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Do Aurophilic Interactions Compete Against Hydrogen Bonds? Experimental Evidence and Rationalization Based on Ab Initio Calculations Antonio Codina, Eduardo J

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Do Aurophilic Interactions Compete Against Hydrogen Bonds? Experimental Evidence and Rationalization Based on Ab Initio Calculations Antonio Codina, Eduardo J Published on Web 05/18/2002 Do Aurophilic Interactions Compete against Hydrogen Bonds? Experimental Evidence and Rationalization Based on ab Initio Calculations Antonio Codina, Eduardo J. Ferna´ndez, Peter G. Jones, Antonio Laguna,* Jose´ M. Lo´pez-de-Luzuriaga, Miguel Monge, M. Elena Olmos, Javier Pe´rez, and Miguel A. RodriÄguez Contribution from the Departamento de Quı´mica, UniVersidad de La Rioja Grupo de Sı´ntesis Quı´mica de La Rioja, UA-CSIC, Madre de Dios 51, E-26004 Logron˜o, Spain, Institut fu¨r Anorganische und Analytische Chemie der Technischen UniVersita¨t, Hagenring 30, D-38106 Braunschweig, Germany, and Departamento de Quı´mica Inorga´nica-ICMA, UniVersidad de Zaragoza-CSIC, E-50009 Zaragoza, Spain Received January 31, 2002 Abstract: [M(C6F5){N(H)dCPh2}](M) Ag (1) and Au (2)) complexes have been synthesized and characterized by X-ray diffraction analysis. Complex 1 shows a ladder-type structure in which two [Ag- (C6F5){N(H)dCPh2}] units are linked by a Ag(I)-Ag(I) interaction in an antiparallel disposition. The dimeric units are associated through hydrogen bonds of the type N-H‚‚‚Fortho. On the other hand, gold(I) complex 2 displays discrete dimers also in an antiparallel conformation in which both Au(I)-Au(I) interactions and N-H‚‚‚Fortho hydrogen bonds appear within the dimeric units. The features of these coexisting interactions have been theoretically studied by ab initio calculations based on four different model systems in order to analyze them separately. The interactions have been analyzed at HF and MP2 levels of theory showing that, in this case, even at larger distances. The Au(I)-Au(I) interaction is stronger than Ag(I)-Ag(I) and that N-H‚‚‚F hydrogen bonding and Au(I)-Au(I) contacts have a similar strength in the same molecule, which permits a competition between these two structural motifs giving rise to different structural arrangements. Introduction some physical properties.5 Nevertheless, in most cases the formation of polymeric structures6 or the ligand architecture Aurophilicity is the tendency of closed-shell gold(I) atoms plays a significant role in the aggregation of the metal centers to aggregate at distances shorter than the sum of the van der and there are few examples of unsupported Ag(I)-Ag(I) or Waals radii with an interaction energy that is comparable in Cu(I)-Cu(I) interactions;7 this may indicate that these are strength to hydrogen bonds.1 It is important to note that this weaker than those of Au(I)-Au(I), leaving the metallophilicity aggregation is an intrinsic effect of the metal centers and is not concept as a matter for discussion. imposed by the ligand architecture; this has been demonstrated In contrast, hydrogen bonds are well established as structural in a large number of experimental and theoretical reported exam- motifs for the construction of molecular networks. These interac- ples2 and, in principle, gold-gold interactions could be used to tions have been widely reviewed by Desiraju showing that control supramolecular structures and their dimensionality.3 several organometallic molecules bind into crystal architectures This effect has prompted a number of research groups to seek through intermolecular hydrogen bonds.8 Indeed, hydrogen similar situations in other closed-shell metal atoms of the same bonding is known as the master-key interaction in crystal engi- period or even the same group. Thus, argentophilicity or even neering because it combines directionality with strength. On cuprophilicity are terms coined to describe the analogous the other hand, hydrogen bonding has been extensively studied phenomena and have also been theoretically analyzed.4 These metallophilic interactions are considered to be responsible for (4) (a) Pyykko¨, P.; Runeberg, N.; Mendizabal, F. Chem. Eur. J. 1997, 3, 1451. (b) Pyykko¨, P.; Mendizabal, F. Inorg. Chem. 1998, 37, 3018. (c) Ferna´ndez, E. J.; Lo´pez-de-Luzuriaga, J. M.; Monge, M.; Rodrı´guez, M. A.; Crespo, * Corresponding author. E-mail: [email protected]. O.; Gimeno, M. C.; Laguna, A.; Jones, P. G. Inorg. Chem. 1998, 37, 6002. (1) (a) Schmidbaur, H.; Graf, W.; Mu¨ller, G. Angew. Chem., Int. Ed. Engl. (5) (a) Che, C. M.; Tse, M. C.; Chan, M. C. W.; Cheung, K. K.; Phillips, D. 1988, 27, 417. (b) Harwell, D. E.; Mortimer, M. D.; Knobler, C. B.; Anet, L.; Leung, K. H. J. Am. Chem. Soc. 2000, 122, 2464. (b) Che, C. M.; F. A. L.; Hawthorne, M. F. J. Am. Chem. Soc. 1996, 118, 2679. (c) Pyykko¨, Mao, Z.; Miskowski, V. M.; Tse, M. C.; Chan, C. K.; Cheung, K. K.; P.; Zhao, Y. F. Angew. Chem., Int. Ed. Engl. 1991, 30, 604. (d) Pyykko¨, Phillips, D. L.; Leung, K. H. Angew. Chem., Int. Ed. 2000, 39, 4084. P.; Li, J.; Runeberg, N. Chem. Phys. Lett. 1994, 218, 133. (e) Bachman, (6) Tong, M. L.; Chen, X. M.; Ye, B. H.; Ji, L. N. Angew. Chem., Int. Ed. R. E.; Fioritto, M. S.; Fetics, S. K.; Cocker, T. M. J. Am. Chem. Soc. 2001, 1999, 38, 2237. 123, 5376. (7) (a) Eastland, G. W.; Mazid, M. A.; Russell, D. R.; Symons, M. C. R. J. (2) Pyykko¨, P. Chem. ReV. 1997, 97, 597. Chem. Soc., Dalton Trans. 1980, 1682. (b) Boche, G.; Basold, F.; Marsch, (3) Leznoff, D. B.; Xue, B. Y.; Batchelor, R. J.; Einstein, F. W. B.; Patrick, M.; Harms, K. Angew. Chem., Int. Ed. Engl. 1998, 37, 1684. B. O. Inorg. Chem. 2001, 40, 6026. (8) Desiraju, G. R. J. Chem. Soc., Dalton Trans. 2000, 3745. 10.1021/ja025765g CCC: $22.00 © 2002 American Chemical Society J. AM. CHEM. SOC. 2002, 124, 6781-6786 9 6781 ARTICLES Codina et al. from a theoretical point of view giving a rich source of Table 1. Details of Data Collection and Structure Refinement for supplementary information concerning this phenomenon.9 Complexes 1 and 2 Going further, self-assembled supramolecular architectures compd. 12 formula C19H11AgF5NC19H11AuF5N are currently of great interest. In this context, a number of gold- formula weight 456.16 545.25 10 11 (I) and silver(I) structures in which Au(I)-Au(I) or Ag(I)- T (K) 173(2) 293(2) Ag(I) interactions coexist with hydrogen bonds have been wavelength (Å) 0.71073 0.71073 reported. Thus, the competition between hydrogen bonding and crystal size (mm) 0.7 × 0.4 × 0.1 0.25 × 0.23 × 0.20 crystal system monoclinic monoclinic metallophilic interactions in the same crystal structure would space group P21/cP21/c lead to a delicate balance between both structural motifs. a (Å) 13.5320(16) 13.6780(4) Most of the literature regarding metallophilicity and hydrogen b (Å) 5.6217(8) 7.6814(3) c (Å) 21.626(3) 17.4676(5) bonding has taken the crystallographic or spectroscopic point â (deg) 95.168(9) 109.807(2) of view. Although metal-metal interactions and H-bonds have V (Å3) 1638.5(4) 1726.68(10) been separately studied by theoretical calculations, as far as we Z 44 3 know, there is no report that emphasizes the theoretical Dcalc (mg/m ) 1.849 2.097 R -1 - µ(Mo K ) (mm ) 1.285 8.752 comparison between gold gold interactions and hydrogen bonds θ range for data collect. (deg) 3.02 to 25.00 2.93 to 20.81 coexisting in the same molecule. no. of reflcns. collected 4295 4186 In this context, we now report the synthesis and structural R(int) 0.0172 0.0599 no. of independent reflcns 2884 1806 characterization of the organometallic compounds [M(C6F5)- absorption correction Ψ-scans multiscan {N(H)dCPh2}](M) Ag (1), Au (2)) in which Ag(I)-Ag(I) data/restraints/parameters 2884/0/239 1806/97/235 or Au(I)-Au(I) intermetallic interactions coexist with hydrogen goodness-of-fit on F2 1.032 1.084 bonds. Ab initio calculations have been carried out in order to final R indices [I > 2σ(I)] 0.0187, 0.0464 0.0339, 0.08 (R1, wR2) explain the role of these structural motifs in the formation of R indices (all data) (R1, wR2) 0.0233, 0.0476 0.0487, 0.0865 the crystal structures in the solid state. largest diff. peak and 0.300 and -0.330 0.964 and -1.854 hole (e‚Å-3) Experimental Section General. The reactions were carried out under an argon atmosphere -1 19 - and the solvents were dried by standard methods prior to use. 3308 cm . F NMR((CD3)2CO, room temperature, ppm): δ 106.40 (m, 2F, F ); δ -160.71 (t, 1F, F , 3J(F -F ) ) 19.5 Hz); δ -162.68 Benzophenoneimine ligand and AgClO4 are commercially available and o p p m (m, 2F, F ). 1H NMR((CD ) CO, room temperature, ppm): δ 10.48 were purchased from Aldrich. The rest of the starting materials, NBu4- m 3 2 12 12 13 (s, 1H; N-H); δ 7.58-7.92 (m, 10H; Ph). ES(+) m/z (%): 288 (5) [Ag(C6F5)2], [Ag(C6F5)], and [Au(C6F5)(tht)], were prepared ac- d + d + - cording to the literature. [Ag(N(H) CPh2)] , 441 (100) [Ag(N(H) CPh2)2] . ES( ) m/z (%): - Infrared spectra were recorded in the range of 4000-200 cm-1 on 441 (100) [Ag(C6F5)2] . { d } a Perkin-Elmer FT-IR Spectrum 1000 spectrophotometer with Nujol [Au(C6F5) N(H) CPh2 ] (2): To a dichloromethane solution of d mulls between polyethylene sheets. C, H, N analysis was carried out [Au(C6F5)(tht)] (0.181 g, 0.4 mmol) was added N(H) CPh2 (0.066 mL, on a EA 1110 CHNS-O microanalyzer.
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