Synthesis and crystal structure of {[(C5H9C5H4)Er(THF)]2(μ2-Cl)3(μ3-Cl)2Na(THF)2} · THF

Synthesis and crystal structure of {[(C5H9C5H4)Er(THF)]2(μ2-Cl)3(μ3-Cl)2Na(THF)2} · THF

Polyhedron Vol. I I, No. 22, pp. 287s2876, Printed in Great Britain 1992 0 0277-5387/92 $5.00+ .m 1992 Pergamon Press Ltd SYNTHESIS AND CRYSTAL STR...

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Polyhedron Vol. I I, No. 22, pp. 287s2876, Printed in Great Britain

1992 0

0277-5387/92 $5.00+ .m 1992 Pergamon Press Ltd

SYNTHESIS AND CRYSTAL STRUCTURE OF

{I(C,H,C,H3Er(THF)I,(lc,-Cl),Or,-Cl),Na~~)~~ ‘mm’ l

JIZHU

JIN, SONGCHUN

JIN, ZHONGSHENG

JIN and WENQI CHEN”

Changchun Institute of Applied Chemistry, Academia Sinica, Changchun 130022, P.R.C. (Received 18 March 1992 ; accepted 17 July 1992)

Abstract-The reaction of ErCl, with one equivalent of CSHgC5H4Na generates the complex ([(CgHgC5H4)Er(THF)]2(~2-C1)3(~~-C1)2Na(THF)2} . THF, which crystallizes from hexane/THF. The X-ray crystal structure determination shows that each erbium is surrounded by one CSH9CSH4 ligand, two p3-Cl, two p2-C1 and one THF in a distorted octahedral arrangement.

method, and sodium using a Shimadium 646 atomic Since 1980, the synthesis and molecular structure of bis(substituted cyclopentadienyl)lanthanide de- absorption spectrometer. The IR spectra were recorded on a Diglab FTS-20E spectrometer as KBr rivatives have been widely studied. I-6 However, few reports on the synthesis and molecular struc- pellets. ture of mono(cyclopentadieny1 or substituted derivatives have Preparation of ([(C5HgCSH4)Er(THF)12(p2-CI), cyclopentadienyl)lanthanoid appeared. 7-‘4 Only six of these compounds, (p3-C1)2Na(THF)2) . THF (CgH,)LnC12(THF), (Ln = Nd,’ Er,” Yb”), (CSMeS)Cc12(THF)3,‘2 ~(DME)3I{K[(C,Me,Yb), To a slurry of ErCl 3 in THF (15 cm 3, was slowly added a solution of CSHgC5H4Na (mol ratio 1: 1) WWMEh12}‘3 and {Na(p2-THF)[(CSMe,)Gd (THF)]2(~1-C1)3(~3-C1)2}2 . 6THF,14 have been in THF at -78°C with stirring. The mixture was characterized by X-ray crystallography. These allowed to warm to room temperature and stirred for 24 h. After centrifugation the solvent was evapstructures are either monomeric or oligomeric. No compound in which the structure is a orated in vucuo and Et,0 (20 cm’) was added to the residue and stirred for 12 h. The solution was dimer was reported. We have now synthesized the title compound and determined its crystal centrifuged and the solvent was removed in vacua to give a powder which was dissolved in THF and structure, which is found to be dimeric. We report here the details of the synthesis and crystal struc- hexane. Pink crystals (50.3%) were formed once the solution was cooled to -20°C. Found : Er, 30.6 ; ture of ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Cl, 15.9; Na, 2.4. Calc. for Er2NaC15C36H5804: Na(THF),) . THF (C5HgCSH4 = cyclo-pentylEr, 30.72 ; Cl, 16.28 ; Na, 2.11. IR(KBr) : 3065(w), cyclopentadienyl). 2960(s), 2865(s), 1645(s), 1585(m), 1450(m), 1370(w), 1345(w), 1180(w), 1055(m), 1010(s), EXPERIMENTAL 945(w), 910(m), 865(s), 835(s), 780(s), 675(m), 520(m), 470(w) cm- ‘. All manipulations were performed using Schlenk techniques under dry, oxygen-free nitrogen. The solvents were treated with NaOH, refluxed on X-ray crystallography sodium strips and distilled under nitrogen before Because the crystals contain THF solvent in the use. lattice, they readily deteriorated at ambient temThe analyses of lanthanide metal and chlorine perature. Many attempts were made to obtain a were accomplished using direct complexometric single crystal suitable for data collection. A pink titrations with disodium EDTA using the Volhard crystal of dimensions 0.32 x 0.24 x 0.4 mm was finally selected and kept in a stream of cold nitrogen * Author to whom correspondence should be addressed. for measurement.

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Table 1. Crystal data Compound Molecular weight Crystal system Space group Cell constants a (A) b (8) c (A) B (“) V(W’) Z R (g cm-‘) p (MO-K,) (cm- ‘) F(OO0) R Rw

C 36H 580 4Cl,NaEr, 1089.63 Monoclinic CVC 17.539(4) 11.123(3) 24.913(6) 90.78(2) 4860(2) 4 1.49 38.7 2152 0.075 0.075

Fig. 1. Molecular structure of the title compound.

The unit cell parameters were determined and intensity data were collected on a Nicolet R3m/E four-circle diffractometer equipped with an LT-1 low-temperature device at about -70°C using graphite monochromated MO-K, radiation (A = 0.71069 A). The o scan mode was utilized with a fixed scan speed of 7” min ’ and a scan width of 1.2” in the range 3” < 28 < 48”. A total of 4031 reflections were collected, of which 2345 with Z > 30(Z) were used in the final refinement. A standard reflection was measured every 70 reflections during data collection, but no significant variation in intensity was observed. The intensities were corrected for Lorentz and polarization, but not for absorption effects. The structure was solved by Patterson and Fourier techniques. The atomic coordinates and anisotropic temperature factors for all non-hydrogen atoms except for those of interstitial THF were refined by block-diagonal least-squares. The coordinates of interstitial THF could not be determined even when the lower symmetry space group Cc was used. The

coordinates of the hydrogen atoms were added according to theoretical models. The refinement finally converged to R = 0.075 and a maximum

shift/error ratio of 0.073. All calculations were carried out with an Eclipse S/140 computer by a SHELXTL program system. No contribution from atoms of the strongly disordered THF were included. The crystal data are shown in Table 1, selected bond lengths and angles are given in Tables 2 and 3 and the molecular structure is shown in Fig. 1.

RESULTS

AND DISCUSSION

Synthesis ErC13 reacts with CSH9C5H4Na (mole ratio 1: 1) in THF at room temperature to give {[(CSHgC5H4) Er(THF)],(~L,-C1)3(~3-C1)2Na(THF)2}, according to eq. (1) : THF

2ErC13+2CgH9C5H4NaTable 2. Selected bond lengths (A) Er-Era Er-Cl( 1) Er-Cl(3) Er-O( 1) Er-C( 12) Er-C( 14) Er--C(ring) Na-Cl(2) Na-Cl(2a) Na-O(2)

3.876(2) 2.744(6) 2.616(6) 2.339(15) 2.648(23) 2.654(25) av. 2.637 2.838( 11) 2.838(11) 2.343(22)

Er-Na Er-Cl(2) Er-Cl(2a) Er-C(Il) Er-C( 13) Er-C( 15) Er-Cp’ ” Na-Cl(3) Na-Cl(3a)

3.781 2.675(6) 2.844(5) 2.649(21) 2.636(26) 2.597(22) 2.344 2.836(7) 2.836(7)

’ Cp’ indicates the centroid of C( 11) to C( 15).

([(CSH9CSH4>ErCrHF11*012-C1>,013-C1)2Na(THF +NaCl

(1)

0

This complex is soluble in THF, DME, Et20 and toluene, but not in hexane. The elemental analyses are consistent with the formula for I, and the IR spectra gave absorption

bands for the.cyclopentyl ring at 2960, 2865 and 1450 cm-‘, cyclopentadienyl ring at 1010 cm-‘, THF molecule at 1055 and 910 cm-‘, and Er-Cl at 470 cm- ‘, respectively.

([(CSH,CSH4)Er(THF)I*(~*-Cl)3(~3-Cl),Na(THF),} -THF

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Table 3. Selected bond angles (“) l)---Er-Cl(2) Cl(l)-Er-Cl(3) Cl(I)---Er-Cp C1(2)--Er-O( 1) Cl(2)--Er-Cp’ C1(3)--Er-Cp’ 0( l)-Er-Cp’ C1(2a)-Er-Cp’ C1(2)---Na-O(2) C1(2)-Na-Cl(3a) C](3)---Na-O(2) C](3)-Na-Cl(3a) O(2)---Na--0(2a) Er-U(2)-Era Era-C](2)-Na

Cl(

77.2(1) 151.2(2) 101.4 150.5(4) 106.4 106.0 102.6 174.6 95.8(5) 75.3(3) 98.3(6) 148.4(5) 94.9(11) 89.2(2) 83.4(2)

Crystal structure

The X-ray crystal structure determination shows that the molecule is a dimer and the dimer unit has two-fold symmetry. Each erbium atom is coordinated to one ~J’-C~H~C~H~group, one oxygen atom of THF, two pL1-Cland two ~~-cl, and the geometry around the erbium is distorted octahedral. Two erbium atoms and one sodium atom form an approximately equilateral triangle, with distances Er-Na 3.781 and Er-Era 3.786 A. Three chloride atoms bridge the edges of the triangle, with angles Er-Cl(l)-Era 89.9”, Er-C1(3)-Na 87.7”, Era-C1(3a)-Na 87.7”, while two additional chlorine atoms cap the Er-Era-Na fragment on each side in a ps,-fashion. The Er-C(ring) distances range from 2.597(22) to 2.654(25) and average 2.637 A, which is comparable to 2.601 8, in [(CgH&5H4)2ErCl]z’5 and 2.730 8, in [(CgH9CSH4)2SmC1(THF)]2,‘S if the different atomic radius of samarium is considered. Subtracting the ionic radius of eight-coordinate Er3+ (1.004 A)16 from the average Er-C bond distance of the title compound (2.637 A) gives 1.633 A as the effective “ionic radius” of the cyclopentylcyclopentadienyl ligand. Values of 1.633 8, can be calculated for {Na&-THF)[(C ,Me 5)

Gd(THF)I,(~,-Cl),(~,-Cl),}2.6-m~. The Er-p2-C1 distances can be divided into two groups : the Er-~2-C1( 1) bond which is connected to the other erbium atom is 2.744(6) A, while Er-p2-Cl(3) [2.616(6) A] which connects to the sodium atom is shorter. Similar behaviour has been reported for the Ln-Cl distance in complexes with an Ln-(p-Cl)-Ln or an Ln-(p-Cl)-M unit. ’ 33’ 4 The average bond length of Er-p,-Cl(2.760 A) is longer than that of Er-p2-C1(1)(2.744 A). This is

Cl( l)-Erxl(2a) Cl(l)-Er-O( 1) C1(2)-Erxl(3) C1(2)-Er-Cl(2a) C1(3)--Er-O( I) C&+---Er--c@d)

O(I)-Er-Cl(2a) C1(2)--Na-Cl(3) C1(2)-Na-Cl(2a) C1(2t_Na-O(2a) C1(3)-Na-Cl(2a) C1(3)-Na-O(2a) Er-CI( 1)--Era Er-C1(2)-Na Er-C1(3)---Na

74.5(1) 92.4(4) 86.6(2) 76.3(2) 90.2(4) 78.7(2) 74.4(4) 79.6(3) 73.9(4) 168.6(6) 75.3(3) 102.9(7) 89.9(2) 86.5(2) 87.7(3)

usual since increased bridging tends to give longer bond lengths.‘7v’s However, the bond length of Na-p2-Cl(3) (2.836 A) is equal to that of Na-pr Cl(2) (2.838 A). The bond length of Er-p3-C1(2) [2.675(6) A] is shorter than that of Er-p,-Cl(2a) [2.844(5) A]. This is due to the existence of the THF bonded to erbium. This phenomenon has been observed for {Na~2-THF)[(C,Me,>cd(THFII,0LTC1>,013CQ2j2. 6THF14 and [(C,H5)2NdC1(THF)]2.‘g The bond angle of 0( l)---Er-Cl(2) (150.5”) is much bigger than that of O(l)-Er-Cl(2a) (74.4”). The maximum deviation of the ring carbon atoms from their mean planes [C(l l)-C(15), C( 1la)-C( 15a)] is 0.020 A. The dihedral angle of the two planes is 128. 6”.

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