4  Two-dimensional net structure of complex 1

  Most of hydrogen atoms and benzene rings are omitted for clarity; Symmetry codes: ⁱ-1-x, -0.5+y, 0.5-z; ⁱⁱ 1+x, y, z; ⁱⁱⁱ-1+x, y, z

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  Figure 5  Molecular structure of complex 2

  All hydrogen atoms are omitted for clarity; Thermal ellipsoids are drawn at the 30% probability level

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  Figure 6  One-dimensional infinite chain of complex 2

  Most of hydrogen atoms and a part of benzene rings are omitted for clarity

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  Figure 7  UV-Vis absorption spectra of 1 and 2 in CH₂Cl₂ solution at 298 K

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  Figure 8  Emission spectra of 1 and 2 in solid state at room temperature

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  Figure 9  THz spectra of Bphen, dmp and dppp

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  Figure 10  THz spectra of complexes 1 and 2

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  Table 1.  Crystallographic data of complexes 1 and 2

  Complex	1	2
  Formula	C52H46ClCuN2OP2	C59H58Cu2N6O2P2
  Formular weight	875.84	1 072.13
  T/K	103(2)	105(2)
  Crystal system	Monoclinic	Monoclinic
  Space group	P21	C2/c
  Crystal size/mm	0.35×0.35×0.4	0.08×0.55×0.6
  a/nm	1.173 13(5)	2.491 92(14)
  b/nm	1.942 58(6)	1.008 24(5)
  c/nm	2.108 79(8)	2.159 47(9)
  β/(°)	104.059(5)	102.636(5)
  V/nm3	4.661 8(3)	5.294 2(5)
  Z	4	4
  F(000)	1 824.0	2 232
  Goodness-of-fit on F2	0.983	1.087
  Rint	0.090 1	0.041 9
  R1 [I > 2σ(I)]a	0.059 7	0.065 9
  wR2 [I > 2σ(I)]b	0.106 9	0.156 2
  R1 (all data)a	0.101 5	0.083 7
  wR2 (all data)b	0.125 2	0.166 5
  aR1=∑(||Fo|-|Fc||)/∑|Fo|; bwR=[∑w(|Fo|2-|Fc|2)2/∑w(Fo2)]1/2.

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  Table 2.  Selected bond lengths (nm) and bond angles (°) for complexes 1 and 2

  1
  Cu1—P1	0.220 58(10)	Cu1—P2	0.225 08(10)	Cu1—N1	0.204 7(3)
  Cu1—N1	0.204 3(3)
  P1—Cu1—P1	103.91(4)	P1—Cu1—N1	119.71(8)	P1—Cu1—N2	131.28(8)
  P2—Cu1—N1	102.17(8)	P2—Cu1—N2	114.42(8)	N1—Cu1—N2	81.10(11)
  2
  Cu1—P1	0.225 76(14)	Cu1—C28	0.191 50(64)	Cu1—N1	0.210 31(43)
  Cu1—N2	0.210 24(51)
  P1—Cu1—C28	122.84(19)	P1—Cu1—N1	106.22(12)	P1—Cu1—N2	100.04(12)
  C28—Cu1—N1	118.0(2)	C28—Cu1—N2	120.52(23)	N1—Cu1—N2	80.52(18)

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  Table 3.  Hydrogen bond parameters of complexes 1 and 2

  	D—H…A	d(H…A)/nm	d(D…A)/nm	∠DHA/(°)
  1	O1—H1A…Cl1	0.241	0.322 0(3)	170
  	C1—H1…Cl1	0.279	0.369 2(4)	162
  	C2—H2…O1	0.237	0.325 1(5)	157
  	C10—H10…Cl1	0.280	0.357 6(4)	141
  2	O1—H1…N3	0.199	0.275 0(7)	150
  	C30—H30B…O1	0.239	0.326 1(13)	149

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  Table 4.  Intermolecular C—H…π interaction parameters of complex 1

  C—H…Ring (i)	d(H…R) / nm	∠C—H…π / (°)	d(C…R) / nm
  C17—H17→R(1)i	0.295	156	0.381 6(4)
  C31—H31→R(2)ii	0.290	149	0.372 7(4)
  C50—H50→R(3)iii	0.280	142	0.357 4(4)
  R(1)=C46~C51, R(2)=C28~C33, R(3)=C19~c24; Symmetry codes: i-1-x, -0.5+y, 0.5-z; ii1+x, y, z; iii -1+x, y, z

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