林森　李躍　崔洋哲　張彥茹　王夢秦　李中峰　金瓊花

(首都師范大學化學系，北京100048)

含雙(2-二苯基膦苯基)醚的Ag（Ⅰ）配合物的合成和表征

林森李躍崔洋哲張彥茹王夢秦李中峰金瓊花＊

(首都師范大學化學系，北京100048)

合成了2個含有雙膦配體的Ag（Ⅰ）配合物，分別是[Ag(DPEphos)(dppe)]2SO4(1)和[Ag(DPEphos)(SCN)]2·CH2Cl2(2)(DPEphos=雙(2-二苯基膦苯基)醚，dppe=雙(二苯基膦)乙烷)，并通過紅外光譜，核磁氫譜，元素分析，X射線單晶衍射及熒光光譜表征分析。通過熱重分析了2個配合物的熱穩(wěn)定性。結(jié)構(gòu)分析表明配合物1具有簡單的單核結(jié)構(gòu)，每個Ag和2個膦配體中的4個P原子螯合配位。配合物2具有雙核結(jié)構(gòu)，在配合物2中存在微弱的金屬與金屬間的作用。在Ag2S2環(huán)中，4個原子相互之間形成的內(nèi)角之和為360°，形成的環(huán)[-Ag-S-Ag-S-]是一個平行四邊形。熒光光譜顯示配合物中的發(fā)射峰主要來源于雙膦配體中的π-π*躍遷。熱重分析結(jié)果表明，在340℃附近，2個配合物開始分解，具有良好的穩(wěn)定性。

雙(2-二苯基膦苯基)醚；雙(二苯基膦)乙烷；Ag（Ⅰ）配合物；熒光；熱重分析

0　Introduction

Currently,an increasing interest in the design and synthesis of mono-and bi-nuclear complexes or clusters with group 11 metals(Cu,Ag,Au)has been attracted,notonly for their fascinating architectures[1-3], but also for the potential applications in antibacterial agents[4],organic lightemitting diodes[5]and catalysis[6-7]. Among these complexes,silver（Ⅰ）complexes with many commercially available bisphosphine ligands have been systematically investigated.

Bis(2-(diphenylphosphino)phenyl)ether(DPEphos, Scheme 1)has been extensively studied by Van Leeuwen and his co-workers[8]due to its good chelating capability and its catalytic utility in a variety of organic transformations[9].The tridentate nature of this ligand produces interesting coordination architectures. In view of this,considerable attention has been paid to the developmentsofthe metal-DPEphos complexes[10]. As closed-shell d10metal complexes,copper-DPEphos complexes have been extensively studied,but few silver complexes containing DPEphos were obtained. Besides,bis(diphenylphosphino)ethane(dppe)is usually used as bridging or chelating ligand in polymeric complex to form various coordination modes[11-12].

Scheme 1 Structures of ligands DPEphos and dppe

Following the earlierstudieson homolepticsilver（Ⅰ）compounds with bisphosphine ligands[10-13],we became naturally interested in extending our investigations to silver（Ⅰ）complexes with two kinds of bi-sphosphine ligands(Scheme 1).In this paper,we report the synthesis,structure characterization and photophysical properties of two silver（Ⅰ）complexes with DPEphos ligands[Ag(DPEphos)(dppe)]2SO4(1)and[Ag(DPEphos) (SCN)]2·CH2Cl2(2)(Scheme 2).They have been isolated and characterized by IR,single crystal X-ray diffraction,fluorescence and1H NMR spectroscopy.In particular,complex 2 shows metallophilic interactions in which metalmetal interactions are atypically shorter than the sum of their van der Waals radii.Sometimes, this may lead to enhanced photophysical properties as wellas stabilization ofmetalcomplexes[14-15].

Scheme 2 Routine of synthesis for complexes 1 and 2

1　Experimental

1.1Materials and measurements

All chemical reagents are commercially available and used without furthermore treatment.FT-IR spectra (KBr pellets)were measured on a Perkin-Elmer Infrared spectrometer.C,H and N elements analysis were carried out on an Elementar Vario MICRO CUBE(Germany)elemental analyzer.Roomtemperature fluorescence spectra were measured on F-4500 FL Spectrophotometer.1H NMR was recorded at room temperature with a Varian VNMRS 600MHz spectrometer.

1.2Synthesis of[Ag(DPEphos)(dppe)]2SO4(1)

Complex 1 was prepared at room temperature, using Ag2SO4(0.031 3 g,0.1 mmol),dppe(0.079 9 g, 0.2 mmol)and DPEphos(0.107 1 g,0.2 mmol)in a mixture of 5 mL CH2Cl2and 5 mL CH3OH.Yield: 65%.1H NMR(600 MHz,DMSO-d6,298 K):δ7.46～6.75(m,CHbenzene),2.47(d,CH2).IR data(KBr pellets, cm-1):3 420s,3 053m,1 638m,1 586w,1 481m,1 460 m,1 434s,1 258w,1 214m,1 095s,998w,871w,803w, 744s,695s,512m,476w.Element analysis Calcd.for C124H104Ag2O6P8S(%):C 68.08,H 4.76;Found(%):C 67.52,H 4.74.

1.3Synthesis of[Ag(DPEphos)(SCN)]2·CH2Cl2(2)

Complex 2 was prepared in a manner similar to thatdescribed for 1,using AgSCN(0.03 4 g,0.2 mmol) and DPEphos(0.107 0 g,0.2 mmol)in a mixture of 5 mL CH2Cl2and 5 mL CH3OH.Yield:18%.1H NMR (600 MHz,DMSO-d6,298 K):δ7.44～6.67(m,CHbenzene). IR data(KBr,cm-1):3 435w,2 090m,2 017w,1 619w, 1 478m,1 460m,1 433s,1 258w,1 222m,1 094w,798w, 745s,694s,541w,506w,471w.Anal.Elementanalysis Calcd.for C75H58Ag2Cl2N2O2P4S2(%):C 60.24,H 3.88, N 1.87;Found(%):C 61.38,H 4.08,N 2.08.

1.4Structure determination

Single crystals of the title complexes were mounted on a Bruker Smart 1000 CCD diffractometer equipped with a graphite-monochromated Mo Kα(λ= 0.071 073 nm)radiation.Semi-empirical absorption corrections were applied using SADABS program[16]. Allthe structures were solved by direct methods using SHELXS program of the SHELXTL-97 package and refined with SHELXL-97[17].Metal atom centers were located from the E-maps and other non-hydrogen atoms were located in successive difference Fourier syntheses.The final refinements were performed by full matrix least-squares methods with anisotropic thermal parameters for non-hydrogen atoms on F2. The hydrogen atoms were generated geometrically and refined with displacement parameters riding on the concerned atoms.Crystallographic data and experimental details for structural analysis are summarized in Table 1.Selected bond lengths and angles of 1～2 are given in Table 2.

CCDC:1416572,1;1416573,2.

Table 1 Crystallographic data for complexes 1～2

Table 2 Selected bond distances(nm)and bond angles(°)for complexes 1～2

2　Results and discussion

2.1Synthesis of the single crystal

Two Ag（Ⅰ）complexes are air-stable,soluble in common polar solvents such as methanol, dichloromethane,acetonitrile.We have synthesized a series of silver（Ⅰ）complexes with DPEphos and dppe ligands including the complex[Ag(DPEphos)(dppe)] BF4[13].In view ofourinterestin the influence ofanions, we have reported a few metal complexes with sulfate or thiocyanate anion.In literature[18-20],there are different coordination modes of sulfate anion,which can influence the structure of the complexes. However,complex 1 with free sulfate anion was obtained by reactions in the mixed solution of CH3OH and CH2Cl2.In addition,thiocyanate can act as a highly versatile bi-dentate ligand with a polarizableπ system to form the coordination mode(μ-NCS)[21].We obtained sulfur-bridged binuclear cluster 2 by the reaction of AgSCN with DPEphos in the same molar ratio in the absence of dppe.Also all the complexes are stable in air and can be stored for long term.

2.2Infrared spectroscopy and1H NMR spectroscopy

The infrared spectra of complexes 1～2 show that the absorption peaks around 1 434 cm-1are due to CC stretch vibration of the phenyl rings and the middle absorption peaks around 3 052 cm-1are caused by CH vibration of the phenyl rings.The absorption of the S-O stretch vibration is around 1 214 cm-1.And the band around 2 090 cm-1for 2 is assigned to thiocyanate(SCN-).

The1H NMR spectra of complexes 1～2 exhibit signals(multiple peaks)atδ7.4～6.7,which can be attributed to protons from the benzene rings of the diphosphine ligands.In complex 1,the triplet signal ofthe methylene group ofdppe is atδ2.47.

2.3Description of the crystal structure

Complex 1 is simple mono-nuclear complex with Ag2SO4,dppe ligand and DPEphos ligand.The molecule structure of complex 1 is shown in Fig.1. Each Ag（Ⅰ）atom is four-coordinated and attached to four phosphorus atoms(two from a chelating dppe ligand and two from a chelating DPEphos ligand). Their bond lengths are close to those in analogous complexes[13].The geometry around each metal center is distorted tetrahedral as is evident from the angles in the range of 81.83(7)°～125.19(6)°.In complex 1, the average bite angle of the DPEphos ligand is 104.17(6)°,which is larger than its natural bite angle (βn)[8].However,they are much smaller than that in [Ag(κ2-P,P′-DPEphos)(2,2′-bpy)][OTf](113.51(7)°)and [Ag(DPEphos)(py2SH)2]NO3(112.20(2)°)[22-23],which is attributed to the influence of co-ligand.The C-H…π (0.262 nm and 0.287 nm)weaker interactions stabilize the complex.

Fig.1 Molecular structure of complex 1

Single-crystal X-ray diffraction analysis reveals that complex 2 crystallizes in the triclinic system with space group P1.It consists of inversion symmetric dimers with a diamond-shaped Ag2S2group at the center(Fig.2).Complex 2 is a bi-nuclear cluster of Ag（Ⅰ）where the Ag…Ag distance(0.331(5)nm) exceeds the sum of two covalent radii(four coordinated univalent silver)(0.292 nm)but is shorter than the sum of two van der Waals radius of silver atoms(0.344 nm),to some extent,indicating weak argentophilic interactions.The sum of the internal angles of the four-member ring[-Ag-S-Ag-S-]in the Ag2S2core is 360°,demonstrating that the ring is a parallelogram.Two adjacent[Ag(DPEphos)(SCN)]units are bridged by two S atoms with 50%occupancy to form a dimer,just like Ag2I2(DPEphos)2[24].And the average bite of the DPEphos ligand is 113.24(3)°in complex 2,which is smaller than the same bite in Ag2I2(DPEphos)2.

Fig.2 Molecular structure of complex 2

2.4Thermogravimetric analysis

The complexes 1～2 have been analyzed by TGA. From Fig.3,we can see that the complex 2 decomposes by two steps,and complex 1 decomposes by one step.

Fig.3 TGA curves of complexes 1～2

The initial weight loss of complex 1 is at 340℃, then complex 1 decomposes to Ag rapidly from 340 to 450℃.Complex 2 starts to decompose at175℃,which is attributed to the weight loss of the dichloromethane molecule from the crystallattice.The low decomposing temperature of 2 is due to the low boiling point of dichloromethane.Complex 2 decomposes into Ag2S rapidly from 400 to 470℃.The finalweightlossdata(%) of the two complexes are listed as following:complex 1:94.99%(Calcd.95.06%);complex 2:83.09%(Calcd. 83.41%).

The order of the stability is as following:complex 1＞complex 2.The great stability shown by the two complexes may be caused by the way of chelating through P atoms.

2.5Description of luminescent

The luminescent excitation and emission spectra of complexes 1～2 are measured in the solid state at room temperature(Fig.4).The ligand dppe exhibitsfluorescence signal at 434 nm with an excitation maximum at 310 nm[25].In the solid fluorescence emission spectrum of DPEphos ligand,the emission peak is found at453 nm(λex=317 nm)[13].In the fluorescence emission spectra ofcomplexes 1～2,the emission peaks are found at434 nm(λex=370 nm)for 1,443 nm(λex= 351 nm)for 2,respectively.The similarity of the emission spectra of complexes 1～2 and that of dppe or DPEphos ligand indicates that the origin of these emissions all involves emissive state derived from ligand-centred(π-π*)transition.

Fig.4 Solid-state excitation and emission spectra of 1～2 at 298 K

3　Conclusions

Two new Ag（Ⅰ）complexes ofphosphine-containing ligands(DPEphos or dppe)have been synthesized and characterized by elemental analysis,IR,X-ray diffraction,fluorescence,1H NMR,spectroscopy.Structure analysis shows complex 1 is of simple mono-nuclear structures,each silver atom is chelated by a dppe ligand and a DPEphos ligand.Complex 2 is a binuclear cluster of Ag（Ⅰ）,indicating weak argentophilic interactions.The luminescent spectra show that the origin of these emissions involves emissive state derived from ligand-centered(π-π*)transition.The great stability shown by the two complexes may be caused by the way of chelating through phosphine atoms.The great stability can be used in optical materialand other applications.

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Syntheses and Characterization of Silver（Ⅰ）Complexes of Bis(2-(diphenylphosphino)phenyl)ether

LIN Sen LI Yue CUIYang-Zhe ZHANG Yan-Ru WANG Meng-Qin LIZhong-Feng JIN Qiong-Hua＊
(Department of Chemistry,Capital Normal University,Beijing 100048,China)

Two novel silver（Ⅰ）complexes[Ag(DPEphos)(dppe)]2SO4(1)and[Ag(DPEphos)(SCN)]2·CH2Cl2(2) (DPEphos=bis(2-(diphenylphosphino)phenyl)ether,dppe=bis(diphenylphosphino)ethane)have been synthesized and characterized by IR,1H NMR spectroscopy,elemental analysis,single-crystal X-ray diffraction and fluorescence spectra.Structure analysis shows that complex 1 has simple mono-nuclear structures,and each silver atom is chelated by four phosphines.Complex 2 has a bi-nuclear cluster of Ag（Ⅰ）,showing weak argentophilic interactions.The sum of the internal angles of the four-member ring[-Ag-S-Ag-S-]in the Ag2S2core is 360°, demonstrating that the ring is a parallelogram.The luminescent spectra of 1～2 are studied,which show that the emission peaks are assigned to theπ-π*transitions of the diphosphine ligands.Thermogravimetric analysis shows that two complexes begin to decompose ataround 340℃,indicating their strong stability.CCDC:1416572, 1;1416573,2.

bis(2-(diphenylphosphino)phenyl)ether;bis(diphenylphosphino)ethane;silver（Ⅰ）complex;fluorescence;TGA

O614.122

A

1001-4861(2016)12-2165-07

10.11862/CJIC.2016.273

2016-06-12。收修改稿日期：2016-10-19。

國家自然科學基金(No.21171119，81573832)、863國家高技術(shù)研究發(fā)展計劃(No.2012AA063201)、北京教育委員會基金(No.KM201210028020)、北京市優(yōu)秀人才項目(No.2010D005016000002)和北京市自然科學基金(No.7122015)資助。

＊通信聯(lián)系人。E-mail：jinqh@cnu.edu.cn；會員登記號：S06N3669M1105。