Heteroleptic manganese compounds as potential precursors for manganese based thin films and nanomaterials

Article abstract of DOI:10.1039/d0ra05225f

Heteroleptic manganese compounds, [Mn(tmhd)(TMEDA)Cl]2 (1), [Mn(tmhd)(dmamp)]2 (2), Mn2(tmhd)2(edpa)2(μ-THF) (3), [Mn(dmampea)(NEt2)]2 (4), and Mn(dmampea)(iPr-MeAMD) (5), were synthesized and characterized. Compound 5 was a volatile liquid. Structural analysis revealed that 1-4 were dimers. Compounds 1 and 3, 2, and 4 had distorted octahedral, distorted trigonal-bipyramidal, and distorted tetrahedral geometries around the Mn centers, respectively. Based on thermogravimetric analysis, the residues of 2 and 3 were expected to be MnO and Mn3O4, respectively. According to thermogravimetric analysis, 4 showed a higher residual value, whereas 5 exhibited a lower value than those expected for manganese nitrides. This journal is

Full text of DOI:10.1039/d0ra05225f

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Heteroleptic manganese compounds as potential
precursors for manganese based thin films and
Cite this: RSC Adv., 2020, 10, 29659
nanomaterials†
ab
Sunju Lee,a Ga Yeon Lee,a Chang Gyoun Kim,ab Taek-Mo Chung
*
ab
*
and Bo Keun Park
Heteroleptic manganese compounds, [Mn(tmhd)(TMEDA)Cl]2 (1), [Mn(tmhd)(dmamp)]2 (2),
Mn2(tmhd)2(edpa)2(m-THF) (3), [Mn(dmampea)(NEt2)]2 (4), and Mn(dmampea)(iPr-MeAMD) (5), were
synthesized and characterized. Compound 5 was a volatile liquid. Structural analysis revealed that 1–4
were dimers. Compounds 1 and 3, 2, and 4 had distorted octahedral, distorted trigonal-bipyramidal, and
distorted tetrahedral geometries around the Mn centers, respectively. Based on thermogravimetric
analysis, the residues of 2 and 3 were expected to be MnO and Mn3O4, respectively. According to
thermogravimetric analysis, 4 showed a higher residual value, whereas 5 exhibited a lower value than
those expected for manganese nitrides.
Received 14th June 2020
Accepted 3rd August 2020
DOI: 10.1039/d0ra05225f
rsc.li/rsc-advances
Manganese-containing thin lms have been deposited by
CVD and ALD from Mn(tmhd)3,2a,3,11a,c,d,e,12c MnCp2,11f
Mn(EtCp)2,11f,j,12a Mn(CpR)(CO)3,11f,h,l Mn(hfa)2$TMEDA,11i,n
Introduction
Manganese is an important component in several classes of
materials, such as solid electrolytes in batteries1 and solid oxide
fuel cells2 as well as magnetoresistive oxides,3 magnetic mate-
rials,4 supercapacitors,5 catalysts,6 and microelectronics.7
Manganese-based thin lms have been deposited via several
methods, including liquid-phase electrochemical methods,8
physical vapor deposition (PVD),4f,5b,c,9 molecular beam epitaxy
(MBE),4a,b,d,10 chemical vapor deposition (CVD),2a,3,11 and atomic
layer deposition (ALD).7c,12 The CVD and ALD processes are
useful to form large-area thin lms of good uniformity using
metal precursors. Furthermore, through ALD techniques,
highly uniform thin lms can be formed on very high aspect
ratio structures. The success of the CVD and ALD processes
critically depends on the availability of volatile and thermally
stable precursors. The ideal precursors must have high vapor
pressure, high volatility, high purity, low deposition tempera-
ture, high deposition rate, chemical and thermal stability
during transportation, low cost, and a simple reaction path to
deposition. Moreover, they must allow high control over
composition, easy handling, easy treatment, and easy removal
of byproducts.
Mn(NtBu2)2,11k
bis(2,2,6,6-tetramethylpiperidido)man-
ganese(II),11m Mn(N,N0-di-isopropylpentylamidinato)2,11g,h and
Mn(OCRR0CNtBu)2.12b However, new manganese precursors
must be developed because of the thermal instability, low shelf
life, and low vapor pressures of the existing precursors.
Our group has studied the applications of CVD and ALD and
the syntheses of metal precursors that contain an aminoalkoxide
group, in which the two alkyl groups positioned on the a-carbon
of the hydroxyl group are substituted, and exhibit improved
volatility13 as well as N-alkoxy carboxamides having adjusted both
sides of the amide group.14 Recently, we investigated the
syntheses and applications of heteroleptic precursors with two
distinct ligands attached to the metal center. A heteroleptic
precursor may lead to improved volatility, stability, and reactivity
compared to homoleptic precursors that contain the same
ligands. Also, we are studying a precursor that contains an ami-
noamide ligand that was formed by substituting the hydroxyl
group of the aminoalkoxide moiety with an amide group.
In this paper, we report the synthesis of [Mn(tmhd)(TMEDA)
Cl]2 (1) (tmhd ¼ 2,2,6,6-tetramethyl-3,5-heptanedionate, TMEDA
¼ N,N,N0,N0-tetramethylethylenediamine), [Mn(tmhd)(dmamp)]2
(2) (dmamp ¼ 1-dimethylamino-2-methyl-2-propoxide), Mn2(-
aThin Film Materials Research Center, Korea Research Institute of Chemical
Technology (KRICT), 141 Gajeong-Ro, Yuseong-Gu, Daejeon 34114, Republic of
Korea. E-mail: tmchung@krict.re.kr; parkbk@krict.re.kr
tmhd)2(edpa)2(m-THF) (3) (edpa
propanamide), [Mn(dmampea)(NEt2)]2 (dmampea
(dimethylamino)-2-methylpropan-2-yl)(ethyl)amide) (4), and
Mn(dmampea)(iPr-MeAMD) (iPr-MeAMD ¼ N,N0-diisopropylace-
tamidinate) (5) as heteroleptic precursors for the preparation of
thin lms containing manganese. These compounds were
¼
N-ethoxy-2,2-dimethyl-
(1-
¼
bDepartment of Chemical Convergence Materials, University of Science and Technology
(UST), 217, Gajeong-Ro, Yuseong-Gu, Deajeon 34113, Republic of Korea
† Electronic supplementary information (ESI) available: Molecular structure of
molecules
1 and 2 in the asymmetric unit of 4 (Fig. S1). CCDC
2002601–2002604. For ESI and crystallographic data in CIF or other electronic
format see DOI: 10.1039/d0ra05225f
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characterized via infrared (IR) spectroscopy and microanalysis as
well as single-crystal X-ray diffraction analysis.
Lithium aluminum hydride 15.0 g (0.06 mol) was suspended
in THF (100 mL) under ice-water cooling, the mixture was stir-
red for 1 h, and N-(1-(dimethylamino)-2-methylpropan-2-yl)
acetamide (3.23 g, 0.02 mol) in THF was slowly added. The
mixture was stirred for 12 h under reux, the temperature was
reduced to room temperature, and water (3 mL) and a 10%
aqueous sodium hydroxide solution (15 mL) were added drop-
wise to the reaction mixture under ice-water cooling. Aer the
removal of the insoluble fraction via ltration, the ltrate was
dried over anhydrous MgSO4, and the solvent was removed via
distillation under reduced pressure to afford N2-ethyl-N1,N1,2-
trimethylpropane-1,2-diamine. Yield: 2.23 g (98%). 1H NMR
(CDCl3, 400 MHz): d 1.02 (s, 6H, –C(CH3)2), 1.09 (t, J ¼ 7.12 Hz,
3H, –CH2CH3), 2.22 (s, 2H, –NCH2–), 2.31 (s, 6H, –N(CH3)2), 2.54
(q, J ¼ 7.16 Hz 2H, –NHCH2–).
Experimental
General comments
All reactions were carried out under inert dry conditions using
standard Schlenk line techniques or in an argon-lled glove
box. Tetrahydrofuran (THF), hexane, and toluene solvents were
puried using the Innovative Technology PS-MD-4 solvent-
purication system. Moreover, Na(dmamp),13b edpaH,14a and
Li(iPr-MeAMD)15 were synthesized via the referenced modied
methods. All other chemicals were purchased from Aldrich. IR
spectra were obtained using a Nicolet Nexus Fourier-transform
IR (FT-IR) spectrophotometer. Elemental analysis was con-
ducted using the Thermo Scientic Flash 2000 Organic
Elemental Analyzer. Thermogravimetric analysis (TGA) was
performed using a Setaram TG/DTA 92-18 instrument.
n
Furthermore, BuLi (2.7 mL) was added dropwise to a solu-
tion of N2-ethyl-N1,N1,2-trimethylpropane-1,2-diamine (1.0 g,
7.0 mmol) in THF (50 mL) at 0 ꢁC and the reaction mixture was
stirred for 12 h. The solvent of the mixture was removed in vacuo
to obtain lithium (1-(dimethylamino)-2-methylpropan-2-yl)
Synthesis of Na(edpa)
(ethyl)amide (Li(dmampea)) as
a
yellow powder. This
First, edpaH (1.0 g, 6.7 mmol) was added dropwise to a NaH
(0.16 g, 6.9 mmol) suspension in toluene (100 mL). Aer
reacting for 12 h, the mixture was ltered. A white powder was
obtained via evaporation of the ltrate in vacuo. Yield: 0.95 g
(84%). 1H NMR (C6D6, 400 MHz): d 1.26 (t, J ¼ 8.00 Hz, 3H,
–OCH2CH3), 1.30 (S, 9H, –C(CH3)3), 3.22 (q, J ¼ 8.00, 2H,
–OCH2CH3).
compound was used without further purication.
Synthesis of [Mn(tmhd)(TMEDA)Cl]2 (1)
Na(tmhd) (0.82 g, 4.0 mmol) was added to a solution of MnCl2
(0.50 g, 4.0 mmol) and TMEDA (0.46 g, 4.0 mmol) in THF (30 mL).
Aer stirring the mixture for 12 h, the solvent was removed in
vacuo. The residues were extracted with hexane and ltered. The
crude product was obtained via evaporation of the ltrate in vacuo,
and it was puried via recrystallization from toluene at room
temperature to afford a pure product as yellow crystals. Yield:
1.04 g (67%). FT-IR (KBr, cmꢂ1): 3005 (m), 2961 (s), 2867 (m), 2836
(s), 2796 (m), 1591 (s), 1574 (s), 1535 (s), 1501 (s), 1456 (s), 1415 (s),
1399 (s), 1358 (s), 1287 (m), 1245 (m), 1223 (m), 1182 (w), 1164 (w),
1135 (m), 1065 (w), 1031 (m), 1018 (w), 954 (m), 931 (w), 867 (m),
793 (m), 772 (w), 736 (w), 606 (w), 583 (w), 474 (w), 436 (w);
elemental analysis calcd (%) for Mn2C34H70Cl2N4O4: C, 52.37; H,
9.05; N, 7.19; found: C, 55.24; H, 9.90; N, 8.72.
Synthesis of Li(dmampea)
Isobutylene oxide (35 mL, 0.39 mol) was added dropwise to
dimethylamine (50 mL of 40 wt% solution in H2O, 0.39 mol)
under ice-water cooling, and the reaction mixture was stirred at
ambient temperature for 12 h. Diethyl ether (200 mL) and water
(200 mL) were added to the solution. The organic layer was
separated, and the aqueous layer was extracted with diethyl
ether (2 ꢀ 200 mL). The combined organic layer was dried over
ꢁ
MgSO4 and ltered. Purication via distillation (110 C) affor-
ded 1-(dimethylamino)-2-methylpropan-2-ol as a colorless oil.
Yield: 40 g (89%). 1H NMR (CDCl3, 400 MHz): d 1.16 (s, 6H,
–C(CH3)2), 2.27 (s, 2H, –CH2–), 2.36 (s, 6H, –N(CH3)2).
Synthesis of [Mn(tmhd)(dmamp)]2 (2)
Concentrated sulfuric acid (60 mL) was slowly added to Na(tmhd) (0.82 g, 4.0 mmol) was added to a suspension of
stirred acetonitrile (200 mL) at 0 ꢁC. The resulting solution was MnCl2 (0.5 g, 4.0 mmol) in THF (30 mL). Aer stirring the
added dropwise to
a
mixture of 1-(dimethylamino)-2- mixture at room temperature for 6 h, Na(dmamp) (0.55 g, 4.0
methylpropan-2-ol (5 g, 42.69 mmol) in acetonitrile (200 mL) mmol) was added and the reaction mixture was stirred for 12 h.
ꢁ
at 0 C. The reaction mixture was stirred at room temperature The solvent of the mixture was removed in vacuo. The residues
for 2 days, and then crushed ice was poured onto the mixture. were extracted with hexane and ltered. The crude product was
The reaction mixture was subjected to reduced pressure to obtained via evaporation of the ltrate in vacuo, and it was
evaporate acetonitrile, cooled in an ice bath, and basied with puried via recrystallization from THF at room temperature to
an aqueous sodium hydroxide solution to adjust the pH to 10. afford a pure product as yellow crystals. Yield: 0.99 g (70%). FT-
The mixture was extracted three times with diethyl ether. The IR (KBr, cmꢂ1): 2962 (s), 2864 (m), 2836 (w), 2791 (w), 1588 (s),
combined organic layer was washed with water, dried over 1574 (s), 1549 (m), 1537 (m), 1505 (m), 1452 (w), 1406 (s), 1358
MgSO4, and concentrated to afford N-(1-(dimethylamino)-2- (m), 1246 (w), 1225 (w), 1190 (w), 1162 (w), 1136 (w), 1123 (w),
methylpropan-2-yl) acetamide as a light-yellow oil. Yield: 1034 (w), 1021 (w), 983 (m), 941 (m), 911 (w), 869 (w), 843 (w),
3.23 g (45%). 1H NMR (CDCl3, 400 MHz): d 1.33 (s, 6H, 790 (w), 760 (w), 738 (w), 609 (w), 582 (w), 539 (w), 474 (w), 450
–C(CH3)2), 1.93 (s, 3H, –CCH3), 2.32 (s, 6H, –N(CH3)2), 2.41 (s, (w); elemental analysis calcd (%) for Mn2C34H66N2O6: C, 57.62;
2H, –CH2–).
H, 9.39; N, 3.95; found: C, 57.14; H, 9.55; N, 3.87.
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2 and 3 were grown from a saturated THF solution at room
temperature. Crystals of 4 were isolated via recrystallization
from hexane. A specimen of suitable size and quality was coated
with Paratone oil and mounted onto a glass capillary. Reection
data were collected using a Bruker Apex II-CCD area-detector
diffractometer with graphite-monochromated MoKa radiation
Synthesis of Mn2(tmhd)2(edpa)2(m-THF) (3)
Na(tmhd) (0.82 g, 4.0 mmol) was added to a suspension of
MnCl2 (0.5 g, 4.0 mmol) in THF (30 mL). Aer stirring the
mixture at room temperature for 6 h, Na(edpa) (0.67 g, 4.0
mmol) was added and the reaction mixture was stirred for 12 h.
The solvent of the mixture was removed in vacuo. The residues
were extracted with hexane and ltered. The crude product was
obtained aer evaporation of the ltrate in vacuo, and it was
puried via recrystallization from THF at room temperature to
obtain a pure product as yellow crystals. Yield: 1.17 g (70%). FT-
IR (KBr, cmꢂ1): 2964 (s), 2869 (s), 1589 (s), 1572 (s), 1554 (s),
1539 (s), 1504 (s), 1479 (m), 1459 (w), 1389 (s), 1358 (m), 1324
(w), 1246 (w), 1224 (w), 1187 (m), 1136 (w), 1092 (w), 1055 (s), 956
(w), 935 (w), 899 (m), 868 (s), 792 (w), 762 (w), 737 (w), 612 (w),
537 (w), 525 (w), 492 (w), 474 (w); elemental analysis calcd (%)
for C40H74Mn2N2O9$H2O: C, 56.20; H, 8.96; N, 3.28; found: C,
56.59; H, 8.75; N, 3.67.
˚
(l ¼ 0.71073 A). The hemisphere of reection data were
collected as u scan frames with 0.3ꢁ per frame and an exposure
time of 10 s per frame. Cell parameters were determined using
the SMART program16 and rened with SAINT soware.17 Data
reduction was performed using SAINT soware.17 The data were
corrected for the Lorentz and polarization effects. Absorption
correction was applied using the SADABS program.18 The
structures were solved via direct methods and all nonhydrogen
atoms were subjected to anisotropic renement via full-matrix
least-squares on F2 using the SHELXTL/PC package.19
Hydrogen atoms were placed at their geometrically calculated
positions and rened on the corresponding carbon atoms using
the riding model with isotropic thermal parameters. CCDC
2002604 (1), CCDC 2002602 (2), CCDC 2002603 (3), and CCDC
2002601 (4) contain supplementary crystallographic data.†
Synthesis of [Mn(dmampea)(NEt2)]2 (4)
Li(dmampea) (0.60 g, 4.0 mmol) was added to a suspension of
MnCl2 (0.5 g, 4.0 mmol) in THF (30 mL). Aer stirring the
mixture at room temperature for 6 h, Li(NEt2) (0.31 g, 4.0 mmol)
was added, and the reaction mixture was stirred for 12 h. The
solvent of the reaction mixture was removed in vacuo. The
residues were extracted with hexane and ltered. The crude
product was obtained via evaporation of the ltrate in vacuo,
and it was puried via recrystallization from toluene at room
temperature to afford a pure product as brown crystals. Yield:
0.75 g (69%). FT-IR (KBr, cmꢂ1): 2962 (s), 2926 (s), 2861 (s), 2598
(w), 1648 (w), 1497 (s), 1377 (m), 1359 (m), 1330 (m), 1313 (m),
1261 (m), 1206 (m), 1173 (m), 1121 (w), 1044 (w), 1015 (w), 941
(w), 877 (w), 840 (w), 807 (w), 624 (w), 574 (w); elemental analysis
calcd (%) for C24H58Mn2N6$2H2O: C, 49.99; H, 10.84; N, 14.57;
found: C, 49.57; H, 10.16; N, 14.81.
Thermal analysis
TGA and differential thermal analysis (DTA) for the newly
synthesized compounds were performed using the Setaram TG/
Synthesis of Mn(dmampea)(iPr-MeAMD) (5)
Li(dmampea) (0.60 g, 4.0 mmol) was added to a suspension of
MnCl2 (0.5 g, 4.0 mmol) in THF (30 mL). Aer stirring the
mixture at room temperature for 6 h, Li(iPr-MeAMD) (0.59 g, 4.0
mmol) was added and the reaction mixture was stirred for 12 h.
The solvent of the reaction mixture was removed in vacuo. The
residues were extracted with hexane and ltered. The crude
product was obtained via evaporation of the ltrate in vacuo,
and it was puried via distillation at 110 ꢁC under a reduced
pressure of 10ꢂ1 Torr to obtain a pure product as a yellow liquid.
Yield: 0.54 g (40%). FT-IR (KBr, cmꢂ1): 2961 (s), 2927 (s), 2862
(s), 2787 (w), 2600 (w), 1650 (w), 1496 (s), 1376 (s), 1357 (s), 1314
(s), 1261 (w), 1204 (m), 1173 (m), 1150 (m), 1121 (m), 1083 (w),
1050 (m), 1014 (w), 939 (w), 876 (w), 804 (w), 731 (w); elemental
analysis calcd (%) for C16H37MnN4: C, 56.45; H, 10.96; N, 16.46;
found: C, 56.40; H, 10.57; N, 16.29.
X-ray crystallography
Crystals of 1 suitable for X-ray analysis were obtained via
recrystallization from toluene at room temperature. Crystals of Scheme 1 Synthesis of compounds 1–5.
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DTA 92-18 instrument. The TG data of the compounds were The crystallographic data are summarized in Table 1. Selected
ꢂ1
ꢁ
ꢁ
obtained up to 800 C at a heating rate of 10 C min under bond lengths and angles of 1–3 are listed in Table 2.
atmospheric pressure with N2 as a carrier gas. TG sampling was The crystals of 1–3 formed dimeric structures through the
carried out inside an argon-lled glove box to avoid air contact. two Cl atoms (for 1), two O atoms of the two dmamp ligands (for
However, the samples were exposed to air for less than 1 min 2), and two O atoms of the two edpa ligands and one O atom of
when setting them in the TGA apparatus.
THF (for 3). The crystal structures of 1 and 3 had a distorted
octahedral geometry around each central Mn atom, unlike 2
which had a distorted trigonal-bipyramidal geometry (Fig. 1–3).
Compound 3 was expected to be a 5-coordinated molecule like
2; however, it had a distorted octahedral geometry with 6-
coordination, which contained the O atom of the THF molecule
bridged to the two Mn atoms. A possible reason for this
behavior is that the edpa ligand was sterically smaller than the
dmamp ligand because the backbone of edpa was planar due to
the double bond character.
In 1–3, the tmhd ligands were bonded to the Mn atoms that
formed six-membered metallacycles: Mn1–O1–C1–C2–C3–O2
with an O1–Mn1–O2 bite angle of 83.48(3)ꢁ for 1, Mn1–O1–C1–
C2–C3–O2 with an O1–Mn1–O2 bite angle of 84.80(6)ꢁ for 2, and
Mn1–O3–C8–C9–C10–O4 and Mn11–O13–C28–C29–C30–O14
with O3–Mn1–O4 and O13–Mn11–O14 bite angles of 86.47(15)ꢁ
and 86.21(3)ꢁ, respectively, for 3. The lengths of the Mn1–O1
Results and discussion
The reaction of MnCl2 with 1 equiv. of Na(tmhd) in the presence
of 1 equiv. TMEDA afforded manganese(II) compound 1 in 67%
yield (Scheme 1). Aer mixing MnCl2 with 1 equiv. of Na(tmhd)
in THF for 6 h, the mixture was treated with 1 equiv. of Na(d-
mamp) and Na(edpa), and it afforded 2 (76%) and 3 (69%),
respectively (Scheme 1).
Aer the reaction of MnCl2 with 1 equiv. of Li(dmampea),
which is an aminoamide ligand, for 6 h in THF and treatment of
the mixture with 1 equiv. of Li(NEt2) and Li(iPr-MeAMD), we
obtained 4 (69%), and 5 (40%), respectively. Compound 5 was
liquid and vaporized well when distilled at 110 ꢁC under
a reduced pressure of 10ꢂ1 Torr.
The compounds had good solubility in organic solvents,
such as toluene, hexane, and diethyl ether under inert
conditions.
The crystals of 1–3 were obtained from saturated solutions of
toluene (for 1) and THF (for 2 and 3) at room temperature. The
crystal of 2 exhibited thermal disorder with the tmhd ligand.
˚
and Mn1–O2 bonds (tmhd) were 2.1109(8) and 2.1141(8) A in 1,
˚
and 2.0868(15) and 2.0959(16) A in 2, respectively. In 3, the
lengths of the Mn1–O3, Mn1–O4, Mn11–O13, and Mn11–O14
˚
bonds were 2.074(4), 2.092(4), 2.076(4), and 2.084(4) A, respec-
tively. The bond lengths and angles tended to move oppositely;
i.e., 1 had the longest bonds and smallest bond angles.
Table 1 Crystallographic data and data collection parameters for 1–4
1
2
3
4
Formula weight
Crystal system
Space group
779.72
Monoclinic
P21/c
710.78
Monoclinic
P21/n
838.91
Monoclinic
P21/c
540.64
Triclinic
ꢀ
P1
Temperature (K)
100(1)
100(1)
100(1)
100(1)
0.71073
˚
Wavelength (A)
0.71073
10.3578(3)
18.3221(5)
11.8508(3)
90
111.7850(10)
90
2088.39(10)
2
1.240
0.770
836
0.20 ꢀ 0.18 ꢀ 0.09
2.12–28.40
ꢂ13 # h # 12
0 # k # 24
0 # l # 15
5228
0.71073
10.1761(4)
9.1185(4)
21.7996(9)
90
93.970(2)
90
2017.95(15)
2
1.170
0.665
768
0.20 ꢀ 0.12 ꢀ 0.08
1.87–28.31
ꢂ13 # h # 13
0 # k # 12
0 # l # 28
4994
0.71073
12.7642(5)
21.0617(9)
17.1722(8)
90
90.417(2)
90
4616.4(3)
4
1.207
0.596
1808
0.20 ꢀ 0.12 ꢀ 0.04
1.53–28.27
ꢂ16 # h # 16
0 # k # 28
0 # l # 22
11 322
˚
a (A)
9.6293(3)
11.7366(4)
13.3435(4)
95.882(2)
92.369(2)
91.115(2)
1498.37(8)
2
1.198
0.864
588
0.70 ꢀ 0.34 ꢀ 0.26
1.54–26.00
ꢂ11 # h # 11
ꢂ14 # k # 14
0 # l # 16
5882
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
g (ꢁ)
3
˚
Volume (A )
Z
Pcalcd (Mg mꢂ3
)
m (mmꢂ1
F (000)
)
Crystal size (mm3)
Theta range (ꢁ)
Index ranges
Indep. re.
GOF on F2
1.080
0.0253
0.0635
1.052
0.0479
0.1483
1.091
0.0951
0.2593
1.063
0.0492
0.1286
R1 [I > 2s(I)]a
wR2 (all data)b
a
2
R1 ¼ (SkFo| ꢂ |Fck)/S|Fo|. b wR2 ¼ [Su(Fo ꢂ Fc2)2/Su(Fo2)2]1/2
.
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Compounds 1–3 contained four-membered rings that were those of the Mn–Cl bridging compounds.20 Compounds 2 and 3
formed by the atoms bridged between the two Mn atoms (Cl for formed four-membered rings with the O atoms of the two
1, O for 2 and 3). For 1, the four-membered ring Mn1–Cl1– dmamp and edpa ligands, respectively. The bond angles of the
Mn1i–Cl1i had bond angles of 94.127(10)ꢁ (Mn1–Cl1–Mn1i) and Mn1–O3–Mn1i–O3i ring in 2 were 84.85(6)ꢁ (O3–Mn1–O3i) and
i
85.872(10)ꢁ (Cl1–Mn1–Cl1 ) and bond lengths of 2.5343(3) A 95.15(6)ꢁ (Mn1–O3–Mn1i), whereas those of the Mn1–O2–
˚
i
(Mn1–Cl1) and 2.5310(3) A (Mn1–Cl1 ), which were in similar to Mn11–O12 ring in 3 were 81.61(14)ꢁ (O2–Mn1–O12), 81.31(14)ꢁ
˚
Table 2 Selected bond lengths (A˚) and bond angles (ꢁ) for 1–3
˚
Bond lengths (A)
1
2
3
Mn(1)–O(1)
Mn(1)–O(2)
Mn(1)–N(1)
Mn(1)–N(2)
Mn(1)–Cl(1)
Mn(1)–Cl(1)i
2.1109(8)
2.1141(8)
2.3443(10)
2.3866(11)
2.5343(3)
2.5310(3)
Mn(1)–O(1)
Mn(1)–O(2)
Mn(1)–O(3)
Mn(1)–O(3)i
Mn(1)–N(1)
2.0868(15)
2.0959(16)
2.0592(17)
2.1097(14)
2.3106(18)
Mn(1)–O(1)
Mn(1)–O(2)
Mn(1)–O(3)
Mn(1)–O(4)
2.229(4)
2.146(4)
2.074(4)
2.092(4)
2.578(4)
2.149(4)
2.203(4)
2.162(4)
2.076(4)
2.084(4)
2.147(4)
2.455(4)
3.112(1)
Mn(1)–O(5)
Mn(1)–O(12)
Mn(11)–O(11)
Mn(11)–O(12)
Mn(11)–O(13)
Mn(11)–O(14)
Mn(11)–O(2)
Mn(11)–O(5)
Mn(1)/Mn(11)
Mn(1)/Mn(1)i
Bond angles (ꢁ)
1
3.7084(3)
Mn(1)/Mn(1)i
3.0774(6)
2
3
O(1)–Mn(1)–O(2)
O(1)–Mn(1)–N(1)
O(1)–Mn(1)–N(2)
O(2)–Mn(1)–N(2)
O(2)–Mn(1)–N(1)
N(1)–Mn(1)–N(2)
O(1)–Mn(1)–Cl(1)
O(2)–Mn(1)–Cl(1)
N(1)–Mn(1)–Cl(1)
N(2)–Mn(1)–Cl(1)
O(1)–Mn(1)–Cl(1)i
O(2)–Mn(1)–Cl(1)i
N(1)–Mn(1)–Cl(1)i
N(2)–Mn(1)–Cl(1)i
Cl(1)–Mn(1)–Cl(1)i
Mn(1)–Cl(1)–Mn(1)i
83.48(3)
86.01(3)
91.03(4)
86.70(4)
161.21(4)
77.95(4)
178.11(3)
95.39(2)
95.48(3)
90.42(3)
92.91(3)
103.64(3)
92.38(3)
169.28(3)
85.872(10)
94.127(10)
O(1)–Mn(1)–O(2)
O(3)–Mn(1)–O(1)
O(3)–Mn(1)–O(2)
O(1)–Mn(1)–N(1)
O(2)–Mn(1)–N(1)
O(3)–Mn(1)–N(1)
O(1)–Mn(1)–O(3)i
O(2)–Mn(1)–O(3)i
O(3)–Mn(1)–O(3)i
O(3)i–Mn(1)–N(1)
Mn(1)–O(3)–Mn(1)i
84.80(6)
112.91(6)
109.92(7)
141.27(7)
85.72(7)
105.64(7)
101.30(6)
160.62(7)
84.85(6)
78.02(6)
95.15(6)
O(3)–Mn(1)–O(4)
O(3)–Mn(1)–O(2)
O(4)–Mn(1)–O(2)
O(3)–Mn(1)–O(12)
O(4)–Mn(1)–O(12)
O(2)–Mn(1)–O(12)
O(3)–Mn(1)–O(1)
O(4)–Mn(1)–O(1)
O(2)–Mn(1)–O(1)
O(12)–Mn(1)–O(1)
O(5)–Mn(1)–O(2)
O(5)–Mn(1)–O(12)
O(5)–Mn(1)–O(1)
O(5)–Mn(1)–O(3)
O(5)–Mn(1)–O(4)
O(13)–Mn(11)–O(14)
O(13)–Mn(11)–O(2)
O(14)–Mn(11)–O(2)
O(13)–Mn(11)–O(12)
O(14)–Mn(11)–O(12)
O(2)–Mn(11)–O(12)
O(13)–Mn(11)–O(11)
O(14)–Mn(11)–O(11)
O(2)–Mn(11)–O(11)
O(12)–Mn(11)–O(11)
O(13)–Mn(11)–O(5)
O(14)–Mn(11)–O(5)
O(2)–Mn(11)–O(5)
O(12)–Mn(11)–O(5)
O(11)–Mn(11)–O(5)
Mn(1)–O(2)–Mn(11)
Mn(1)–O(12)–Mn(11)
Mn(1)–O(5)–Mn(11)
86.47(15)
152.89(15)
111.30(15)
115.49(16)
102.40(15)
81.61(14)
86.26(15)
103.08(17)
70.23(14)
147.30(16)
74.29(13)
71.86(14)
84.48(15)
90.64(14)
171.70(14)
86.21(15)
117.10(15)
100.20(15)
151.25(15)
113.41(15)
81.31(14)
87.85(15)
93.81(17)
151.91(15)
70.77(14)
88.07(14)
171.57(15)
76.96(14)
74.23(14)
92.16(15)
92.93(15)
92.43(15)
76.35(11)
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Fig. 1 Molecular structure of 1. Ellipsoids are set at 50% probability. H
atoms omitted for clarity.
Fig. 3 Molecular structure of 3. Ellipsoids are set at 50% probability. H
atoms omitted for clarity.
(O2–Mn11–O12), 92.93(15)ꢁ (Mn1–O2–Mn11), and 92.43ꢁ (Mn1–
˚
The crystals of 4 were obtained from saturated hexane.
Compound 4 crystallized with two molecules in the asymmetric
unit. Each molecule exhibited slightly different bond lengths
and angles. Details of the crystallographic data are summarized
in Table 1. Selected bond lengths and angles of 4 are listed in
Table 3.
The crystal structure of 4 was dimeric with distorted tetra-
hedral geometry around each central Mn atom (Fig. 4). The
two N atoms of the NEt2 ligands were bridged between the two
Mn atoms, and the two dmampea ligands were combined to one
Mn atom in a chelating form (Fig. 4).
O12–Mn11). The Mn–O lengths were 2.0592(17) A (Mn1–O3)
i
˚
˚
and 2.1097(14) A (Mn1–O3 ) for 2, and 2.146(4) A (Mn1–O2),
˚
˚
˚
2.147(4) A (Mn11–O2), 2.149(4) A (Mn1–O12), and 2.162(4) A
(Mn11–O12) for 3. The bond lengths and angles for 2 and 3 were
similar to those of previously reported compounds.21 The four-
membered metallacycles of 1 and 2 were at because of the
inversion centers; however, those of 3 was a buttery form
because of the bonded THF. In 3, the bond angle of the O atom
of the bridged THF molecule with the two Mn atoms was
76.35(11)ꢁ (Mn1–O5–Mn11), and the coordinated bond lengths
˚
of Mn1–O5 and Mn11–O5 were 2.578(4) and 2.455(4) A,
The dmampea ligand and Mn atom formed the ve-
membered metallacycles Mn1–N1–C1–C2–N2 for molecule 1
and Mn2–N4–C4–C5–N5 for molecule 2. The bite angles of
molecules 1 and 2 were 82.51(10)ꢁ (N1–Mn1–N2) and 82.70(10)ꢁ
(N4–Mn2–N5), respectively. The lengths of the Mn–N coordi-
nation bonds of 4 were 2.250(3) (Mn1–N1) for molecule 1 and
respectively. The angle between the two planes (Mn1–O2–O12
and Mn11–O2–O12) of the buttery form was 34.63(9)ꢁ.
In 1–3, the TMEDA, dmamp, and edpa ligands that were bonded
to the Mn atoms afforded the ve-membered metallacycles Mn1–
N1–C12–C13–N2 (for 1), Mn1–O3i–C12–C13–N1 (for 2), and Mn1–
O1–N1–C1–O2 and Mn11–O11–N11–C21–O12 (for 3), with bite
angles of 77.95(4)ꢁ (N1–Mn–N2), 78.02(6)ꢁ (O3i–Mn1–N1), and
70.23(14)ꢁ (O1–Mn1–O2) and 70.77(14)ꢁ (O11–Mn11–O12), respec-
tively. The lengths of the coordinated bonds were 2.3443(10) (Mn1–
˚
2.260(3) A (Mn2–N4) for molecule 2. The Mn–N terminal bond
Table 3 Selected bond lengths (A˚) and bond angles (ꢁ) for 4
˚
˚
N1) and 2.3866(11) A (Mn1–N2) for 1, 2.3106(18) A (Mn1–N1) for 2,
˚
and 2.229(4) (Mn1–O1) and 2.203 A (Mn11–O11) for 3.
˚
Bond lengths (A)
The distance between the two Mn atoms, Mn/Mn (3.7084(3)
˚
˚
A) for 1 was longer than those for 2 and 3 (3.0774(6) A and
Molecule 1
Molecule 2
˚
3.112(1) A, respectively) because of the large size of bridging Cl.
Mn(1)–N(1)
Mn(1)–N(2)
Mn(1)–N(3)
Mn(1)–N(3)i
Mn(1)/Mn(1)i
2.250(3)
2.023(2)
2.143(2)
2.143(2)
2.8868(8)
Mn(2)–N(4)
Mn(2)–N(5)
Mn(2)–N(6)
Mn(2)–N(6)i
Mn(2)/Mn(2)i
2.260(3)
2.019(3)
2.142(2)
2.145(2)
2.9025(8)
Bond angles (ꢁ)
Molecule 1
Molecule 2
N(1)–Mn(1)–N(2)
N(1)–Mn(1)–N(3)
N(1)–Mn(1)–N(3)i
N(2)–Mn(1)–N(3)
N(2)–Mn(1)–N(3)i
N(3)–Mn(1)–N(3)i
Mn(1)–N(3)–Mn(1)i
82.51(10)
114.78(9)
112.09(9)
123.30(10)
129.20(10)
95.31(9)
N(4)–Mn(2)–N(5)
N(4)–Mn(2)–N(6)
N(4)–Mn(2)–N(6)i
N(5)–Mn(2)–N(6)
N(5)–Mn(2)–N(6)i
N(6)–Mn(2)–N(6)i
Mn(2)–N(6)–Mn(2)i
82.70(10)
113.25(10)
114.60(10)
126.88(10)
125.33(10)
94.78(8)
84.69(9)
85.22(8)
Fig. 2 Molecular structure of 2. Ellipsoids are set at 50% probability. H
atoms omitted for clarity.
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Fig. 4 Molecular structure of molecule 1 in the asymmetric unit of 4.
Ellipsoids are set at 50% probability. H atoms omitted for clarity.
Fig. 6 Thermal analyses of 4 and 5.
lengths of 4 were 2.023(2) (Mn1–N2) for molecule 1 and 2.019(3)
and 3. For 2, the rst and second weight losses were 8.1% and
26.7% at 100–130 ꢁC and 165–245 ꢁC, respectively. The third
part was 30.7% at 280–325 ꢁC. In the case of 3, the weight losses
were 4.3, 63.2, and 10.9% at 50–100, 105–245, and 255–288 ꢁC,
respectively. The nal residues of 2 and 3 were 20.9% and
17.7%, respectively. The calculated residues for the manganese
oxides obtained from 2 and 3 are 20.0 and 17.0, 22.3 and 18.9,
21.5 and 18.2, and 24.5 and 20.8 for MnO, Mn2O3, Mn3O4, and
MnO2, respectively. The residues of 2 and 3 were expected to be
MnO or Mn3O4, when compared from the calculated results.
The TGA curves of 4 and 5 were not clear because the
compounds were unstable in air for sampling (Fig. 6).
Compound 4 showed a continuous weight loss at 25–500 ꢁC.
The nal residues of 4 were calculated at 51.2%, which was
a much higher value than the residual values of known
manganese nitrides (Mn3N2, Mn4N, Mn2N, MnN, Mn5N2, etc.).
These results suggested that 4 was not volatile and a large
amount of decomposed carbon remained in the residue aer
the thermal decomposition. Conversely, the TGA of 5, which is
a volatile liquid compound, revealed a like single-step weight
˚
A (Mn2–N5) for molecule 2.
The four-membered rings that were formed by the two N
atoms of the NEt2 ligands and two Mn atoms, Mn1–N3–Mn1i–
N3i and Mn2–N6–Mn2i–N6i, exhibited bond angles of 95.31(9)ꢁ
(N3–Mn1–N3i) and 84.69(9)ꢁ (Mn1–N3–Mn1i) for molecule 1
and 94.78(8)ꢁ (N6–Mn2–N6i) and 85.22(8)ꢁ (Mn2–N6–Mn2i) for
molecule 2. The lengths of the Mn–N bridging bonds of 4 were
i
˚
2.143(2) (Mn1–N3) and 2.143(2) A (Mn1–N3 ) for molecule 1, and
i
˚
2.142(2) (Mn2–N6) and 2.145(2) A (Mn2–N6 ) for molecule 2.
The coordinated bonds Mn1–N1 and Mn2–N4 were longer
than the other bonds. The lengths of the four bridged bonds
(Mn1–N3, Mn1–N3i, Mn2–N6, and Mn2–N6i) were almost the
same. The lengths and angles of the Mn–N bridging bonds for
˚
reported compounds with amido ligands were 2.078–2.189 A,
and 83.4–88.66ꢁ (Mn–N–Mn) and 92.35–96.72ꢁ (N–Mn–N).22
˚
The distance between the two Mn atoms was 2.8868(8) A for
˚
molecule 1 and 2.9025(8) A for molecule 2. These distances were
shorter than those of 1–3 because if the bulkiness or difference
in the bonding formation of the bridging ligand.
All the other bond lengths and angles of 1–4 were within the
expected ranges.
ꢁ
loss of 68.2% up to 195 C. The nal residues of 5 were calcu-
lated at 14.3%, which was a lower value than the expected
residual values of manganese nitrides (calculated residue for
Mn3N2: 18.9; Mn4N: 22.9; Mn2N: 18.2; MnN: 40.5; Mn5N2: 17.8).
The results were indirectly demonstrating that 5 was more
volatile than 1–4.
TGA curves and weight loss characteristics of 2 and 3 are
displayed in Fig. 5. A three-step weight loss was observed for 2
Among these compounds, 5 was expected to be the best
precursor for Mn-containing thin lms because it was liquid
and had a low evaporation temperature and suitable thermal
stability.
Conclusions
We
synthesized
ve
heteroleptic
compounds,
[Mn(tmhd)(TMEDA)Cl]2 (1), [Mn(tmhd)(dmamp)]2 (2), Mn2(-
tmhd)2(edpa)2(m-THF) (3), [Mn(dmampea)(NEt2)]2 (4), and
Mn(dmampea)(iPr-MeAMD) (5). Compounds 1–4 were non-
volatile solids; however, 5 was a volatile liquid distilled at
110 ꢁC under a reduced pressure of 10ꢂ1 Torr. Crystallographic
studies revealed that 1–4 were dimers bridged by two Cl atoms
(for 1), two O atoms of dmamp (for 2), two O atoms of edpa and
Fig. 5 Thermal analyses of 2 and 3.
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one O atom of THF (for 3), and two N atoms of NEt2 (for 4); the
dimers exhibited distorted octahedral, distorted trigonal
bipyramidal, distorted octahedral, and distorted tetrahedral
geometries around the Mn centers, respectively. TGA of 2 and 3
showed three-step weight losses and the residues were consid-
ered to be MnO and Mn3O4, respectively. By TGA, 4 was deter-
mined to be thermally unstable because of the signicantly
higher residue values than the predicted values of known
manganese nitrides. The TGA plot of 5 exhibited like single-step
weight loss and the residual values were lower than those ex-
pected of manganese nitrides. Compound 5 appeared as
a useful precursor for Mn-containing thin lms because it was
liquid and it exhibited low evaporation temperature and suit-
able thermal stability. We plan to investigate ALD to deposit
Mn-containing thin lms using 5 as a precursor.
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Conflicts of interest
There are no conicts to declare.
Acknowledgements
This research was supported by a grant from the Development
of Organometallics and Device Fabrication for IT ET Conver-
gence Project through the Korea Research Institute of Chemical
Technology (KRICT) of Republic of Korea (SI1703-02) and the
Development of Smart Chemical Materials for IoT Devices
Project through the Korea Research Institute of Chemical
Technology (KRICT) of Republic of Korea (SS2021-20).
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