126.7, 126.4, 125.7, 123.4, 122.0, 114.4, 13.1, 2.9,
2.8 ppm.
The same method was used to synthesize
HC(SiMe 2 OPh) 3 , which has been reported pre-
viously using a different synthetic method ( 45 ).
TheidentityofHC(SiMe 2 OPh) 3 was confirmed
by^1 HNMRspectroscopy.
Synthesis of (CH 3 OCH 2 CH 2 OCH 3 ) 2
KC(SiMe 2 OPh) 3
Solid MeK (0.11 g, 1.9 mmol) was slowly added
to a stirring solution of 1 (0.91 g, 1.9 mmol) dis-
solved in Et 2 O (10 ml) and dimethoxyethane
(3 ml); bubbles evolved during the course of
addition. The reaction mixture was then allowed
to stir for 3 hours, during which time a white
microcrystalline solid precipitated from solu-
tion. The solid was collected by filtration and
dried under vacuum (0.65 g, 0.95 mmol, 49%).
Anal. calcd. for KC 33 H 53 O 7 Si 3 : C, 57.85; H, 7.80.
Found: C, 57.83; H, 7.60.^1 H NMR (500 MHz,
THF-d8):d7.15(6H,t),6.91(6H,d),6.83(3H,t),
3.42 (8 H, s), 3.26 (12 H, s), 0.24 (18 H, s) ppm.^13 C
NMR (500 MHz, THF-d8):d158.3, 129.7, 122.2,
121.0, 72.7, 58.9, 16.8, 15.7, 5.2 ppm.
Synthesis of KC(SiMe 2 OC 10 H 7 ) 3
HC(SiMe 2 OC 10 H 7 ) 3 (0.967 g, 1.57 mmol) was dis-
solved in THF (15 ml). Freshly prepared MeK
(0.0850 g, 1.57 mmol) was added as a solid to
the stirring reaction mixture; bubbles evolved
from the mixture over the course of an hour.
After 3 hours, the reaction mixture was filtered
through diatomaceous earth and solvent was re-
moved under reduced pressure, leaving a sticky
colorless residue. Hexane was added to precip-
itate a white solid, KC(SiMe 2 OC 10 H 7 ) 3 (1.20 g,
76%), which was collected by filtration. Anal.
calcd. for KC 37 H 39 O 3 Si 3 :C,67.84;H,6.00.Found:
C, 67.59; H, 6.31.^1 H NMR (500 MHz, THF-d8):d
8.42 (3 H, d), 7.71 (3 H, d), 7.49 (3 H, d), 7.28 (12 H,
m), 0.38 (18 H, s) ppm.^13 C NMR (500 MHz, THF-
d8):d154.8, 135.9, 129.7, 127.7, 126.9, 125.6, 124.4,
124.2, 118.7, 114.5, 16.2, 5.9, 5.8 ppm.
Synthesis of Co(C(SiMe 2 OPh) 3 ) 2
Solid CoCl 2 (18.2 mg, 0.140 mmol) was
addedtoastirringTHFsolution(10ml)of
(CH 3 OCH 2 CH 2 OCH 3 ) 2 KC(SiMe 2 OPh) 3 (200. mg,
0.290 mmol) at room temperature, and then
the mixture was stirred for 2 hours at 60°C. The
solvent was removed in vacuo, and the resulting
blue-green solid was dissolved in hexanes. The
hexanes solution was stirred at 60°C for 1 hour
to form a yellow-green solution. The hexanes
solution was filtered through diatomaceous earth
and was concentrated in vacuo. Red-brown crys-
tals of Co(C(SiMe 2 OPh) 3 ) 2 (0.044 g, 39%) suitable
for x-ray diffraction grew in 2 hours at−30°C.
Anal. calcd. for CoC 50 H 66 Si 6 O 6 :C,60.63;H,6.72.
Found: C, 60.98; H, 6.84.
Synthesis of Co(C(SiMe 2 OC 10 H 7 ) 3 ) 2 (1)
Solid CoBr 2 (41.6 mg, 0.190 mmol) was added to
a stirring THF (8 ml) solution of KC(SiMe 2 OC 10 H 7 ) 3
(249 mg, 0.380 mmol) at room temperature. The
reaction mixture was stirred for 4 hours at 60°C,
after which time the solution had turned green.
The reaction mixture was filtered through dia-
tomaceous earth, and solvent was removed
under reduced pressure, leaving a green solid.
The green solid was dissolved in hexanes (20 ml)
andfilteredtogiveanemeraldgreensolution,
from which brown-red crystals of 1 (17.8 mg, 7%)
suitable for x-ray diffraction grew over the course
of 3 days. Compound 1 is insoluble in all common
organic solvents except THF, in which it forms a
green solution. Anal. calcd. for CoC 74 H 78 O 6 Si 6 :
C, 68.85; H, 6.09. Found: C, 68.36; H, 6.03.
Cooling the green hexanes solution ap-
pears to favor precipitation of the THF solvate,
Co(C(SiMe 2 OC 10 H 7 ) 3 ) 2 (THF). Green crystals not
suitable for single-crystal x-ray diffraction were
grown from the green hexanes solution over
1 day at−30°C, collected by filtration, and
thoroughly dried in vacuo. Anal. calcd. for
CoC 78 H 86 O 7 Si 6 : C, 68.74; H, 6.36. Found: C,
68.66; H, 6.52.Synthesis of Zn(C(SiMe 2 OC 10 H 7 ) 3 ) 2 (2)
At room temperature, a solution of ZnBr 2 (35.1 mg,
0.155 mmol) dissolved in THF (2 ml) was added
to a solution of KC(SiMe 2 OC 10 H 7 ) 3 (206 mg,0.314 mmol) dissolved in THF (8 ml), and the
mixture was stirred at room temperature for
12 hours. The reaction mixture was subsequently
filtered through diatomaceous earth, and the
THF solvent was removed under reduced pres-
sure, leaving a white solid. The colorless solid
was stirred in hexanes (20 ml) and filtered to
give a pale-yellow solution, from which color-
less crystals of 1 (36.7 mg, 9%) suitable for x-ray
diffraction grew over the course of 1 day. Anal.
calcd. for ZnC 74 H 78 O 6 Si 6 : C, 68.51; H, 6.06. Found:
C, 68.14; H, 5.92.Synthesis of Co0.02Zn0.98
(C(SiMe 2 OC 10 H 7 ) 3 ) 2 (3)
Initially, CoBr 2 (THF) was prepared by dissolving
CoBr 2 (6.2 mg, 0.028 mmol) in THF (5 ml) and
then removing the solvent under reduced pres-
sure. A suspension of CoBr 2 (THF) (0.028 mmol)
and ZnBr 2 (57.4 mg, 25.5 mmol) was prepared in
Et 2 O (4 ml), and this suspension was added to a
stirring solution of KC(SiMe 2 OC 10 H 7 ) 3 (371 mg,
0.567 mmol) dissolved in Et 2 O(6ml).The
mixturewasstirredfor1houratroomtem-
perature and then filtered through diatomaceous
earth. A light pink powder was collected from theBuntinget al.,Science 362 , eaat7319 (2018) 21 December 2018 6of9
700
600
500
400
300
200
100
0
0.0 0.1 0.2 0.3 0.4 0.5ABCMagnetization (μB)Magnetization (μB)Dτ (s) τ (s)10110010 −^110 −^210 −^310 −^410 −^5
0.00 0.05 0.10 0.15 0.20 0.25 0.30
T−^1 (K−^1 )
3210−1−2−3
−1.0 −0.5 0.0 0.5 1.03210−1−2−3
−1.0 −0.5 0.0 0.5 1.0Field (T)1 , 0 Oe
1 , 3000 Oe
3 , 3000 Oe32 Oe/s
1.8 K
3 K
4 K
5 K32 Oe/s
1.8 K
3 K
4 K
5 K1.8 K
1
3Field (T) Field (T)Fig. 5. Magnetic relaxation dynamics.(A) Arrhenius plot showing the natural log of relaxation time,
t, versus inverse temperature for 1 in the absence of an applied dc field (black circles), 1 under a
3000-Oe dc field (red circles), and 3 in the absence of an applied dc field (blue circles). Relaxation
times are determined from fits of ac susceptibility measurements over the temperature range of 4 to
70 K. The purple and green lines represent fits of the relaxation data for 1 under 0 and 3000 Oe,
respectively. (B) dc relaxation and magnetization times for 1 (green circles) and 3 (purple circles).
The solid lines are from fits describing relaxation via tunneling and direct relaxation processes as
described in the text and methods. (C) Variable-field magnetization data for 1 collected at temperatures
ranging from 1.8 to 5 K at a field sweep rate of 32 Oe/s. (D) Variable-field magnetization data for
3 collected at temperatures ranging from 1.8 to 5 K at a field sweep rate of 32 Oe/s.RESEARCH | RESEARCH ARTICLE
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