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Searching the CSD for Ru(II)-Cl complexes containing a phosphine/thioether ligand(s) resulted in numerous hits, but limiting the results so the metal center also contained a para-cymene (p-Cy) ligand resulted in just five

complexes. Of the five complexes, there are three different backbones, which are shown in Figure 7-5.10-13 This figure shows the cationic portions of the five known Ru(II)-Cl complexes with the general formula [(η6-p-Cy)Ru(L)Cl]X. The

ligand in 7.9 contains a dimethylene linker between the phosphine and thioether

127 P S Ru Cl (7.11) (7.10a, b) R (7.9a, b) P S(O) Ru Cl P S Ru Cl O 2

Figure 7-5. The cationic portions of five known Ru(II)-Cl complexes with the general formula [(η6-p-Cy)Ru(L)Cl]X. On the left 7.9, where a, R = Me and b,

R = Et. In the center, 7.10, where a contains a thioether and in b, the thioether is oxidized. On the right, only half of 7.11 is pictured, the complex contains

(in a, R is a methyl group; in b, R is an ethyl group). The ligand in 7.10 contains a cyclohexene backbone (in 7.10b, the thioether is oxidized). Only half of 7.11 is pictured. This complex contains two Ru(II) metal centers ligated by a single ligand. The ligand is linked by a dimethylene bridge linking two thioethers.

To add to this set, 7.5 has the formula [(η6-p-Cy)Ru(7.1)Cl]Cl and consists

of a mononuclear ruthenium(II) metal center ligated by a chloride ion, η6-para-

cymene (p-Cy), and 7.1, with an outer-sphere chloride ion. The cationic portion of

this complex is show in Figure 7-6. The complex crystallizes with one molecule of acetone (OC(CH3)2) in a monoclinic unit cell (P21/n, R1 = 11.26%).

Refinement details are contained in Appendix 1.

Figure 7-6. A structural representation of the cationic portion of 7.5.

7.3.1. Metal Center Environment

Distinctive characteristics of the Ru(II) metal center can be found by comparing the crystal structure of 7.5 with those in compounds 7.9a and 7.11. All of the compounds have similar environments around the metal center of [(η6-p-

Cy)Ru(L)Cl]+, where L = etdmp (7.9a) or dppte (7.11) (Figure 7-5).10, 13 128

The three ligands, 7.1, etdmp, and dppte, have neutral phosphine and thioether donor atoms, however, etdmp has a slightly more flexible and smaller backbone. The flexible backbone of 7.9a was used in a study to help understand the hemilability of bidentate P/S ligands.10 Dppte, in 7.11, has the same size ring as 7.1 upon coordination to the Ru(II) metal center, but the backbone is, again, slightly more flexible. It must also be noted that dppte has two coordination sites and ligates to two ruthenium(II) metal centers, but that both of these metal centers are effectively identical. The bond lengths and angles around the metal centers of 7.5, 7.9a, and 7.11 are shown in Table 7-3.

Each Ru(II) center forms a characteristic “piano stool” geometry by coordinating a chloride anion, a neutral η6-para-cymene ligand, and a bidentate

P/S donor ligand (FKW99-0-3 (7.5), etdmp (7.9a), and dppte (7.11)). The Ru-Cl bond distances are similar and increase from 2.3914(13) Å in 7.11 to 2.396(2) Å in 7.5 to 2.403(1) Å in 7.9a (Table 7-3). In each complex, the p-Cy ligand forms

an η6-bond with the metal center. The range of Ru(I)-(p-Cy) bond distances

overlap in 7.5, 7.9a, and 7.11.

Table 7-3. Selected bond lengths (Å) and angles (°) for 7.5, 7.9a, and 7.11.

7.5 7.9a10 _7.1113 Ru(1) - Cl(1) 2.396(2) 2.403(1) 2.3914(13) Ru(1) - P(1) 2.319(2) 2.313(1) 2.3255(13) Ru(1) - S(1) 2.356(2) 2.377(1) 2.3592(11) Ru(1) - p-Cy 2.234(9)-2.275(8) 2.198(3)-2.273(3) 2.218(4)-2.282(5) P(1)-Ru(1)-S(1) 80.22(8) 84.52(4) 80.80(4) P(1)-Ru(1)-Cl(1) 89.03(9) 86.68(4) 87.74(4) S(1)-Ru(1)-Cl(1) 89.61(8) 90.89(4) 89.59(4)

The Ru(1)-P(1) bond distance is similar in 7.5 and 7.9a, but is longer in 7.11. The Ru(1)-S(1) distance is similar in 7.5 and 7.11, but slightly longer in 7.9a. In each case, however, the Ru(1)-P(1) distance is shorter than the Ru(1)-S(1) distance, likely caused by the differing soft/hard donor properties of the phosphine and thioether atoms.

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Since the ligand backbones are of differing flexibilities, it is interesting to compare their bite angles. The P(1)-Ru(1)-S(1) angle in 7.5 (80.22(8)°) is very

similar to 7.11 (80.80(4)°), which is expected since the chelate ring is the same size. The same angle in 7.9a (84.52(4)°) is the largest of the three complexes, which is interesting since 7.9a has the smallest chelate ring; however, the etdmp ligand possesses the most flexible backbone of the three. The P(1)-Ru(1)-Cl(1) angle is the largest in 7.5 (89.03(9)°) and is the smallest in 7.9a (86.52(4)°). In 7.11, this angle is 87.74(4)°. The S(1)-Ru(1)-Cl(1) angle is close to 90° in all three complexes.

7.3.2. Ligand Environment

The structural distortions of 7.1, when bound to a ruthenium(II) metal center (as in 7.5), can also be compared (Table 7-4). The P(1)…S(1) distance is slightly shorter when bound in 7.5 (3.013(3) Å) than in the free ligand 7.1 (3.0339(13) Å). It is interesting to note that the P(1)…S(1) distance in 7.11 (3.04(1) Å) is most similar to 7.1 and, therefore, is slightly larger than the P…S

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Table 7-4. Selected bond lengths (Å) and angles (°) for 7.1 and 7.5. 7.1 7.5 P(1)…S(1) 3.0339(13) 3.013(3) P(1) - C(1) 1.850(3) 1.816(10) S(1) - C(9) 1.784(3) 1.829(10) P(1)-C(1)-C(2) 118.0(2) 116.4(7) P(1)-C(1)-C(10) 124.1(2) 124.9(7) S(1)-C(9)-C(8) 115.1(2) 115.5(7) S(1)-C(9)-C(10) 123.8(2) 121.3(7) C(2)-C(1)-C(10) 117.8(3) 118.7(9) C(10)-C(9)-C(8) 121.0(3) 122.9(9) C(1)-C(10)-C(9) 126.4(3) 127.7(9) C(4)-C(5)-C(10)-C(1) -1.2(4) -0.1(9) C(6)-C(5)-C(10)-C(9) 0.1(3) -5.4(11) C(4)-C(5)-C(10)-C(9) -179.5(3) 177.5(7) C(6)-C(5)-C(10)-C(1) 178.5(3) 176.9(7) Mean Plane Deviations

P(1) 0.018(5) -0.096(11)

S(1) 0.136(5) 0.217(11)

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distance in 7.5. This is surprising since the ligands form the same size chelate ring and have similar bite angles; however, the ligand in 7.11 is slightly more flexible and has more steric bulk in the dimer, which could cause it to distort more than 7.1 upon complexation. The P(1)…S(1) distance in 7.9a (3.15(1) Å) is much larger than in the other three compounds. This is consistent with the larger observed P(1)-Ru(1)-S(1) angle and the more flexible backbone, however, it is counterintuitive since the chelate ring is smaller.

The P(1)-C(1) bond distance is smaller in 7.5 than in 7.1. In contrast, the S(1)-C(9) bond distance is much smaller in 7.1 than in 7.5.

The in-plane deviations of the outer P(1)-C(1)-C(2) angle in 7.5 is smaller than the same angle in 7.1, where the S(1)-C(9)-C(8) angle is similar in both compounds. The inner P(1)-C(1)-C(10) angle is slightly bigger in 7.5 than in 7.1, but the S(1)-C(9)-C(10) is much smaller in 7.5 than in 7.1.

The out-of-plane deviations of P(1) and S(1) are larger in 7.5 than in 7.1. Additionally, the ruthenium ion in 7.5 lies -1.2837(136) Å from the naphthalene plane. Lastly, the naphthalene ring distortions of the angles C(2)-C(1)-C(10), C(1)-C(10)-C(9) and C(10)-C(9)-C(8) are larger in 7.5 than in 7.1. The large p-Cy

ligand in 7.5 may be sterically crowding the bidentate ligand, causing some of these distortions