Organometallics 1996, 14, 5475-5477
5475
Synthesis and Solid-state Structure of [Cus(ButCW)2(bpy)41 [CFsS0313*CH~C12: An Unusual Cationic Organocopper(1)Complex Held Together by Two Bridging Alkynyl Ligands Daniel L. Reger," James E. Collins, and Mark F. Huff Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208
Arnold L. Rheingold and Glenn P. A. Yap Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716 Received August 7, 1995@
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Summary: The reaction of Cu(NCMe)4(O&!Fd with LiC=CBut and 2,2'-bipyridine in a n approximate 51214 molar ratio leads to the formation of [Cus(ButC=C)2(bpy)J[CF3SO&. The solid-state structure shows that the cation contains a nearly planar array of five copper atoms held together solely by two bridging alkynyl ligands.
plane and the Cu2 and Cu4 atoms 0.15 on the other side, with Cu5 only 0.010 8, out of the plane. The Cul..*Cu5.--Cu3 angle is 172.4(1)', and the Cu2.mCu5*-*Cu4angle is 173.3'. The Cul-.Cu5 and Cu3*.. Cu5 separations are similar at 2.482(2) and 2.458(2) and shorter than the Cu2...Cu5 and Cu4-.-Cu5 separations of 2.810(2) and 2.707(2) Four of the copper atoms, Cul-4, are bonded to As part of a long-term investigation of transitionbipyridine ligands that are arranged in parallel pairs metal complexes of alkynes,' we have discovered an on each side of the cation. Cul and Cu3 are also weakly unusual class of multimetal, cationic alkynylcopper(1) coordinated to one oxygen atom from the CF3S03 anions. derivatives stabilized by bipyridine (bpy) ligands. ReThe cation is held together by the two bridging ButC=C ported here are the syntheses of compounds containing the unusual cationic organocopper group [Cus(aIkynyl)~- ligands. The terminal carbon atoms of the two alkynyl ligands symmetrically bridge the shorter Cu**.Cudis(bpy)4I3+,which contain a nearly planar Cug central core tances. The Cul-C43 and Cu3-C49 distances of 1.966held together by two bridging alkynyl ligands. The (8) and 1.976(8) compound [ C U ~ ( B U ~ C ~ C ) ~ ( ~ ~ ~ ) ~ ~has [ C F ~ S ~ ~ I ~ ~ C H Zare C ~just Z slightly longer than the Cu5C43 and Cu5-C49 distances of 1.924(9) and 1.942(10) been characterized in the solid state by X-ray crystalA. Cu5 is two-coordinate, bonded only to C43 and C49 lography. A second class of complexes containing a cation with the empirical formula [Cu3(alkynyl)(bpy)3I2+ with a nearly linear C43-Cu5-C49 bond angle of 178.2(4)'. The Cu2 and Cu4 atoms are held in the cation has also been prepared. solely by symmetrical n-bonding interactions to the Treatment of a THF solution of Cu(NCMe)4(03SCF3) carbon-carbon triple bonds, with typical Cu-C diswith LiC=CBut and 2,2'-bipyridine in an approximate tances averaging 2.02 A.4 The c-C alkyne distances 51214 molar ratio leads to the precipitation of [Cup are 1.245(11) and 1.211(12) just slightly longer than ( B U ~ C = C ) ~ ( ~ ~ ~ ) ~ ] [The C F ~solid-state S O ~ I ~ .structure ~ of 1.21 in free alkynes and the normal distances of the CH2Cl2 solvate has been determined crystallotypical of alkynes bonded t o transition metals that do A PLUTO diagram of the cationic part of graphi~ally.~ not strongly back-bond.lb The C43-C44-C45 and the compound, showing the two coordinated CF3S03 C49-C5O-C51 bond angles are 156.4(8)and 159.3(8)', groups, is shown in Figure 1. The five copper(1) atoms of Cu(I)-y2-alkyne structure^.^ The drawagain typical are arranged in a nearly planar array. The Cul and Cu3 atoms are 0.14 A on one side of the least-squares
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(3) A single crystal, grown from CHzClfiexane, of [Cus(bpy),-
(C~CBut)~1[03SCF31~.CH~Clz was mounted, immediately upon removal Abstract published in Advance ACS Abstracts, November 15,1995. (1)(a) Reger, D. L. Acc. Chem. Res. 1988,21,229. (b) Reger, D.L.; Klaeren, S.A,; Lebioda, L. Organometallics 1988, 7, 189. (c) Reger, D. L.; Huff, M. F. Organometallics 1990, 9, 2807. (d) Reger, D. L.; Huff, M. F. Organometallics 1992, 11,69. (2) Cu(NCMe)4(03SCF3)(0.50 g, 1.3 mmol) was dissolved in THF (8 mL). This solution was treated dropwise by cannula transfer with a THF (5 mL) solution of LiC=CBut (0.047 g, 0.53 mmol) and 2,2'bipyridine (0.17 g, 1.1 mmol). A yellow solid precipitated while the mixture was stirred overnight. This solid was collected and washed with hexanes (3 x 5 mL; 0.21 g, 0.14 mmol, 51%). Slow diffusion of hexanes into a saturated CHzClz solution provided crystals which were collected and dried (crystals turn into a powder) to yield [Cu5(bpy),(C~CBut)~1[0~SCF~1~.0.5CH~Cl~ (0.18 g, 0.11 mmol, 43%); mp 158165 "C. Half an equivalent of CHzClz is retained by the compound, as determined by 'H NMR and elemental analysis. 'H NMR (acetone&): d 8.97, 8.51, 8.22, 7.71 (br, d, J = 8.0 Hz, m, m; 8, 8, 8, 8; bpy); 5.63 (s; 1; CHzClZ); 1.56 (s; 18; C(CH3)3). 13C NMR (acetone-&): d 152.3, 150.3, 140.9, 127.4, 122.8 (bpy); 122.3 (9; OsSCF3); 98.6 (C=CBut); 88.8 (br; C=CBut); 32.9 (C(CH&); 32.1 (C(CH3)3). Anal. Calcd for C ~ ~ H ~ & U ~ F ~ N ~ O ~ S ~ *C,O41.81; . ~ C HH,Z 3.22; C ~ ZN, : 7.03. Found: C, 41.15; H, 3.23; N,6.75. @
0276-7333/95/2314-5475$09.00/0
from the mother liquor (crystals degrade rapidly when dry, even under
Nz), with epoxy cement at the end of a glass fiber. All specimens studied diffracted weakly, in keeping with the ionic composition of the compound. Photographic characterization revealed no symmetry greater than triclinic. Data collection was performed a t 298 K on a Siemens P4 diffractometer with Mo K a graphite-monochromated radiation (2. = 0.7107 A). A total of 7430 reflections (4 5 20 5 48") were collected, with 4685 being observed having I > 40. Corrections for absorption were applied using a semiempirical procedure (transmission ratio 1.24). Direct methods were used to locate the metal atoms. Due to the large number of parameters refined (5491, blocked methods were used. Only atoms with atomic numbers of 7 or greater were refined with anisotropic thermal parameters, and hydrogen atoms were idealized (R(F)= 5.14; R,(F) = 6.23). All computations used the SHELXTL 4.2 library of programs (G. Sheldrick, Siemens XRD, Madison, WI). Crystal-data for C ~ ~ H ~ Z C ~ Z C U ~ Ffw~ = N 1648.0, EO~S~: triclinic, space group P1,a = 11.570(3) A, b = 15.650(4)A, c = 19.072(6) A, a = 86.76(2)", /3 = 73.42(2)", y = 79.18(2)", V = 3250(1) A3, 2 = 2, De,), = 1.672 g ~ m - p~ =, 18.7 cm-l. (4) (a) Reger, D. L.; Huff, M. F.; Wolfe, T. A,; Adams, R. D. Organometallics 1989, 8, 848. (b) Pasquali, M.; Leoni, P.; Floriani, C.; Gaetani-Manfredotti, A. Inorg. Chem. 1982,21, 4324.
0 1995 American Chemical Society
5476 Organometallics, Vol. 14, No. 12, 1995
Communications
In the cation [CwPh2(PMDTA)#, the Cu--Cu distances are 2.444 A,less than 0.03 A shorter than the average of the Cul***Cu5 and Cu3-Cu5 separations. The Cu-C distances of 2.006(7), 1.989(5), 1.980(7), and 2.064(5) A are slightly longer, with the shorter distances to the central copper atom as observed in the Cu5 cation. C These slightly longer Cu-C bonds are explained by the fact that the bridging carbon atoms in this structure are sp2-hybridized, whereas in the structure of [Cug(ButC=C)2(bpy)4I3+the bridging carbon atoms are sphybridized. The main difference in the two structures is that the presence of the two C-C triple bonds in [Cugc19 (ButC=C)2(bpy)4I3+allows the coordination of two additional (bipyridine)copper(I)groups. Two other compounds containing the [CU~(RC=C)~(bpy)4J3+cation have been prepared.6 A reaction similar to that described above using Cu(NCMe)4(PF6)with LiC=CBut and 4,4'-dimethylbipyridine yields, after crystallization from CH&l&exane, [Cus(Mesbpy)4b F6 (C~CBut)2][PF6]3.0.5CH2C12. Reaction of Cu(NCMe)4Figure 1. Pluto drawing of [Cu5(bpy)4(C~CBut)2(03- (SbF6)with L i C e P h and 4,4'-dimethylbipyridine yields [Cus(Me2bpy)4(C=CPh)2][SbF613. Both of these comSCF3)21+ showing the atomic labeling scheme. Selected distances (A): Cul-Cu5 = 2.482(2),Cu2-Cu5 = 2.810pounds have been characterized in the solid state by (21, Cu3***Cu5 = 2.458(2),Cu4***Cu5 = 2.707(2),Cul***C43 X-ray crystallography, but the structures suffered dis= 1.966(8), Cu2-C43 = 2.018(8), Cu2-C44 = 2.010(8), order problems. In both cases the structures of the Cu3-C49 = 1.976(8), Cu4-C49 = 2.038(8), Cu4-C50 = cations were clearly identified and are essentially the 2.016(8), C~5-C43 = 1.924(9), Cu5-C49 = 1.942(10), same as that observed for [Cug(ButC~C)2(bpy)41[CF3C43-C44 = 1.245(11),C49-C50 = 1.211(12),Cul-01 = SO3]3*CH2C12. 2.327(8), Cu3-04 = 2.267(11). Seleded angles (deg): cul***Cu5***Cu2 = 85.6(1), Cul***Cu5***Cu3 = 172.4(4), Surprisingly, a similar reaction using Cu(NCMe)4Cul***Cu5***Cu4 = 94.4(1), Cu2***Cu5***Cu3 = 90.3( l), (PF6)with LiC=CBut and 2,Z-bipyridine yields a comC U ~ * * * C U ~ *=* *173.3( C U ~l), Cu3***Cu5***Cu4 = 90.q l), pound with an entirely different empirical formula, c43-Cu5-C49 = 178.2(4), C43-C44-C45 = 156.4(8), [CU~(~~~)~(C=CBU~)][PF~]~*O.~CH~C~~.~ Repeated atC49-C5O-C51 = 159.3(8). tempts to grow single crystals of this compound that are suitable for a crystallographic study have not proven Chart 1 successful. A reasonable structure would have the three 0 -1 copper atoms, two bpy ligands, and the bridging alkynyl ligands arranged as in the top of Chart 1. The Cup (alkynyl)(bpy):!group would be removed fiom the bottom of the drawing and replaced with a bpy ligand bonded to the central copper atom. This synthesis indicates that additional cationic alkynylcopper(1) compounds stabilized by chelating nitrogen donor ligands are possible. Chart 2
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ing in Chart 1 depicts the bonding of the central Cu5 core and the donor atoms bonded to it. This structure represents the second example of a cationic organocopper(1)complex. The first is the trimetallic cation [Cu3Ph2(PMDTA)2]+(PMDTA = NJV,N',N,N"-pentamethyldiethylenetriamine).5 A drawing of the CU&~N~core of this cation is shown in Chart 2. The structure is remarkably similar to the linear Cu3@-C)2part of the Cu5 cation that runs from the top left to the bottom right of Chart 1. Even the terminal copper atoms are bonded to three other donor atoms. W H e , X.; Ruhlandt-Senge, IC; Power, P. P.; Bertz, S. H. J. Am. Chem. Soc. 1994,116,6963.
(6)[Cus(Me2bpy)4(C~CBurkl[PFsls was prepared as described in ref 2 (0.34 g, 0.21 mmol; 77%) using Cu(NCMe14PF6 (0.50 g, 1.3 mmol), LiCSCBu' (0.047 g, 0.53 mmol), and 4,4'-Me2bpy (0.20 g, 1.1 mmol). Crystallization from CHzClhexanes provided analytically pure ICu5(Me2bpy)4(C~CBu'kllPF613.0.5CH2Ci2. H NMR (acetoneds): 8.77, 8.35, 7.54 (s,S, S; 8, 8, 8; bpy); 5.63 (s;1; CH2C12); 2.52 (s; 24; (H3c)2' bpy); 1.57 (s; 18;C(CH313). Anal. Calcd for C ~ H M C U ~ F ~ & P ~ * O . ~ C H ~ C12: C, 42.89; H, 3.99; N, 6.61. Found: C, 42.88; H, 4.03; N, 6.69. [Cus(Mesbpy)4(CICPh)zl[SbFsls was prepared as described in ref 2 from Cu(NCMe)4SbF6(0.500g, 1.08 mmol), 4,4'-M~bpy(0.16 g, 0.86 mmol), and LiCECPh (0.047 g, 0.43 mmol) in THF (30 mL). The yellow powder that formed over ca. 2.5 h was filtered and dried overnight in vacuo (0.221 g, 0.113 mmol, 52%). lH NMR (acetone-&): d 8.59,8.31, 7.43 (s, s, s; 8, 8, 8; bpy); 7.90, 7.58 (d; m; J = 8 Hz; 4, 6; C a s ) ; 2.49 (s; 24; (H3Chbpy). (7) [Cu3(bpy)3(CI=CBut)~rPF612 (0.37 g, 0.36 mmol, 80%) was prepared by treating a THF (10 mL) solution of Cu(NCMe)dPFe (0.50 g, 1.3 mmol) and 2,2'-bipyridine (0.21 g, 1.3 mmol) with a THF (5 mL) solution of LiCsCBu' (0.039 g, 0.45 mmol) by slow cannula transfer. After the mixture was stirred overnight, the product was isolated as described above for [Cu~(bpyk(C~CBut)2l[0sSCFs13; mp 210-215 "C. Crystallization from CHnClhexanes provided analytically pure ICu3(bpy)3(C1CBuL)l[PF612.0.5CH2C12. lH NMR (acetone&): b 8.98, 8.59,8.27,7.73 (br d, J = 7.1, m, m; 6,6,6,6; bpy); 5.63 (5; 1; CH2C12); 1.66 (s; 9;C(CH313). 13C" M R (acetoneds): d 152.5,150.3,140.8,127.5, 122.9 (bpy); 88.7 (CsCBuL);34.2 (C(CH313);32.9 (C(CH3)3). Anal. Calcd C, 40.87; H, 3.19; N, 7.83. Found: for C36H33C~nF~2N6P2~O.5cH2cl2: C, 40.45; H, 3.21; N, 7.46.
Communications
Acknowledgment is made to Professor Lucas Lebioda for solving the crystal structure of [Cus(Mezbpy)c( C ~ C p h ) ~ l [ S b FThe ~ l ~NSF . (Grants CHE&11172 and CHE-8904942) and NIH (Grant RR-02425) have supplied funds to support NMR equipment a t the University of South Carolina.
Organometallics, Vol. 14, No. 12, 1995 5477 Supporting Information Available: Tables of complete data collection information, bond distances, angles, anisotropic thermal parameters, and positional parameters and a stereoview of the unit cell (13pages). Ordering information is given On any current masthead page.
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