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Copper Complexes with the Ligand [Cp2MoH2]Henri Brunner1’*, Manfred Muschiol3, Thomas Neuhierl3, Bernhard Nuberba Institut für Anorganische Chemie, Universität Regensburg, D-93040 Regensburg, Germany b Anorganisch-Chemisches Institut der Universität Heidelberg, D-69120 Heidelberg, Germany

Z. Naturforsch. 54 b, 337-340 (1999); received September 25, 1998Copper, Molybdenum, X-Ray Data

The reaction of CuCl with [CP2M0H2] yields the complex [Cu(Cp2MoH2)2Cl]. An X-ray structure analysis shows that the coordination of the copper(I) ion by two [CP2M0H2] lig­ands and the chloride ion is pseudo-trigonal planar. The hydride ligands were located by using difference Fourier methods. A manifold of reactions took place when an aqueous so­lution of CUSO4 was treated with a solution of [Cp2M oH2] in dichloromethane in a 1:2 molar ratio. The X-ray structure analysis established a polymeric structure of the complex [Cu(Cp2MoH2)2Cu(Cp2MoH2)S0 4 ]„ with two different copper centers.

The complexes [CP2M0 H2] [1] and [CP2W H2 ] [1] each contain three low-lying molecular orbitals between the two bent cyclopentadienyl rings [2], The two outer orbitals are used to bind the a-bonded hydride ligands, the orbital in the middle contains a lone pair of electrons. In silver(I) complexes the ligands [CP2M0 H2] and [CP2W H 2] expose two hy­dride ligands towards the coordination center. X-ray structure analyses showed a great variety o f silver halide complexes with the ligand [CP2 M0 H2] [3 ,4], The reaction of [Cu(NCMe)4 ]PFö with [CP2MH2], M = Mo, W, in a molar ratio o f 1:2 yielded the complexes [Cu(Cp2 MH2)2]PF6 [5]. An X-ray struc­ture analysis of [Cu(Cp2MoH2)2 ]PFö H2O was car­ried out [5]. There are two independent cations [Cu(Cp2MoH2)2]+ in which the Mo-Cu-Mo units are arranged linearly (angle Mo-Cu-Mo 176.2 and 177.6°). The average Mo-H distance is 1.67(4) A and the average Cu-H distance is 1.68(6) A. The reaction of Cul with [CP2M0 H2 ] gave the dimeric complex [Cu(Cp2MoH2)I]2 A [6]. The compound [Cu(Cp2MoH2)2] CuCl2 B was formed in the reac­tion of copper(II) chloride with [CP2M0 H2] [6, 7]. Two [CP2M0 H2] units are bound to one copper cen­ter. There is an additional interaction between CuCl2

and two of the hydride ligands. The structures o f A and B are depicted in Scheme 1.

Here we describe the crystal structures o f the complexes [Cu(Cp2 MoH2)2Cl] and [Cu(Cp2 MoH2 )2Cu(Cp2 MoH2 )S 0 4 ]n ■

Reprint requests to Prof. Dr. H. Brunner.

/ N / H\ y Hv / H\C ^ M o C p 2 Cp2Mq^ ^ u s^ ^ M o C p 2

Cl^ N n

Scheme 1. Structures of [Cu(CptMoH->)I]t A and [Cu(Cp2MoH2)2]CuCl2 B.

Results and Discussion

The reaction of CuCl, suspended in water, with [CP2M 0 H2], dissolved in dichloromethane, yielded the complex [Cu(Cp2MoH2)2Cl]. The ’H NMR spectrum of the product in dö-acetone showed a triplet at 6 = 5.10 for the Cp ligands and a broad sin­glet at <5 = -10 .7 for the hydride ligands. Compared to [CP2 M0 H2] the Cp signal is shifted 0.53 ppm to lower field, whereas the hydride resonance expe­riences a shift o f 1.37 ppm to higher field. Crys­tals o f [Cu(Cp2MoH2)2Cl] suitable for an X-ray structure analysis were obtained from a mixture of dichloromethane and toluene. Details o f the data collection and structure refinement are given in Ta­ble I. Selected bond distances and angles are listed in Table II. Fig. 1 shows that two [CP2M 0 H2 ] lig­ands and one chloride ion are coordinated to the copper(I) center in a trigonal planar fashion (sum of bond angles 360°).

The M ol-C ul-M o2 angle is 134°. The Cp rings at the two Mo centers adopt a twisted confor­mation similar to that in the corresponding Ag

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338 H. Brunner et al. ■ Copper Complexes with the Ligand [CP2 M0 H2 ]

Table I. Summary of crystal data, data collection11 and structure refinement.

[Cu(Cp2MoH2)2Cl]b [Cu(Cp2MoH2)2Cu(Cp2MoH2)S 04]c

Elemental formula C20H24CICUM02 CwH36Cu2M o30 4SM 555.29 907.58Crystal system rhombic monoclinicSpace group C2v/5, Pca2, (No 29) C2h/5, P 2 |/a (No 14)Crystal colour, shape yellow prisms red brown “arrowheads”Crystal size (mm3) 0 .25x0.30x0.35 0.03x0 .50x0 .80«(A ) 15.380(6) 15.428(5)b(A) 11.016(6) 10.838(3)c (A) 11.280(5) 16.901(6)

# .,7 (°) 90, 90, 90 90, 97.51(3), 90V (A ) 1911(1) 2802(2)Z 4 4Density (g cm -3 ) 1.93 2.15F(000) 1096 1792p (mm-1 ) 2.53 2.91h,k,l ranges Oto 23 ,0 to 16 ,-17 to 17 -21 to 21, Oto 15, Oto 2320 Range (°) 3 .0 -62 .0 3 .0 -57 .5Total no. of unique reflections 6087 6976No. of observed reflections, I > 2.5 a\ 4737 4812Min, max transmission factors No. of reflections, 20 range (°) for

0.90, 1.00 0.35, 1.00

empirical absorption correction 8, 10.0 < 2 0 < 48 .0 8, 6.0 <20 < 40.0No. of least-squares parameters 217 381shift/esd-max 0.007 0.004^Pm\x\i -^Pmax (e A ) Rd

-1.00, 1.06 -0.94, 1.050.042 0.047

r J 0.035 0.040Goodness of fit 5*1 1.60 1.86

a SYNTEX R3 diffractometer: Mo-KQ radiation (A = 0.71073 A), 293 K; b d R = I |IF0I - IFJI / 1 IF 0I, Rn = I jlFol - IFJI - 1/2 and p = total number of parameters refined.

direct method; c Patterson-Fourier; , S = [Lw(F02 - F 2)2!{n - p)]]/2, where n = number of reflections

Table II. Selected bond lengths and angles of [Cu(Cp2MoH2)2Cl]; estimated standard deviations are shown in parentheses.

M ol-C ulMo2-CulC ul-C ll

2.859(2)2.835(2)2.339(2)

M ol-Cul-M o2 M ol-C ul-C ll M o2-Cul-Cll

134.0(1)111.8(1)114.2(1)

complexes [4].C pl and Cp3 form an angle of 45.3°, Cp2 and Cp4 an angle of 48.8°. The dihedral angles ring centroid-Mo-Cu-Cl differ considerably. Cp2- M ol-C u l-C ll is 5.8°, whereas Cp4-M o2-Cul-Cll is 55.2°. The distance H8-C11 is 2.85 A and the an­gle C8-H8-C11 is 114.8°. Thus, a weak hydrogen bond between the chloride ion and the hydrogen atom H8 of the cyclopentadienyl ring could stabi­lize the arrangement of Cp2 in the crystal [7, 8].

The positions of the hydride ligands HI A, H1B. H2A and H2B were determined by difference Fourier methods. The two rhombs formed by Mo,

Fig. 1. ORTEP plot of the structure of [Cu(Cp2MoH2)2Cl] with thermal ellipsoids at the 50% probability level.

the two hydride ligands and Cu are nearly coplanar (dihedral angle M ol-H lB -C ul-H 2A = 5.6°, Mo2- H1A-Cul-H2B = 7.6°). The H-Mo-H angles are 70.7° and 67.1°, respectively. The Mo-H distances

H. Brunner et al. • Copper Complexes with the Ligand [CP2 M0 H2 ] 339

Table III. Selected bond lengths and angles of [Cu(Cp2MoH2)2Cu(Cp2MoH2)S0 4 ]; estimated standard deviations are shown in parentheses.

M ol-Cu2 2.752(1) M ol-Cu2-Culb 117.3(1)Mo2-Cul 2.779(1) Culb-Cu2-01 120.9(2)Mo3-Cul 2.830(1) M ol-Cu2-01 120.9(2)Cul-Cu2a 2.775(2) Mo2-Cul-Mo3 143.5(1)C u l-04 2.194(4)Cu2-01 1.989(59

Fig. 2. Chain structure of the complex [Cu(Cp2MoH2)2- Cu(Cp2MoH2)S0 4 ]„. The connection of the Cu2 clusters by the SO4 tetrahedra is shown. The hydrogen atoms and the numbering scheme were omitted for clarity.

lie between 1.63 and 1.76 A. The shortest Cu-H distance is 1.69 and the longest 1.78 A.

A manifold of reactions took place when an aque­ous solution of C uS04 was treated with a solution of [CP2M0 H2] in dichloromethane in a 1:2 mo­lar ratio. In the FD mass spectrum of the prod­uct the peaks of the cations [Cu(Cp2MoH2)2 ]+ and [Cp2M oS04r + could be detected. From a mixture of dichloromethane/thf and methanol red brown crystals were obtained in low yield. The X-ray structure analysis established a polymeric struc­ture of this product. Details of the data collection and structure refinement are given in Table I. Se­lected bond distances and angles are listed in Ta­ble III. In Fig. 2 the chain structure of the com­plex is shown. Fig. 3 displays the monomer unit [Cu(Cp2MoH2)2Cu(Cp2M oH2)S04].

There are two different copper centers in the unit [Cu(Cp2MoH2)2Cu(Cp2MoH2)S04]. Cul is coordinated by Cu2a, the oxygen atom 0 4 and two [CP2M0 H2J ligands with the metal centers Mo2 and Mo3, whereas Cu2 is surrounded by Culb, 01 and one [CP2M0 H2 ] ligand with the metal center M ol (Fig. 3). The dihedral angle Culb-C u2-M ol-01 is 10.1°. There is a short C ul- Cu2a distance of 2.77 A [9]. The CU2 clusters are connected by S 0 4 tetrahedra (average S-O dis­tance 1.46 A). Thus, a chain structure is formed

Fig. 3. Crystal structure of the monomer unit [Cu(Cp2- MoH2)2Cu(Cp2MoH2)S04]. The arrows indicate the con­nections to the next neighbors within the chain.

with different Cu-O distances (C ul-0 4 2.19 A, Cu2-01 1.99 A).

The positions of the hydride ligands between Mo and Cu were determined by the difference Fourier method. The Mo-H distances lie between 1.58 and 1.77 A. The shortest Cu-H distance is 1.64 and the longest 2.08 A. The H-Mo-H angles range from 75.1° to 87.6°. The H-Cu-H angles are a little smaller (65.1° and 74.7°).

Three squares are formed by Mo, Cu and two hydride ligands. The two rhombs M ol-H211-Cu2- H 212 (dihedral angle 9.2°) and M o3-H31 -Cu 1-H32 (dihedral angle 9.8°) are nearly coplanar. The hy­drogen atom H 112 has a short distance to three met- all centers (Mo2-H112 1.77 A, Cul-H I 12 1.92 A and Cu2a-Hl 12 1.87 A). The formation of this hy­drogen bridge causes a strong tilt of HI 12 from the plane M o2-Hl 11-Cul (dihedral angle M o2-Hl 11- C ul-H l 12 115.2°).

Experimental

All reactions were carried out under an atmosphere of dry nitrogen with standard Schlenk techniques. The synthesis of [CP2M0H2] was described in reference [1]. Field desorption mass spectra were obtained from solu­tions of the compounds in dichloromethane on a Finnigan MAT 95 spectrometer. 1H NMR spectra were recorded on a Bruker ARX 400 instrument. Both X-ray structure anal­yses were recorded on a Syntex R3 diffractometer with Mo-Kq radiation at T - 293 K. The structures were solved by using the SHELXTL Plus Program (release 4.2/800), PC Version. Further details of the crystal structure in­vestigations may be obtained from the Fachinformations- zentrum Karlsruhe, D-76344 Eggenstein-Leopoldshafen (Germany) on quoting the depository CSD numbers given in each case.

340 H. Brunner et al. ■ Copper Complexes with the Ligand [CP2 M0 H2 ]

[Cu(Cp2MoH2 )2 Cl]: CuCl (49.4 mg, 0.50 mmol) was suspended in 10 ml of water. A solution o f [CP2M0 H2] (228 mg, 1.00 mmol) was added. The mixture was stirred for 1 h. The organic layer was separated. The solvent was removed and the yellow residue was washed with ether (yield: 108 mg (0.21 mmol, 42%)). Crystals suitable for X-ray structure analysis were obtained from a mixture o f CH2CI2 and toluene. CSD 410184.

'H NMR (400 MHz, d6-acetone): 6 = 5.10 (t, V HH =0.7 Hz, 5H, t]5-C5H5), -10 .7 (br s, 1H M o//). FD- MS: m/z (%): 519 ( 12) [Cu(Cp2MoH2)2]+, 230 ( 1 00) [Cp2M oH2]*+.

C2()Ho4C1CuMoi (555.29)Calcd C 43.26 H 4.36 %,Found C 42.92 H 4.77 %.

Reaction of CUSO4 5 H2 O with [CP2M0 H2]:CUSO4 5 H2O (286 mg, 0.50 mmol) was dissolved in 10 ml o f water. A solution o f [CP2M0 H2] (228 mg,1.00 mmol) was added. The mixture was stirred for 1 h. The organic layer was separated. The solvent was re­moved and the yellow residue was washed with ether. Crystals suitable for X-ray structure analysis were ob­tained from a mixture o f CH2C12/THF and methanol. CSD 410185.

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