Supporting Information for Spin Transition and Structural Transformation in a Mononuclear Cobalt(II) Complex Ying Guo, Xiu-Long Yang, Rong-Jia Wei, Lan-Sun Zheng, and Jun Tao* State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People s Republic of China Tel: 86-592-2188138; Fax: 86-592-2183047. E-mail: taojun@xmu.edu.cn. S1
Contents Materials and Synthesis S3 Characterization and Methods S3 Table S1. Crystal Data and Structure Refinements for compounds 2 and 3 S6 Table S2. Selected bond lengths and bond angles for compound 2 HT S7 Table S3. Selected bond lengths and bond angles for compound 2 LT S7 Table S4. Selected bond lengths and bond angles for compound 3 S8 Table S5. Hydrogen bonds and C H π interactions for compounds 2 HT and 2 LT in the ab plane S8 Figure S1. ORTEP diagram of the structural unit of 2 HT S9 Figure S2. ORTEP diagram of the structural unit of 2 LT S9 Figure S3. ORTEP diagram of the structural unit of 3 S10 Figure S4. Intermolecular interactions of 2 HT in the ab plane S10 Figure S5. Intermolecular interactions of 2 LT in the ab plane S11 Figure S6. Intermolecular interactions of 3 in the ac plane S11 Figure S7. Intermolecular interactions of 2 HT in the bc plane S12 Figure S8. Intermolecular interactions of 2 LT in the bc plane S12 Figure S9. Magnetic properties of compound 2. Applied field: 5000 Oe, sweeping rate: 1 K min 1 S13 Figure S10. Magnetic properties of compound 3. Applied field: 5000 Oe, sweeping rate: 1 K min 1 S13 Figure S11. DSC trace for complex 2 upon cooling and warming S14 Figure S12. DSC trace for methanol upon cooling and warming S14 Figure S13. IR spectrum of compound 2 S15 Figure S14. IR spectrum of compound 3 S15 S2
Experimental Section Materials. CoCl 2 6H 2 O, KPF 6, 4 -(4 -pyridyl)-2,2 :6,2 -terpyridine (pyterpy), dichloromethane and methanol were purchased from commercial sources and used as received. Synthesis. Method 1) A CH 2 Cl 2 solution (5 ml) of pyterpy (0.0310 g, 0.1 mmol) was added dropwise to MeOH solution (5 ml) of CoCl 2 6H 2 O (0.0119 g, 0.05 mmol) and KPF 6 (0.0184 g, 0.1 mmol) at room temperature, the resulting red solution were sealed and left undisturbed for 5-7 days. Red block crystals of compound 2 and black block crystals of compound 3 suitable for X-ray diffraction analysis were separated and collected by hand. Method 2) A CH 2 Cl 2 solution (5 ml) of pyterpy (0.0620 g, 0.2 mmol) was added dropwise to MeOH solution (10 ml) of CoCl 2 6H 2 O (0.0238 g, 0.1 mmol) and KPF 6 (0.0368 g, 0.2 mmol) at room temperature, the resulting red solution were sealed and left undisturbed for 5-7 days. Red block crystals of compound 2 (without by-product 3) were collected by filtration. Structural transformation. During the synthesis of compounds 2 and 3 (method 1), the crystals of 2 and 3 were left undisturbed in the mother liquor for 3-4 weeks, all crystals of 2 were transformed to crystals of 3. Elemental analysis. Compounds 2 and 3 were unstable in air due to the loss of guest solvent molecules, so elemental analyses were conducted on the desolvated samples. Compounds 2 and 3 were heated at 50 C under vacuum for 48 h. Calcd (%) for the solvent-free sample of 2, C 40 H 28 N 8 P 2 F 12 Co: N, 11.56; C, 49.55; H, 2.91. Found: N, 11.70; C, 49.36; H, 2.95. IR (KBr pellet, cm 1 ) of 2: 3440(s, br), 1620(m), 1598(m), 1572(w), 1542(w), 1473(w), 1429(w), 1410(m), 1385(w), 1248(w), 1165(w), 1120(w), 836(vs), 793(w), 562(m). Calcd (%) for the solvent-free sample of 3, C 40 H 28 N 8 P 2 F 12 Co: N, 11.56; C, 49.55; H, 2.91. Found: N, 11.62; C, 49.43; H, 2.85. IR (KBr pellet, cm 1 ) of 3: 3433(s, br), 1618(m), 1598(m), S3
1543(w), 1469(w), 1408(w), 1376(m), 1076(w), 840(s), 793(w), 562(w). Physical techniques. Elemental analyses (C, H, N) were obtained using PerkinElmer 240Q elemental analyzer. IR spectra (KBr pellets) were recorded on a Nicolet 5DX spectrophotometer in the range of 400 4000 cm 1. X-ray crystallographic data collection and structure refinement. Single-crystal XRD data were recorded on Agilent SuperNova CCD diffractometer. The structures were solved by direct methods and refined on F 2 by anisotropic full-matrix least-squares methods using SHELXTL-97. 1 All non-hydrogen atoms were refined anisotropically, while hydrogen atoms were generated by the riding mode. (1) Sheldrick, G. M. SHELXS-97: Programs for crystal structure analysis, University of Göttingen, Göttingen (Germany), 1997. Magnetic measurements. Magnetic measurements were performed on freshly isolated samples and were carried out at a sweeping rate of 1 K min 1 on a Quantum Design SQUID XL7 magnetometer. The sample of compound 2 and a drop of methanol were sealed in a quartz tube. Magnetic susceptibilities were calibrated with the sample holder, and diamagnetic corrections were estimated from Pascal s constants. Differential Scanning Calorimetry (DSC) DSC (differential scanning calorimetry) measurement on compound 2 was performed by cooling and heating the sample (3.315mg), instilled a drop of methanol in an aluminum crucible using a NETZSCH DSC 200F3. The measurement was carried out at 10 K min 1 sweeping rate under nitrogen in the temperature range of 170 210 K. We also measured a drop of methanol in an aluminum crucible under the same condition. From the Figure s11, we found an endothermic peak at 189 K during the warming process and an exothermic peak at 180 K during the cooling process. The DSC data indicated that the complex exhibited a reversible phase transition with a 9 K hysteresis. Figure s12 showed that pure methanol did not have either endothermic or exothermic S4
peak in the temperature range of 170 210 K. It meant that methanol dropped in the sample did not affect the DSC data of the sample. Therefore, we could use the DSC data to estimate the enthalpy and entropy associated with the SCO and crystallographic phase transition upon heating, which are 4.99 kj mol 1 and 26.38 J mol 1 K 1, respectively. S5
Tables Table S1. Crystal Data and Structure Refinements for compounds 2 and 3. 2 2 3 Temperature / K 250(2) 100(2) 173(2) Empirical formula C 34 H 36 CoF 12 N 8 O 2 P 2 C 34 H 36 CoF 12 N 8 O 2 P 2 C 43 H 36 Cl 4 CoF 12 N 8 OP 2 Mr / g mol 1 1033.66 1033.66 1171.47 Crystal system monoclinic monoclinic orthorhombic Space group C2/c P2 1 /c Pbca a / Å 19.8091(10) 18.1455(6) 21.436(4) b / Å 27.1281(8) 26.7653(9) 17.631(4) c / Å 8.5796(3) 8.6418(3) 25.446(5) β / 111.740(4) 93.208(3) V / Å 3 4282.6(3) 4190.5(2) 9617(3) Z 4 4 8 D cald / g cm 3 1.603 1.638 1.618 F(000) 2100 2100 4728 Index ranges 22 h 18 17 h 20 27 h 27 19 h 30 28 h 30 22 h 18 9 h 9 7 h 9 32 h 33 Reflections collected 6387 13422 89666 Data / restraints / parameters 3165 / 0 / 307 6557 / 0 / 604 10993 / 0 / 640 Goodness-of-fit on F 2 1.079 1.132 1.065 Final R indices [I > 2σ (I)] 0.0855 0.0800 0.0496 R indices (all data) 0.2588 0.2098 0.1463 S6
Table S2. Selected bond lengths and bond angles for compound 2 HT. Bond lengths of Co in 2 HT Bond angles of Co in 2 HT Co1 N1 2.132(4) N1 Co1 N2 76.76(2) Co1 N2 2.008(6) N1 Co1 N4 91.05(2) Co1 N4 2.123(4) N1 Co1 N5 103.24(2) Co1 N5 2.023(6) N2 Co1 N4 102.87(1) N2 Co1 N5 180.00(0) N4 Co1 N5 77.13(1) N1 Co1 N1# 153.52(1) N1 Co1 N4# 94.80(1) N4 Co1 N4# 154.26(1) #) x + 2, y, z + 3/2. Table S3. Selected bond lengths and bond angles for compound 2 LT. Bond lengths of Co in 2 LT Bond angles of Co in 2 LT Co1 N1 2.153(5) N1 Co1 N2 78.17(1) Co1 N2 1.940(5) N1 Co1 N3 156.78(1) Co1 N3 2.146(5) N1 Co1 N5 93.89(1) Co1 N5 1.998(5) N1 Co1 N6 102.81(1) Co1 N6 1.877(5) N1 Co1 N7 90.57(1) Co1 N7 2.013(4) N2 Co1 N3 78.61(1) N2 Co1 N5 98.45(1) N2 Co1 N6 178.62(1) N2 Co1 N7 100.34(1) N3 Co1 N5 89.93(1) N3 Co1 N6 100.42(1) N3 Co1 N7 93.14(1) N5 Co1 N6 80.53(1) N6 Co1 N7 80.67(1) S7
Table S4. Selected bond lengths and bond angles for compound 3. Bond lengths of Co in 3 Bond angles of Co in 3 Co1 N1 2.062(2) N1 Co1 N2 80.10(8) Co1 N2 1.903(2) N1 Co1 N3 159.53(7) Co1 N3 2.065(2) N1 Co1 N5 95.06(8) Co1 N5 2.082(2) N1 Co1 N6 97.56(8) Co1 N6 1.909(2) N1 Co1 N7 89.58(8) Co1 N7 2.065(2) N2 Co1 N3 79.43(8) N2 Co1 N5 102.00(8) N2 Co1 N6 177.30(9) N2 Co1 N7 98.59(8) N3 Co1 N5 89.30(8) N3 Co1 N6 102.90(8) N3 Co1 N7 93.34(9) N5 Co1 N6 79.49(8) N6 Co1 N7 79.98(8) Table S5. Hydrogen bonds and C H π interactions for compounds 2 HT and 2 LT in the ab plane. 2 HT 2 LT O1 F2 3.163(1) O1 F7 3.020(1) O1 F3 3.131(1) O1 F12 3.031(1) C F1 3.389(1) O2 F3 2.966(1) C F3 3.377(1) O2 F6 3.046(1) C H π 3.873(1) C F3 3.259(1) C F4 3.255(1) C F9 3.332(1) C F12 3.291(1) C H π 3.735(1)/ 3.742(1) S8
Figures Figure S1. ORTEP diagram of the structural unit of 2 HT. A) x + 2, y, z + 3/2. Figure S2. ORTEP diagram of the structural unit of 2 LT. S9
Figure S3. ORTEP diagram of the structural unit of 3. Figure S4. Intermolecular interactions of 2 HT in the ab plane. S10
Figure S5. Intermolecular interactions of 2 LT in the ab plane. Figure S6. Intermolecular interactions of 3 in the ac plane. S11
Figure S7. Intermolecular interactions of 2 HT in the bc plane. V) offset π π interactions: C centroid = 3.853(1) Å VI) offset π π interactions: centroid centroid = 3.572(1) Å VII) offset π π interactions: N centroid = 4.291(1) Å C centroid = 4.292(1) Å Figure S8. Intermolecular interactions of 2 LT in the bc plane. VI) offset π π interactions: C centroid = 3.812(1)/3.821(1) Å VII) offset π π interactions: centroid centroid = 3.555(1) Å VIII) offset π π interactions: N centroid = 4.213(1)/4.469(1) Å C centroid = 4.263(1)/4.388(1) Å S12
Figure S9. Magnetic properties of compound 2. Applied field: 5000 Oe, sweeping rate: 1 K min 1. 2.5 χ M T / cm 3 K mol -1 2.0 1.5 1.0 complex 2 0.5 100 150 200 250 300 T / K Figure S10. Magnetic properties of compound 3. Applied field: 5000 Oe, sweeping rate: 1 K min 1. Temperature sequence: 300-2-380-2-380 K. 1.5 χ M T / cm 3 K mol -1 1.0 0.5 300-2 K 2-380 K 380-2 K 2-380 K 0.0 0 50 100 150 200 250 300 350 400 T / K S13
Figure S11. DSC trace for compound 2 upon cooling and warming (10 K min 1 ). 0.8 Heat flow / mw 0.4 0.0-0.4-0.8 heating cooling -1.2 170 175 180 185 190 195 200 205 210 T / K Figure S12. DSC trace for methanol upon cooling and warming (10 K min 1 ) in the temperature range for compound 2 in order to rule out possible contribution from liquid methanol during spin transition and phase transition. 2 1 Heat flow / mw 0-1 -2 170 180 190 200 210 T / K S14
Figure S13. Infrared spectrum of compound 2. 100 Transmittance \% 95 90 85 3440 1572 1542 1473 1429 1620 1598 1410 1248 1385 1165 1120 793 562 80 836 Complex 2 75 4000 3500 3000 2500 2000 1500 1000 500 Wavenumber / cm -1 Figure S14. Infrared spectrum of compound 3. 100 Transmittance / % 95 90 3433 1469 1543 1618 1408 1598 1376 1076 793 562 840 Complex 3 85 4000 3500 3000 2500 2000 1500 1000 500 Wavenumber / cm -1 S15