Solid-State Packing of the Square-Planar - American Chemical Society

Nov 20, 2007 - One specific feature of the structure of compounds 3 and 4 is that the Rh–bim monomers form planes that are nearly parallel with the ...
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Solid-State Packing of the Square-Planar [RhI(H2bim)(CO)2]2[A] Complexes (H2bim ) 2,2-biimidazole; [A] ) 2[Cl], 2[RhICl2(CO)2], [FeIICl4], [CoIICl4]) Minna Jakonen, Larisa Oresmaa, and Matti Haukka*

CRYSTAL GROWTH & DESIGN 2007 VOL. 7, NO. 12 2620–2626

UniVersity of Joensuu, Department of Chemistry, P.O. Box 111, FI-80101 Joensuu, Finland ReceiVed June 25, 2007; Accepted August 22, 2007

ABSTRACT: A series of ionic rhodium(I) complexes with the 2,2-biimidazole (H2bim) ligand were synthesized and characterized. The square-planar Rh(I) complexes were synthesized by reductive carbonylation of the RhCl3 in the presence of H2bim and a sacrificial metal surface (Fe or Co) in an autoclave (50 bar, 125 °C, 3–30 h). The solid-state structures of the complexes were determined by single-crystal X-ray diffraction. The basic backbone of all of the complexes was a 16-electron [RhI(H2bim)(CO)2]+ cation. The reaction conditions (reaction time, sacrificial metal surface) determined the counteranion. The cationic [RhI(H2bim)(CO)2]+ was obtained in crystalline form with four different anions: [Cl]-, [RhICl2(CO)2]-, [FeIICl4]2-, and [CoIICl4]2-. All of the complexes were crystallized as dinuclear [RhI(H2bim)(CO)2]22+ moieties in which the distances between the RhI centers were in the range of 3.28–3.38 Å. These dinuclear systems, held together by weak metal–metal interactions between two [RhI(H2bim)(CO)2]+ units, were connected to each other via weak interactions between the metal and the π system of the H2bim ligand of the neighboring molecule, or via the π interactions between aromatic ligands. The anion was found to have an essential impact on the crystal packing and separation of the metal centers in the complexes. The interactions between the nearest H2bim ligands in the crystal structure were also dependent on the nature and size of the counteranion and also on the interactions between the cation and the anion. Introduction Square-planar geometry in metal complexes allows stacking in the solid state and allows the compound to interact with another unit; as a consequence, the formation of a metal chain is also possible.1 d8 metal chains of this type, consisting of square-planar units, have a variety of properties, such as magnetic,2 spectroscopic, and luminescent properties.3 There are also examples of metal chains with strong metal–metal bonds that are catalytically active in processes such as the water gas shift reaction and CO2 reduction.4,5 Among the organometallic compounds, rhodium can appear as a 16-electron compound. In these cases, rhodium is electron deficient and coordinatively unsaturated. Such features make these systems prone to stacking and allow the formation of oligomers,6 polymers with metal–metal bonds,7 and chains with weak metal–metal interactions between the rhodium atoms.8 The square-planar geometry is normal in the complexes of RhI, and therefore, most of the rhodium chains are also made up of d8 Rh units.9 These d8 chains can be formed via weak metal interactions. The typical distance between two RhI’s in extended metal chains is in the range of 3.25–3.68 Å.8 In addition, rhodium square-planars can form a dinuclear unit, which interacts with another similar unit via weak metal–metal interactions,8,10 metal and ligand,11,12 and, most frequently, the aromatic system.12 In these cases, the distance between the metals in the dinuclear unit varies from 3.23 to almost 4 Å.12,13 The aromatic heterocyclic 2,2′-biimidazole ligand forms complexes with a number of transition metals. There are many examples of mono-,14 bis-,15 and also tris-biimidazole compounds.16 The compounds of copper,16 and palladium,14e can appear in square-planar coordination. In addition, biimidazole complexes of rhodium are also known in which the oxidation state of rhodium is commonly one or three and the coordination * Corresponding author. Fax: +358-13-251 3390. E-mail: matti.haukka@ joensuu.fi.

Figure 1. Synthesized complexes 1–4.

number is four or six.18,19 Typically, biimidazole is a chelating ligand, but it can also serve as a bridge between two Rh centers.18c In the present study, a surface-assisted synthesis was applied in the preparation of monometallic and mixed-metal rhodium complexes. Four ionic 16-electron RhI square-planar complexes, presented in Figure 1, were synthesized and characterized. Single-crystal X-ray diffraction and attenuated total reflection– infrared spectroscopy (ATR-IR) were used for the solid-state characterization of the complexes. The solid-state packing of complexes 1–4 is discussed in terms of the role of the anion. Experimental Section Materials. The RhCl3 (Rh 38.5–45.5%) was produced by Alfa Aesar. The Co (99.9%, CO000279/3) and Fe (99.5%, FE000400/11) were manufactured by Good Fellow Co. The MeOH and CH2Cl2 (99.9%) was purchased from Fluka. The carbon monoxide (98%) used in the reactions was produced by AGA, and the EtOH (99.5%) by Primalco. Measurement Techniques. The FTIR spectra were recorded using a Nicolet Magna IR Spectrometer750 (measurements in CH2Cl2), and the 1H NMR and 13C NMR spectra were recorded on Bruker Avance 400 MHz and Avance 250 MHz machine, respectively. ATR-IR measurements were performed using an FTS 7000 Series DIGILAB FTIR spectrometer equipped with a UMA 600 DIGILAB microscope. A CE Instruments EA 110 CHNS-O machine was used in the C, N, and H analysis of the products. Qualitative analyses of C, N, O, Cl, Fe, Co, and Rh were conducted using an FE-SEM Hitachi S-4800 Scanning Electron Microscope equipped with a Norman System Six energy dispersive spectrometer (EDS).

10.1021/cg070577t CCC: $37.00  2007 American Chemical Society Published on Web 11/20/2007

Square-Planar [RhI(H2bim)(CO)2]2[A] Complexes

Crystal Growth & Design, Vol. 7, No. 12, 2007 2621 Table 1. Crystal Data

empirical formula fw temp (K) λ(Å) cryst syst space group a (Å) b (Å) c (Å) β (deg) V (Å3) Z Fcalc (mg/m3) µ(Mo KR) (mm-1) no. reflns. unique reflns. R1a (I g 2σ) wR2b (I g 2σ) a

1

2

3

4

C8H6ClN4O2Rh 328.53 120(2) 0.71073 monoclinic P21/c 13.8955(14) 9.4945(10) 16.461(2) 92.421(9)° 2169.8(4) 8 2.011 1.809 34545 5498 0.0246 0.0449

C10H6Cl2N4O4Rh2 522.91 120(2) 0.71073 monoclinic P21/c 10.5835(15) 42.639(5) 7.0497(7) 107.101(10) 3040.6(7) 8 2.285 2.542 23990 6616 0.0370 0.0577

C16H12Cl4FeN8O4Rh2 783.81 120(2) 0.71073 monoclinic P21/n 13.6176(9) 10.8665(3) 17.6520(9) 108.360(2) 2479.1(2) 4 2.100 2.365 18412 5662 0.0413 0.0814

C16H12Cl4CoN8O4Rh2 786.89 120(2) 0.71073 monoclinic P21/n 13.5720(4) 10.8474(4) 17.6778(4) 108.279(2) 2471.22(13) 4 2.115 2.457 33608 5632 0.0410 0.0943

R1 ) ∑|Fo – Fc|/∑Fo. b wR2 ) [∑[w(Fo2 – Fc2)2]/∑[w(Fo2)2]]1/2. Table 2. Selected Bond Lengths (Å) and Angles (deg) anions 2[RhICl2(CO)2]- in compound

I

cation [Rh (H2bim)(CO)2]22+ in compounds Rh1–N1 Rh1–N2 Rh1–C1 Rh1–C2 Rh1–Rh1B Rh1–Rh1B (a) Rh1B–N1B Rh1B–N2B Rh1B–C1B Rh1B–C2B N1–Rh1–N2 C1–Rh1–C2 N1B–Rh1B–N2B C1B–Rh1B–C2B a

1

2

3

4

2.089(2) 2.078(2) 1.855(3) 1.865(2) 3.2986(4)

2.070(3) 2.077(4) 1.858(5) 1.873(5) 3.2795(5) 4.0449(6) 2.082(4) 2.084(3) 1.870(5) 1.863(5)

2.071(4) 2.081(4) 1.860(5) 1.855(5) 3.3770(6)

2.068(4) 2.080(4) 1.855(5) 1.862(6) 3.3656(5)

2.068(4) 2.084(4) 1.863(5) 1.864(5)

2.068(4) 2.084(4) 1.869(5) 1.870(5)

78.86(14) 90.0(2) 78.78(14) 88.1(2)

78.67(16) 90.3(2) 79.22(14) 88.7(2)

2.079(2) 2.071(2) 1.859(2) 1.855(3) 79.21(7) 89.30(10) 79.16(7) 89.74(10)

79.13(13) 89.99(19) 78.83(13) 89.9(2)

2 Rh2–Cl1 Rh2–Cl2 Rh2–C9 Rh2–C10 Rh2B–Cl1B Rh2B–Cl2B Rh2B–C9B Rh2B–C10B Rh2–Rh2B (b) Rh2–Rh2B (c) Rh2B–Rh2B (d) Cl1–Rh2–Cl2 C9–Rh2–C10 Cl1B–Rh2B–Cl2B C9B–Rh2B–C10B

2.3655(12) 2.3897(13) 1.843(5) 1.832(5) 2.3683(12) 2.3757(13) 1.835(5) 1.842(5) 3.4623(7) 3.8152(7) 3.6156(4) 89.45(4) 89.1(2) 91.16(4) 91.4(2)

Symmetry transformations used to generate equivalent atoms: (a) x, y, z - 1; (b) –x + 2, –y, –z + 2; (c) –x + 2, –y, –z + 1; (d) x, –y + 1/2, z -

1/2.

X-Ray Crystal Structure Determinations. The crystals were immersed in cryo-oil, mounted in a nylon loop, and measured at a temperature of 120 K. The X-ray diffraction data were collected by means of a Nonius KappaCCD diffractometer using Mo KR radiation (λ ) 0.71073 Å). The Denzo-Scalepack20 or EvalCCD21 program packages were used for cell refinements and data reductions. All of the structures were solved by direct methods using SHELXS-9722 or SIR20023 with the WinGX24 graphical user interface. An empirical absorption correction was applied to all of the data (SADABS25 or XPREP in SHELXTL26). Structural refinements were carried out using SHELXL-97.27 All of the hydrogen atoms were positioned geometrically and constrained to ride on their parent atoms, with C–H ) 0.95 Å, N–H ) 0.88 Å, and Uiso ) 1.2 × Ueq (parent atom). The crystallographic details are summarized in Table 1, and selected bond lengths and angles are given in Table 2. Synthesis and Analysis of the Products. High-Pressure Synthesis of Complexes 1–4. Rhodium trichloride reduction reactions were carried out in a Berghof autoclave equipped with a PTF liner. The solid metals (Fe or Co, 49 mm2, d 0.2–0.3 mm) and 100 mg of RhCl3 and 64 mg of 2,2′-biimidazole were placed in the liner together with 4 mL of ethanol. Some of the reactions were carried out without the additional sacrificial metal surface. The 2,2′-biimidazole ligand was synthesized according to the description presented in the literature.28 An autoclave was pressurized with 50 bar of carbon monoxide, quickly heated to 125 °C, and maintained at that temperature for 3–30 h. After the reaction, the autoclave was cooled to room temperature. The solid products were separated and analyzed. Analysis of Complexes 1–4. [Rh(H2bim)(CO)2][Cl] (1). Reddishorange, needlelike crystals. Anal. calcd for C8H6N4O2ClRh (mol wt,

328.52): C, 29.25; H, 1.84; N, 17.05. Found: C, 29.37; H, 1.93; N, 16.85. IR (in CH2Cl2): ν(CO) 2096, 2032 cm-1. ATR-IR (solid sample): ν(CO) 2096, 2085, 2020 cm-1. 1H NMR for H2bim: δ 7.319 (br) ppm. Yield: 17% (reactions with Fe surface). [Rh(H2bim)(CO)2][RhCl2(CO)2] (2). Orange crystals. Anal. calcd for C8H6N4O2ClRh (mol wt, 522.90): C, 22.97; H, 1.16; N, 10.71. Found: C, 23.03; H, 1.27; N, 10.58. EDS: Found C, N, O, Cl, and Rh. IR (in CH2Cl2): ν(CO) 2097, 2083, 2034, 2008 cm-1. ATR-IR (solid sample): 2099, 2082, 2069, 2039, 2026, 2000, 1987 cm-1. Yield: 10%. [Rh(H2bim)(CO)2]2[FeCl4] (3). Red crystals. Anal. calcd for C16H12N8O4Rh2Cl4Fe (mol wt, 783.79): C, 24.52; H, 1.54; N, 14.30. Found: C, 24.51; H, 1.58; N, 14.20. EDS: Found C, N, O, Fe, Cl, and Rh. IR (in CH2Cl2): ν(CO) 2097, 2032 cm-1. ATR-IR (solid sample): 2100, 2093, 2083, 2039, 2027, 2020, 2014 cm-1. 1H NMR for H2bim: δ 7.346 (br) ppm. Yield: 15%. [Rh(H2bim)(CO)2]2[CoCl4] (4). Green crystals. Anal. calcd for C16H12N8O4Rh2Cl4Co (mol wt, 786.88): C, 24.42; H, 1.54; N, 14.24. Found: C, 24.63; H, 1.60; N, 14.28. EDS: Found C, N, O, Co, Cl, and Rh. IR (in CH2Cl2): ν(CO) 2096, 2033 cm-1. ATR-IR (solid sample): 2093, 2079, 2039, 2027, 2013 cm-1. {1H}-13C NMR for H2bim (in DMSO): δ 182.154 and 181. 443 for (CO); 134.082 and 122.909 for (H2bim) ppm. 1H NMR for H2bim: δ 7.607 (br) ppm. Yield: 10%.

Results and Discussion Synthesis and Characterization of Complexes 1–4. In our previous studies, surface-assisted reactions were applied in the synthesis of mixed-metal complexes of ruthenium and osmium.

2622 Crystal Growth & Design, Vol. 7, No. 12, 2007

In this method, the reductive carbonylation of RuCl3 and OsCl3 was carried out in the presence of a solid metal surface (stainless steel, Fe, or Co) in alcohol solutions. At the same time that the MCl3 (M ) Ru/Os) was reduced, the metal cations (Fe or Co) were released from the sacrificial metal surface, and a variety of ionic and neutral mixed-metal systems, such as chloridebridged [M2Cl2(µ-Cl)4(CO)6M′(L)2] and ionic [M′(H2O)6] [MCl3(CO)3]2 (M ) Ru, Os; M′ ) Fe, Co; L ) H2O, CH3CH2OH) were formed.29 The same reaction setup (20 bar CO, 125 °C, 3 h) was also applied in the reduction of RhCl3 in the presence of a sacrificial metal surface. The major products in these reactions were rather unstable carbonyl-containing rhodium– carbonyl products. Mixed-metal complexes could not be isolated and identified from these reactions even though the corrosion of the metal surface was clearly visible. We found that the addition of 2,2′-biimdazole (H2bim) stabilizes rhodium at the oxidation state of +1 in the complexes that were formed during the reaction in an autoclave (50 bar CO, 125 °C, 3–30 h). All of the complexes isolated from the reactions had the same basic cationic unit [RhI(H2bim)(CO)2]+. The reactions were repeated both with and without the presence of a solid metal surface and with different reaction times (3–30 h) in order to determine the effect of the reaction conditions. Complex 1 [RhI(H2bim)(CO)2][Cl] was found in all of the reactions, but as expected, it was the dominant product in the reactions carried out with no sacrificial metal surface. The crystalline, reddish-orange lustrous needles of complex 1 could be separated rather easily from the reaction solution simply by filtration. When a metal plate was added to the reaction, the mixed-metal complexes 3 and 4 [RhI(H2bim)(CO)2]2[MIICl4] (M ) Fe, Co) were obtained after reactions of only 3 h. Furthermore, when the reaction time was increased from 3 h to 20–30 h, the yields from the mixed metal complexes also increased. The highest yield of the iron-containing red crystals of complex 3 was around 15%. The reaction carried out with cobalt produced green crystals of complex 4 with a total yield of 10%. Complex 2 [RhI(H2bim)(CO)2][RhICl2(CO)2] was also observed in the reactions involving metal plates, especially in the context of shorter reaction times. The total amount of orange crystals separated in complex 2 was ca. 10%. The elemental composition of complexes 2–4 was verified by means of EDS measurements of the isolated crystals. The measurement confirmed the element content of the complexes and the presence of mixed-metal complexes. The FTIR spectra of complexes 1–4 were measured in CH2Cl2. The characteristic pattern of two ν(CO) signals was found in the IR spectra of complexes 1–4 at around 2096 and 2032 cm-1. These bands originated from the cationic unit [RhI(H2bim)(CO)2]+. In complex 2, two additional signals with wave numbers of 2083 and 2008 cm-1 emerged as a result of the counteranion [RhCl2(CO)2]-. In the solution, the similarities between the ν(CO) signals of the cation are due to the fact that the there were no significant interactions between the [RhI(H2bim)(CO)2]+ units. In each case, they were isolated by the solvent in more or less the same way. In the solid state, differences based on different packing emerged. The IR spectra of the crystalline complexes were analyzed in the solid state using the ATR-IR technique. The differences in the metal–metal interactions in complexes 1–4 were clearly reflected in the solid-state IR. In each case, the spectra were more complicated by multiple signals. As a general feature, all of the spectra contained two broad, dominant signals within the same wave number range of 2100–2070 cm-1 and 2040–2015 cm-1. In addition, in the spectra of compound 2,

Jakonen et al.

Figure 2. The thermal ellipsoid plot (50% probability level) of [RhI(H2bim)(CO)2]2[Cl]2 (1).

there was also an additional broad signal at around 2000 cm-1. However, because of the varying anion, the shapes and detailed positions of the bands were unique for each complex, 1–4. In compounds 1, 3, and 4, in which there were no carbonyls in the anion, two principal peaks were observed, whereas in the spectra of compound 2, in which the rhodium anion contained carbonyls, there were three major peaks to be seen. However, each complex displayed distinct IR patterns, and even structurally very similar compounds 3 and 4 could be identified by solidstate IR.30 The IR study refers that, in the solvent, compounds 1–4 are mononuclear, while in the solid state, there are some additional interactions between monomers. Similarly behaving rhodium carbonyl complexes have previously been introduced by Usón et al.31 Solid-State Structure of Complexes 1–4. In complexes 1–4, the asymmetric unit in the crystal structure consists of a dinuclear backbone formed by two [RhI(H2bim)(CO)2]+ units, held together by weak metal–metal interactions. The counteranion (Cl-, [RhICl2(CO)2]-, [FeIICl4]2-, or [CoIICl4]2-), in turn, determines how these dinuclear moieties are packed and spaced in a crystal structure. [RhI(H2bim)(CO)2][Cl] (1). In the crystal structure of 1, the dinuclear moiety found in the asymmetric unit consists of two [RhI(H2bim)(CO)2][Cl] units, shown in Figure 2. The Rh–Rh distance is 3.2986(4) Å. According to the literature, the typical bond length of RhI–RhI in a dimer, in which there are no supporting bridge ligands between metals, and with true covalent bonds, varies from 2.82 to 3.24 Å.32 The distance between Rh atoms in 1 is therefore too long to be considered as a true metal–metal bond but indicates clearly that interactions between metal atoms exist. In the examples presented in the literature, the distance between the two RhI centers is typically within a range of 3.25–3.68 Å8 in the stacked RhI chains that have no covalent metal–metal bonds but contain meaningful weak metal–metal interactions. The chloride counteranion is connected to the [RhI(H2bim)(CO)2]+ unit via hydrogen bonds, with N–Cl heavy-atom distances of 3.060(2)–3.137(2) Å. The dinuclear [RhI(H2bim)(CO)2]22+ units are connected with the neighboring dimers via weak RhI–π interactions in an extended 1D chain shown in Figure 3. In the solid state, the dinuclear RhI units can also interact with the neighboring dimers by weak interactions such as metal–π or π–π interactions, depending on the ligands available. The metal–metal distances in these contacts are longer than in the dinuclear unit. Typically, the metal–metal distance between the dinuclear units varies from 3.23 Å up to 3.93 Å.12 The average of the shortest Rh–C distances between the metal and the carbon atoms of the

Square-Planar [RhI(H2bim)(CO)2]2[A] Complexes

Crystal Growth & Design, Vol. 7, No. 12, 2007 2623

Figure 3. The weak metal–metal interactions between the dinuclear units (blue lines) of 1 with the shortest Rh–C distances (yellow lines) [1# ) (–x, 1 – y, –z); #2 ) (1 – x, 1 – y, –z); #3 ) (-x, -0.5 + y, -0.5 – z); #4 ) (1 – x, –y, –z)]. Figure 5. The thermal ellipsoid plot (50% probability level) of [Rh(H2bim)(CO)2][RhCl2(CO)2] (2).

Figure 4. Two staggered [RhI(H2bim)(CO)2]+ units.

Figure 6. Stacking of [RhI(H2bim)(CO)2]+ units and Rh2 and Rh2B chains.

neighboring H2bim in 1 is 3.69 Å, which is well within the range of the typical metal–π interactions reported in the literature. The neighboring chains are connected via weak chloride–hydrogen interactions, with heavy atom distances of C–Cl equal to 3.576(3)–3.658(3)Å.30 In the dinuclear unit [RhI(H2bim)(CO)2]+, the cations are staggered (Figure 4), which also allows additional π–π interactions between the H2bim ligands. The torsion angle N1–Rh1– Rh1B–N1B is 60.66(7)° (Figures 3 and 4). The orientation of the neighboring dinuclear units is antieclipsed; that is, the ligands are oriented in opposite directions and the torsion angle between the dinuclear system N1B–Rh1B–Rh1B(#2)–N1B(#2) (#2 ) 1 – x, 1 – y, –z) units is 180°. Each [RhI(H2bim)(CO)2]+ unit is planar. If the plane is defined by Rh–N–C–C–N, the planes within the dinuclear unit (in the asymmetric unit) are nearly coplanar, with an angle of 1.19(6)°, while they are coplanar between the dinuclear units. The average distance between the planes in the asymmetric unit is 3.298 Å, and between the symmetric systems, the distance is 3.371 Å. [RhI(H2bim)(CO)2]2[RhICl2(CO)2]2 (2). In the asymmetric unit of compound 2, there is again a dinuclear [RhI(H2bim)(CO)2]22+ cation and two [RhCl2(CO)2]- counteranions (Figure

5). Unlike in 1, three different RhI chains can be found in 2 (Figures 6 and 7). These three chains are linked together by weak N–H · · · Cl or C–H · · · Cl interactions.30 As in 1, the dinuclear units formed by [RhI(H2bim)(CO)2]+ cations interact with their neighbors by weak RhI–π interactions, forming a 1D chain or stack. The distance between the rhodium atoms within a dinuclear moiety of 2 is 3.2795(5) Å, and those between RhI and the closest carbons of the neighboring H2bim of the neighboring dimer are 3.504(5)–3.510(5) Å. Both of these contacts are somewhat shorter than in 1. In 2, the Rh–C and Rh–N bonds are eclipsed, as shown in Figure 6, although the H2bim and carbonyl ligands are not eclipsing. In 2, the anionic [RhICl2(CO)2]- units are also stacked, forming 1D chains of their own, as can be seen in Figures 6 and 7. In the anion chain labeled Rh2, in Figure 7, the Rh–C and Rh–N bonds are eclipsed, although the orientation of the CO and Cl ligands is opposed; that is, the [RhICl2(CO)2]- units are rotated 180 ° with respect to each other. In this chain, the RhI–RhI distances vary, and again, a dinuclear backbone with a RhI–RhI distance of 3.462(1) Å can be observed. The metal–metal distance between these dinuclear units is clearly

2624 Crystal Growth & Design, Vol. 7, No. 12, 2007

Jakonen et al. Table 3. Distances (Å) between [RhI(H2bim)(CO)2]+ Units in Complexes 3 and 4a

Rh1–Rh1B C6–C5B C5–C7(#1), C7–C5(#1) C6B–C6B(#2) C5B–C8B(#2)

3

4

3.3760(7) Å 3.412(9) Å 3.201(9) Å 3.374(8) Å 3.40(1) Å

3.3656(5) Å 3.393(6) Å 3.214(7) Å 3.361(6) Å 3.397(5) Å

a [3 #1(1 – x, 1 – y, –z); #2(–x, 1 –y, –z)], [4 #1(2 – x, 1 – y, 1 – z); #2(1 – x, 1 – y, 1 – z)].

Figure 7. The weak metal–metal interactions between the dinuclear units (blue lines) of 2 with the shortest Rh–C distances (yellow lines).

hydrogen bonds (Figure 8). The dinuclear units are further supported by π–π interactions between the H2bim ligands. In addition, weak H2bim π–π interactions exist between the neighboring dinuclear units. Unlike in 1 and 2, no clear metal–π interactions can be found in 3 or 4. The shortest contacts between the aromatic carbons in and between the dinuclear units are shown in Table 3 together with the Rh–Rh distances. In general, the C–C distances in complex 4 with cobalt are shorter than the corresponding ones in complex 3 containing iron. These π–π contacts between the symmetric units in compounds 3 and 4 are shorter than the distances between such units in compounds 1 and 2, where the interactions are π–metal contacts. Within the dinuclear unit of 3 and 4, the [RhI(H2bim)(CO)2]+ moieties are more or less staggered with a torsion angle N2–Rh1–Rh1B–N2B of 22.5(2)° and 23.0(2)° in 3 and 4, respectively. The orientation of the dinuclear units (the asymmetric units) is the opposite, with torsion angles of 180° between the symmetric units, that is, N2–Rh1–Rh1(#1)–N2(#1) and N2–Rh1–Rh1B(#2)–N2B(#2) [3 #1(1 – x, 1 – y, –z), #2(–x, 1 – y, –z); 4 #1(2 – x, 1 – y, 1 – z); #2(1 – x, 1 – y, 1 – z)]. The opposite orientation is caused by the location of the anion. Such an arrangement allows π–π interactions within and between the dinuclear units (Figure 10).

Figure 8. Thermal ellipsoid plot (50% probability level) of [Rh(H2bim)(CO)2]2[CoCl4] (4). Rh1–Rh1B 3.3656(5) Å, N3B–Cl1 3.122(4) Å, N4B–Cl1 3.340(4) Å, N4B–Cl2 3.314(5) Å, C7–Cl4 3.421(6) Å.

greater at 3.815(1) Å. Another [RhICl2(CO)2]- stack can also be found in the crystal structure of 2. In this chain (labeled Rh2B in Figure 7), the [RhICl2(CO)2]- units are separated by equal distances [3.616(1) Å]. Another difference between the chains Rh2 and Rh2B is that, in the latter, the [RhICl2(CO)2]- anions have a staggered orientation (Figure 7). [RhI(H2bim)(CO)2]2[FeIICl4] (3) and [RhI(H2bim)(CO)2]2 [CoIICl4] (4). The packing of the two isostructural complexes 3 and 4 is somewhat different from that of 1 and 3 owing to the anion. In 3 and 4, the tetrahedral geometry of the anion (FeCl42- in 3 or CoCl42- in 4) induces steric limitation in the packing. The crystal structure (the asymmetric unit) of 4 is shown in Figure 8. As in 1 and 2, the asymmetric unit of complexes 3 and 4 consists of a dinuclear [RhI(H2bim)(CO)2]22+ unit, Rh1, and Rh1B. The Rh–Rh distances are slightly greater in 3 and 4 than in 1 and 2 (Table 3) owing to the larger counteranion [MIICl4]2(M ) Fe in 3, and M ) Co in 4). The cations [RhI(H2bim)(CO)2]+ and the anion are held together by N–H · · · Cl

Figure 9. Interactions between symmetric units in complexes 3 and 4. The weak metal–metal interactions between the dinuclear units (blue lines) and the shortest π–π distances (gray lines) ([3 #1(1 – x, 1 – y, –z); #2(–x, 1 – y, –z)], [4 #1(2 – x, 1 – y, 1 – z); #2(1 – x, 1 – y, 1 – z)]).

Square-Planar [RhI(H2bim)(CO)2]2[A] Complexes

Crystal Growth & Design, Vol. 7, No. 12, 2007 2625

was even more emphasized when the spacing of the dinuclear units was compared. The order was 4 < 3 < 2 < 1. In all of the complexes, the interactions between the [RhI(H2bim)(CO)2]+ cations within the dinuclear units were supported by π–π interaction between the H2bim ligands. In 1 and 2, the dinuclear units were linked together by weak Rh–π interactions producing 1D chains. The larger anions in 3 and 4 prevented Rh–π interactions between the dinuclear [RhI(H2bim) (CO)2]22+ units, forcing the neighboring [RhI(H2bim)(CO)2]22+ moieties into the opposite orientation. As a result of such an arrangement, the neighboring dinuclear units interact by means of H2bim π–π interactions. Again, 1D chains were obtained.

Figure 10. Orientation of the dinuclear units in 3 and 4.

Acknowledgment. Financial support in the form of a grant [grant no. 210265 (MJ) and grant no. 110465 (LO)] provided by the Academy of Finland is gratefully acknowledged. The authors would also wish to thank Dr. Sari Suvanto for the ATRIR and EDS measurements and Taina Nivajärvi for the elemental analysis (EA) measurements. Supporting Information Available: Additional figures and tables for complexes 1–4 and CIF files for complexes 1–4. This material is available free of charge via the Internet at http://acs.pubs.org.

References

Figure 11. The location of anions in the planes.

One specific feature of the structure of compounds 3 and 4 is that the Rh–bim monomers form planes that are nearly parallel with the b axis of the unit cell. The counter anions, MCl42-, are located between every other plane, that is, between planes 2 and 3 and planes 4 and 5, as presented in Figure 11. In the near proximity of the dinuclear [RhI(H2bim)(CO)2]22+ unit, there are four MIICl42- cations within a short distance of each other. It can also be seen that one MIICl42- is surrounded by seven [RhI(bim)(CO)2]+ units.30 Conclusion Four square-planar ionic carbonyl-containing RhI complexes of type [RhI(H2bim)(CO)2]n[A] (A ) [Cl]- (1), [RhCl2(CO)2](2), [FeCl4]2- (3), and [CoCl4]2- (4)) were synthesized by means of the reductive carbonylation of RhCl3 in the presence of a sacrificial metal surface (Fe or Co) and H2bim. In solution, the properties of the [RhI(H2bim)(CO)2]+ are similar in all complexes owing to the fact that complexes 1–4 are essentially mononuclear compounds. However, in their solid state, interaction between these cationic units could be observed. It was found that, in all of the complexes, the [Rh(H2bim)(CO)2]+ cations formed dinuclear systems. The metal–metal interactions within these dinuclear units, and especially between the neighboring dinuclear units, were dependent on the anion. The RhI–RhI distances increased in the order [RhI(H2bim)(CO)2]2 [RhICl2(CO)2]2 2 < [RhI(H2bim)(CO)2]2[Cl]2 1 < [RhI(H2bim)(CO)2]2[CoIICl4] 4 < [RhI(H2bim)(CO)2]2[FeIICl4] 3. This clearly reflects the steric requirements set by the tetrahedral MIICl42 anions. A similar trend

(1) (a) Miller, J. S. Extended Linear Chain Compounds; Plenum Press: New York, 1982; Vols. 1–3. (b) Bera, J. K.; Dunbar, K. R. Angew. Chem., Int. Ed. 2002, 23, 4453 . (2) (a) See for example: Dockum, B. W.; Reiff, W. M. Inorg. Chem. 1982, 21, 391. (b) Dockum, B. W.; Eisman, G. A.; Witten, E. H.; Reiff, W. M. Inorg. Chem. 1983, 22, 150. (3) (a) Houlding, V. H.; Miskowski, V. M. Coord. Chem. ReV. 1991, 111, 145. (b) Yam, V. W.-W.; Wong, K. M.-C.; Zhu, N. J. Am. Chem. Soc. 2002, 124, 6506. (c) Cocker, N. L.; Krause Bauer, J. A.; Elder, R. C. J. Am. Chem. Soc. 2004, 126, 12. (4) (a) Tanaka, K.; Morimoto, M.; Tanaka, T. Chem. Lett. 1983, 901. (b) Haukka, M.; Kiviaho, J.; Ahlgrén, M.; Pakkanen, T. A. Organometallics 1995, 14, 825. (c) Luukkanen, S.; Homanen, P.; Haukka, M.; Pakkanen, T. A.; Deronzier, A.; Chardon-Noblat, S.; Zsoldos, D.; Ziessel, R. Appl. Catal., A 1995, 185, 157. (d) Haukka, M.; Venäläinen, T.; Kallinen, M.; Pakkanen, T. A. J. Mol. Catal. A: Chem. 1998, 136, 127. (e) Moreno, M. A.; Haukka, M.; Venäläinen, T.; Pakkanen, T. A. Catal. Lett. 2004, 96 (3–4), 153. (5) (a) Ishida, H.; Tanaka, K.; Tanaka, T. Chem. Lett. 1985, 3, 405. (b) Ishida, H.; Tanaka, H.; Tanaka, K; Tanaka, T. Chem. Lett. 1987, 4, 1035. (c) Collomb-Dunand-Sauthier, M.-N.; Deronzier, A.; Ziessel, R. Inorg. Chem. 1994, 33, 2961. (d) Chardon-Noblat, S.; Deronzier, A.; Hartl, F.; van Slageren, J.; Mahabiersig, T. Eur. J. Inorg. Chem. 2001, 613. (6) (a) Jääskeläinen, S.; Suomalainen, P.; Haukka, M.; Riihimäki, H.; Pursiainen, J. T.; Pakkanen, T. A. J. Organomet. Chem. 2001, 633, 69. (b) Barkley, J. V.; Heaton, B. T.; Jacob, C.; Mageswaran, R.; Sampanther, J. T. J. Chem. Soc., Dalton Trans. 1998, 697. (7) (a) Chern, S.-S.; Lee, G.-H.; Peng, S.-M. Chem. Commun. 1994, 1645. (b) Finniss, G. M.; Candall, E.; Campana, C.; Dunbar, K. R. Angew. Chem., Int. Ed. 1996, 35, 2772. (c) Mitsumi, M.; Goto, H.; Umebayashi, S.; Ozawa, Y.; Kobayashi, M.; Yokoyama, T.; Tanaka, H.; Kuroda, S.; Toriumi, K. Angew. Chem., Int. Ed. 2005, 44, 4164. (8) (a) Huq, F.; Skapaski, A. C. J. Cryst. Mol. Struct. 1974, 4, 411. (b) Decker, M. J.; Fjeldsted, D. O. K.; Stobart, S. R.; Zaworotko, M. J. Chem. Commun. 1983, 1525. (c) Crotti, C.; Cenini, S.; Rindone, B.; Tollari, S.; Demartin, F. Chem. Commun. 1986, 784. (d) Villacorta, G. M.; Lippard, S. J. Inorg. Chem. 1988, 27, 144. (e) Matsubayashi, G.; Yokoyama, K.; Tanaka, T. J. Chem. Soc., Dalton Trans. 1988, 253. (f) Oro, L. A.; Pinillos, M. T.; Tejel, C.; Apreda, M. C.; FocesFoces, C.; Cano, F. H. J. Chem. Soc., Dalton Trans. 1988, 1927. (g) Pursiainen, J.; Teppana, T.; Rossi, S.; Pakkanen, T. A. Acta Chem. Scand. 1993, 47, 416. (h) Ragaini, F.; Pizzotti, M.; Cenini, S.; Abbotto, A.; Pagain, G. A.; Demartin, F. J. Organomet. Chem. 1995, 489, 107. (i) Elduque, A.; Finestra, C.; Lopéz, J. A.; Lahoz, F. J.; Merchan, F.; Oro, L. A.; Pinillos, M. T. Inorg. Chem. 1998, 37, 824. (j) Pruchnik, F. P.; Jakimowicz, P.; Ciunik, Z. Inorg. Chem. Commun. 2001, 4, 726. (k) Kiriakidou-Kazemifar, N. K.; Haukka, M.; Pakkanen, T. A.; Tunik, S. P.; Nordlander, E. J. Organomet. Chem. 2001, 623, 65. (l)

2626 Crystal Growth & Design, Vol. 7, No. 12, 2007

(9)

(10) (11) (12)

(13) (14)

(15)

Torralba, M. C.; Cano, M.; Campo, J. A.; Heras, J. V.; Pinilla, E.; Torres, M. R. J. Organomet. Chem. 2001, 633, 91. (m) Cotton, F. A.; Dikarev, E. V.; Petrukhina, M. A. J. Organomet. Chem. 2002, 596, 130. (a) Grey, R. A.; Anderson, L. R. Inorg. Chem. 1977, 16, 12–3187. (b) Beveridge, K. A.; Bushnell, G. W.; Stobart, S. R.; Atwood, J. L.; Zaworotko, M. J. Organometallics 1983, 2, 1447. (c) del Rosario Benites, M.; Fronczek, F. R.; Hammer, R. P.; Maverick, A. W. Inorg. Chem. 1997, 36, 5826. (d) Cotton, F. A.; Dikarev, E. V.; Petrukhina, M. A. J. Chem. Soc., Dalton Trans. 2000, 4241. (a) Schurig, V.; Pille, W.; Winter, W. Angew. Chem., Int. Ed. 1983, 22, 327. (b) Heyduk, A. F.; Krodel, D. J.; Meyer, E. E.; Nocera, D. G. Inorg. Chem. 2002, 41, 634. Berry, J. F.; Cotton, F. A.; Huang, P.; Murillo, C. A.; Wang, X. Dalton Trans. 2005, 3713. (a) Doendes, R. J. Inorg. Chem. 1978, 17, 1315. (b) DeHaeven, P. W.; Goedken, V. L. Inorg. Chem. 1979, 18, 827. (c) Yamamoto, Y.; Wakatsuki, Y.; Yamazaki, H. Organometallics 1983, 2, 1604. (d) Cotton, F. A.; Shiu, K.-B. ReV. Chem. Miner. 1986, 23, 14. (e) Cotton, F. A.; Shiu, K.-B. ReV. Chem. Miner. 1986, 23, 14. (f) Sheldrick, W. S.; Bell, P. Inorg. Chim. Acta 1987, 137, 181. (g) Sheldrick, W. S.; Gunther, B. Inorg. Chim. Acta 1988, 151, 237. (h) Corradi, E.; Masciocchi, N.; Palyi, G.; Ugo, R.; Vizi-Orosz, A.; Zucchi, C.; Sironi, A. J. Chem. Soc., Dalton Trans. 1997, 4651. (i) Elduque, A.; Garces, Y.; Lahoz, F. J.; Lopéz, J. A.; Oro, L. A.; Pinillos, T.; Tejel, C. Inorg. Chem. Commun. 1999, 2, 214. (j) Mochida, T.; Torigoe, R.; Koinuma, T.; Asano, C.; Satou, T.; Koike, K.; Nikaido, T. Eur. J. Inorg. Chem. 2006, 558. Allen, F. H. Acta Crystallogr., Sect. B 2002, 58, 380. (a) Sang, R.; Zhu, M.; Yang, P. Acta Crystallogr., Sect. E 2002, 58, m172. (b) van Albada, G. A.; Mohamadou, A.; Lanfredi, A. M. M.; Mutikainen, I.; Turpeinen, U.; Ugozzolli, F.; Reedijk, J. Z. Anorg. Allg. Chem. 2004, 630, 1594. (c) Drew, M. G. B.; Felix, V.; Goncavales, I. S.; Kuhn, F. E.; Lopez, A. D.; Romao, C. C. Polyhedron 1998, 17, 1091. (d) Panda, B. K.; Sengupta, S.; Chakravorty, A. Eur. J. Inorg. Chem. 2004, 178. (e) Dupont, J.; Ebeling, G.; Delgado, M. R.; Consorti, C. S.; Burrow, R.; Farrar, D. H.; Lough, A. J. Inorg. Chem. Commun. 2001, 4, 471. (f) de Souza Lemos, S.; Bessler, K. E.; Schulz Lang, E. Z. Anorg. Allg. Chem. 1998, 624, 30. (g) Ye, B.-H.; Ding, B.-B.; Weng, Y.-Q. Cryst. Growth. Des. 2005, 5, 801. (h) Rau, S.; Gorls, H. J. Coord. Chem. 2004, 57, 1587. (i) Esteruelas, M. A.; Lahoz, F. J.; Oro, L. A.; Onate, E.; Ruiz, N. Inorg. Chem. 1994, 33, 787. (j) Ziessel, R.; Youinou, M.-T.; Balegroune, F.; Grandjean, D. J. Organomet. Chem. 1992, 441, 143. (k) Mahjoub, A. R.; Ramazani, A.; Morsali, A. Z. Kristallogr.––New Cryst. Struct. 2003, 218, 435. (a) Dance, I. G.; Abushamleh, A. S.; Goodwin, H. A. Inorg. Chim. Acta 1980, 43, 217. (b) Haj, M. A.; Quiros, M.; Salas, J. M. J. Chem. Cryst. 2004, 34, 549. (c) Ye, B.-H.; Ding, B.-B.; Weng, Y.-Q.; Chen,

Jakonen et al.

(16) (17)

(18)

(19)

(20)

(21) (22) (23)

(24) (25) (26) (27) (28) (29)

(30) (31) (32)

X.-M. Inorg. Chem. 2004, 43, 6866. (d) Maiboroda, A.; Rheinwald, G.; Lang, H. Eur. J. Inorg. Chem. 2001, 2263. ¨ hrstro¨m, L. CrystEngComm 2003, 5, 222. Larsson, K.; O (a) Bencini, A.; Mani, F. Inorg. Chim. Acta 1988, 215, 154. (b) Gao, X.-L.; Wei, Y.-B.; Li, Y.-P.; Yang, P. Acta Crystallogr., Sect. C 2005, 61, m10. (a) Kaiser, S. W.; Saillant, R. B.; Butler, W. M.; Rasmussen, P. G. J. Am. Chem. Soc. 1975, 97, 425. (b) Kaiser, S. W.; Saillant, R. B.; Butler, W. M.; Rasmussen, P. G. Inorg. Chem. 1976, 15, 11–2681. (c) Kaiser, S. W.; Saillant, R. B.; Butler, W. M.; Rasmussen, P. G. Inorg. Chem. 1976, 15, 11–2688. (a) Oro, L. A.; Carmona, D.; Lamata, M. P.; Tiripicchio, A.; Lahoz, F. J. J. Chem. Soc., Dalton Trans. 1986, 15. (b) García, M. P.; López, A. M.; Esteruelas, M. A.; Lahoz, F. J.; Oro, L. A. J. Chem. Soc., Dalton Trans. 1990, 3465. (c) García, M. P.; Jiménez, M. V.; Oro, L. A. J. Organomet. Chem. 1992, 438, 229. Otwinowski, Z.; Minor, W. Processing of X-ray Diffraction Data Collected in Oscillation Mode. In Methods in Enzymology, Volume 276, Macromolecular Crystallography, Part A; Carter, C. W., Sweet, J., Eds.; Academic Press: New York, 1997; pp 307–326. Duisenberg, A. J. M.; Kroon-Batenburg, L. M. J.; Schreurs, A. M. M. J. Appl. Crystallogr. 2003, 36, 220–229. Sheldrick, G. M. SHELXS-97, Program for Crystal Structure Determination; University of Göttingen: Göttingen, Germany, 1997. Burla, M. C.; Camalli, M.; Carrozzini, B.; Cascarano, G. L.; Giacovazzo, C.; Polidori, G.; Spagna, R. J. Appl. Crystallogr. 2005, 38, 381–388. Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837. Sheldrick, G. M. SADABS - Bruker Nonius scaling and absorption correction, V 2.10; Bruker AXS, Inc.: Madison, WI, 2003. Sheldrick, G. M. SHELXTL V. 6.14-1, Bruker Analytical X-ray Systems; Bruker AXS, Inc.: Madison, WI, 2005. Sheldrick, G. M. SHELXL-97, Program for Crystal Structure Refinement; University of Göttingen: Göttingen, Germany, 1997. Xiao, J.-C.; Shreeve, J. M. J. Org. Chem. 2005, 70, 3072. (a) Haukka, M.; Jakonen, M.; Nivajärvi, T.; Kallinen, M. Dalton Trans. 2006, 3212. (b) Jakonen, M.; Hirva, P.; Nivajärvi, T.; Kallinen, M.; Haukka, M. Eur. J. Inorg. Chem. 2007, 3497. See electronic Supporting Information. Usón, R.; Oro, L. A.; Carmona, D; Lamata, M. P. Transitition Met. Chem. (Dordrecht, Neth.) 1981, 6, 372 . (a) Cheng, S.-S.; Liaw, M.-C.; Peng, S.-M. Chem. Commun. 1993, 359. (b) Chern, S.-S.; Lee, G.-H.; Peng, S.-M. Chem. Commun. 1994, 1645. (c) Mizumi, M.; Umebayashi, S.; Ozawa, Y.; Tadokoro, M.; Kawamura, H.; Toriumi, K. Chem. Lett. 2004, 33, 970.

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