Unusual coordination chemistry of organoaluminum and - Gallium complexes in N2S and NS coordination environments. Synthesis and crystal structure of (Me2Al)[NC5H4CMeNNC(S)NC3H 7](AlMe2)and (Me2Ga) [PhMeCNNC (S)NPh] (GaMe2)

Article abstract of DOI:10.1021/om960778m

The synthesis and characterization of the dinuclear group 13 heterocyclic carboxaldehyde thiosemicarbazone complexes (Me₂M)[NC₅H₄CMeNNC(S)NR](MMe₂) (M = Al, R = Me (1), C₃H₇ (3), Ph (5); M = Ga, R = Me (2), ⁱC₃H₇ (4), Ph (6)) and acetophenone thiosemicarbazone complexes (Me₂M)(CH₃RCNNC(S)NR′)(MMe₂) (M = Al, R = Ph, R′ = Ph (7); M = Al, R = CH₃, R′ = CH₃ (9); M = Ga, R = Ph, R′ = Ph (8); M = Ga R = CH₃, R′ = CH₃ (10)) are described. Compounds 1-6 were prepared by the reaction of MMe₃ (M = Al, Ga) with 2-acetylpyridine 4-alkylthiosemicarbazone in toluene. Compounds 7-10 were prepared using MMe₃ (M = Al, Ga) in toluene with acetophenone 4-alkylthiosemicarbazone under anaerobic conditions. These compounds, 1-10, have been characterized by microanalysis, NMR (¹H, ¹³C, ²⁷Al) spectroscopy, and single-crystal X-ray diffraction. X-ray single-crystal diffraction analyses reveal that compound 3 is a dinuclear aluminum compound with coordination numbers of five and four and compound 8 is a dinuclear gallium compound in which each gallium atom is four-coordinate.

Full text of DOI:10.1021/om960778m

2110
Organometallics 1997, 16, 2110-2115
Un u su a l Coor d in a tion Ch em istr y of Or ga n oa lu m in u m
a n d -ga lliu m Com p lexes in N2S a n d NS Coor d in a tion
En vir on m en ts. Syn th esis a n d Cr ysta l Str u ctu r e of
(Me2Al)[NC5H4CMeNNC(S)NC3H7](AlMe2) a n d
(Me2Ga )[P h MeCNNC(S)NP h ](Ga Me2)
Cheolki Paek, Sang Ook Kang,* and J aejung Ko*
Department of Chemistry, Korea University, Chochiwon, Chungnam 339-700, Korea
Patrick J . Carroll
Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
Received September 9, 1996X
The synthesis and characterization of the dinuclear group 13 heterocyclic carboxaldehyde
thiosemicarbazone complexes (Me2M)[NC5H4CMeNNC(S)NR](MMe2) (M ) Al, R ) Me (1),
iC3H7 (3), Ph (5); M ) Ga, R ) Me (2), iC3H7 (4), Ph (6)) and acetophenone thiosemicarbazone
complexes (Me2M)(CH3RCNNC(S)NR′)(MMe2) (M ) Al, R ) Ph, R′ ) Ph (7); M ) Al, R )
CH3, R′ ) CH3 (9); M ) Ga, R ) Ph, R′ ) Ph (8); M ) Ga R ) CH3, R′ ) CH3 (10)) are
described. Compounds 1-6 were prepared by the reaction of MMe3 (M ) Al, Ga) with
2-acetylpyridine 4-alkylthiosemicarbazone in toluene. Compounds 7-10 were prepared using
MMe3 (M ) Al, Ga) in toluene with acetophenone 4-alkylthiosemicarbazone under anaerobic
conditions. These compounds, 1-10, have been characterized by microanalysis, NMR (1H,
13C, 27Al) spectroscopy, and single-crystal X-ray diffraction. X-ray single-crystal diffraction
analyses reveal that compound 3 is a dinuclear aluminum compound with coordination
numbers of five and four and compound 8 is a dinuclear gallium compound in which each
gallium atom is four-coordinate.
Ch a r t 1
In tr od u ction
The terdentate heterocyclic carboxaldehyde thiosemi-
carbazones have been shown to form complexes with
various transition-metal ions, including Cu(II),1 Ni(II),2
Co(II),3 Fe(II),4 Hg(I),5 and Tl(I).5 Extensive literature
on the antitumor properties of many R-N-heterocyclic
carboxaldehyde thiosemicarbazones is now available.
The gallium(III) complexes of the heterocyclic carbox-
aldehyde thiosemicarbazones have continued to attract
attention due to the fact that the radioactive species of
gallium (67Ga) are γ-ray emitters with energies which
make them useful as medical diagnostic agents.6 Re-
cently, Kepper and co-workers7 developed gallium(III)
complexes employing ligands which themselves had
antiviral and antitumor activity, such as R-N-hetero-
cyclic carboxaldehyde thiosemicarbazones.8
We9 have recently prepared a series of trinuclear
group 13 bis(thiosemicarbazone) complexes (MeM){CH2-
[C(Me)NNC(S)(NR)]2}(MMe2)2 (M ) Al, Ga; R ) Me, Et,
Ph). However, the coordination chemistry of the thio-
semicarbazone ligands with aluminum and gallium
remains relatively unexplored. We have decided to
investigate the coordination ability of the thiosemicar-
bazone that contains a semicarbazone with one thiol
group (Chart 1, II) or alternatively one HN-CdS donor
entity (I), which should be useful for the construction
of polynuclear complexes. Since the general type of
reaction, namely evolution of an alkane from the
interaction of AlR3/GaR3 with N-H/S-H bonds, is well-
X Abstract published in Advance ACS Abstracts, April 15, 1997.
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Brodie, A. M. J . Chem. Soc., Dalton Trans. 1987, 493. (b) Ainscough,
E. W.; Brodie, A. M.; Ranford, J . D.; Waters, J . M. J . Chem. Soc., Dalton
Trans. 1991, 2125. (c) Ainscough, E. W.; Brodie, A. M.; Ranford, J .
D.; Waters, J . M. J . Chem. Soc., Dalton Trans. 1991, 1737. (d) West,
D. X.; Carlson, C. S.; Galloway, C. P.; Liberta, A. E.; Daniel, C. R.
Transition Met. Chem. 1990, 15, 91. (e) West, D. X.; Liberta, A. E.;
Rajendran, K.; Hall, I. H. Anti-Cancer Drugs 1993, 4, 241. (f)
Ainscough, E. W.; Baker, E. N.; Brodie, A. M.; Cresswell, R. J .; Ranford,
J . D. Inorg. Chim. Acta 1990, 172, 185. (g) West, D. X.; Carlson, C.
S.; Liberta, A. E.; Scovill, J . P. Transition Met. Chem. 1990, 15, 383.
(2) (a) West, D. X.; Carlson, C. S.; Liberta, A. E.; Albert, J . N.; Daniel,
C. R. Transition Met. Chem. 1990, 15, 341. (b) Mathew, M.; Palenik,
G. J . J . Am. Chem. Soc. 1969, 91, 6310.
(3) (a) West, D. X.; Carlson, C. S.; Whyte, A. C.; Liberta, A. E.
Transition Met. Chem. 1990, 15, 43. (b) Grag, A.; Tandon, J . P. Synth.
React. Inorg. Met-Org. Chem. 1988, 18, 705.
(4) (a) Raina, R.; Srivastava, T. S. Inorg. Chim. Acta 1982, 67, 83.
(b) Beraldo, H.; Tosi, L. Inorg. Chim. Acta 1983, 75, 249.
(5) Casas, J . C.; Castano, M. V.; Rodriguez-Arguelles, M. C.;
Sanchez, A.; Sordo, J . J . Chem. Soc., Dalton Trans. 1993, 1253.
(6) (a) Moerlein, S. M.; Welch, M. J . Int. J . Nucl. Med. Biol. 1981,
8, 277. (b) Edwards, G. L.; Hayes, R. L. J . Nucl. Med. 1969, 10, 103.
(7) Kratz, F.; Nuber, B.; Weiss, J .; Keppler, B. K. Synth. React. Inorg.
Met.-Org. Chem. 1991, 21, 1601.
(8) (a) French, F. A.; Blanz, E. J .; DoAmaral, J . R.; French, D. A. J .
Med. Chem. 1970, 13, 1117. (b) Saryan, L. A.; Ankel, E.; Krishnamurti,
C.; Pefering, D. H. J . Med. Chem. 1979, 22, 1218. (c) Klayman, D. L.;
Bartosevich, J . F.; Griffin, T. S.; Mason, C. J .; Scovill, J . P. J . Med.
Chem. 1979, 22, 855. (d) Scovill, J . P.; Klayman, D. L.; Franchino, C.
F. J . Med. Chem. 1982, 25, 1261.
(9) Paek, C.; Kang, S. O.; Ko, J .; Carroll, P. J . Organometallics 1997,
16, 1503.
S0276-7333(96)00778-9 CCC: $14.00 © 1997 American Chemical Society

Organoaluminum and -gallium Complexes
Organometallics, Vol. 16, No. 10, 1997 2111
established for both the open chain10 and closed mac-
rocyclic systems,11 the R-N-heterocyclic carboxaldehyde
thiosemicarbazone ligand is valuable in the preparation
of alkyl complexes of group 13 organometallic species.
Motivated by an interest in the specific effects of the
R-N-heterocyclic carboxaldehyde thiosemicarbazone ge-
ometry on the coordination environments of aluminum
and gallium, we began a systematic study of the use of
terdentate and acetophenone thiosemicarbazone ligands
for organometallic aluminum and gallium compounds.
We report here the interaction of trimethylaluminum
and -gallium with the N,N,S-terdentate ligand acetyl-
pyridine thiosemicarbazone and the N,S-bidentate ligand
acetophenone thiosemicarbazone.
(w), 983 (w), 829 (w), 774 (m), 735 (w), 640 (br). Anal. Calcd
for C13H22N4SAl2: C, 48.74; H, 6.92. Found: C, 48.42; H, 6.88.
(Me2Ga )[NC5H4C(CH3)NNC(S)NMe](Ga Me2) (2). Mp:
168 °C. 1H NMR (C6D6, 25 °C): δ 7.85 (m, 1H, Py), 6.81 (m,
1H, Py), 6.48 (m, 1H, Py), 6.39 (m, 1H, Py), 3.18 (s, 3H, NCH3),
1.75 (s, 3H, CCH3), 0.33 (s, 6H, GaCH3), -0.09 (s, 6H, GaCH3).
13C{1H} NMR (C6D6, 25 °C): δ 175.84 (CS), 148.94 (C(CH3)N),
145.84, 137.91, 137.24, 122.99, 120.43 (CH, Py), 31.90 (NCH3),
14.28 (CCH3), -1.31 (GaCH3), -6.07 (GaCH3). IR (KBr pellet;
cm-1): 2983 (br), 1581 (w), 1550 (br), 1535 (br), 1485 (br), 1434
(s), 1385 (s), 1370 (sh), 1323 (w), 1282 (w), 1268 (w), 1227 (s),
1179 (s), 1148 (m), 1135 (w), 1102 (m), 1081 (w), 1037 (w), 1006
(w), 971 (w), 860 (w), 828 (s), 770 (s), 740 (m), 729 (w), 676
(w), 631 (w). MS (EI): m/ z 405 [M+], 206 [M+ - 4GaMe3].
Anal. Calcd for C13H22N4SGa2: C, 38.47; H, 5.47. Found: C,
38.29; H, 5.28.
(Me2Al)[NC5H4C(CH3)NNC(S)NC3H7](AlMe2) (3). Mp:
139 °C (dec). 1H NMR (C6D6, 25 °C): δ 7.93 (m, 1H, Py), 6.70
(m, 1H, Py), 6.27 (m, 2H, Py), 4.29 (sept, J ) 6.48 Hz, 1H,
CH), 1.70 (s, 3H, CH3), 1.19 (d, J ) 6.48 Hz, 6H, CH3), -0.05
(s, 6H, AlCH3), -0.22 (s, 6H, AlCH3). 13C{1H} NMR (C6D6, 25
°C): δ 185.85 (CS), 148.23 (C(CH3)N), 146.02, 139.44, 138.80,
123.17, 119.74 (CH, Py), 23.52 (NCH3), 14.27 (CHCH3), 13.61
(CHCH3), -0.04 (AlCH3), -8.76 (AlCH3). 27Al NMR: δ 152,
114. IR (KBr pellet; cm-1): 2938 (w), 2880 (w), 1590 (w), 1506
(s), 1494 (sh), 1450 (m), 1420 (s), 1373 (w), 1356 (w), 1304 (w),
1289 (w), 1200 (w), 1190 (sh), 1173 (br), 1142 (m), 1112 (w),
1105 (w), 1076 (w), 1041 (w), 1014 (w), 994 (w), 980 (w), 850
(br), 798 (w), 775 (m), 741 (w), 732 (w), 650 (w). Anal. Calcd
for C15H26N4SAl2: C, 51.71; H, 7.52. Found: C, 51.34; H, 7.38.
Exp er im en ta l Section
Gen er a l P r oced u r es. All manipulations were performed
under a dry, oxygen-free, dinitrogen or argon atmosphere using
standard Schlenk techniques or in a Vacuum Atmosphere HE-
493 drybox. Toluene and hexane were freshly distilled from
sodium/benzophenone prior to use. All 1H, 13C, and 27Al NMR
spectra were measured on a Bruker WH-300 spectrometer.
Chemical shifts were referenced relative to either TMS (1H)
or benzene-d6 (1H, δ 7.155; 13C{1H}, δ 128.00), while 27Al NMR
spectra were referenced relative to Al(H2O)63+. IR spectra were
recorded on a Shimadzu FT-IR-8501 spectrometer. Mass
spectra were recorded on a high-resolution VG 70-VSEG
instrument, and elemental analyses were performed by the
Basic Science Center. The ligands [NC5H4CRNNHC(S)NHR′]
(R ) CH3; R′ ) CH3, C3H7, C6H5) were prepared according to
the literature methods.8d AlMe3 and GaMe3 were purchased
from Strem Chemicals.
Gen er a l Syn th esis of (Me2M)[NC5H4C(CH3)NNC(S)NR]-
(MMe2) a n d (Me2M)[P h MeCNNC(S)NR](MMe2). In a typi-
cal synthesis, a solution of 2-acetylpyridine 4-methylthiosemi-
carbazone (2.0 mmol) in toluene (10 mL) was treated with
MMe3 (4 mmol) at room temperature. The stirred mixture was
warmed to 35 °C, during which the suspension dissolved. The
resulting yellow solution was stirred at that temperature for
2 h and then allowed to cool to 25 °C. The solution was layered
with hexane (3 mL) and stored at -15 °C for 1 day, whereupon
yellow crystals formed in 85-95% yield.
(Me2Ga )[NC5H4C(CH3)NNC(S)NC3H7](Ga Me2) (4). Mp:
162 °C. 1H NMR (C6D6, 25 °C): δ 7.94 (m, 1H, Py), 6.83 (m,
1H, Py), 6.64 (m, 1H, Py), 6.41 (m, 1H, Py), 4.41 (sept, J )
6.36 Hz, 1H, CH), 2.22 (s, 3H, CH3), 0.95 (d, J ) 6.36 Hz, 6H,
CH(CH3)2), 0.39 (s, 6H, GaCH3), -0.12 (s, 6H, GaCH3). 13C-
{1H} NMR (C6D6, 25 °C): δ 186.21 (CS), 149.67 (C(CH3)N),
144.28, 139.21, 137.91, 123.13, 120.68 (CH, Py), 22.63 (NCH3),
14.66 (CHCH3), 13.14 (CHCH3), -0.03 (GaCH3), -5.24 (GaCH3).
IR (KBr pellet; cm-1): 3309 (s), 2940 (w), 2890 (br), 1584 (m),
1499 (w), 1480 (w), 1425, (s), 1322 (w), 1298 (m), 1282 (w),
1232 (s), 1170 (m), 1150 (m), 1140 (w), 1085 (w), 1073 (w), 1040
(w), 881 (w), 850 (m), 820 (m), 772 (m), 760 (w), 740 (br), 662
(w), 636 (w). Anal. Calcd for C15H26N4SGa2: C, 41.54; H, 5.99.
Found: C, 41.22; H, 5.68.
(Me2Al)[NC5H4C(CH3)NNC(S)NMe](AlMe2) (1). Mp: 148
°C (dec). 1H NMR (C6D6, 25 °C): δ 7.95 (m, 1H, Py), 6.72 (m,
1H, Py), 6.35 (m, 1H, Py), 6.25 (m, 1H, Py), 3.20 (s, 3H, NCH3),
1.68 (s, 3H, CCH3), -0.05 (s, 6H, AlCH3), -0.47 (s, 6H, AlCH3).
13C{1H} NMR (C6D6, 25 °C): δ 189.16 (CS), 149.92 (C(CH3)N),
145.94, 143.58, 138.41, 122.10, 119.90 (CH, Py), 30.10 (NCH3),
11.94 (CCH3), -0.03 (AlCH3), -4.87 (AlCH3). 27Al NMR: δ
153 (w1/2 ) 3680 Hz), 109 (w1/2 ) 2544 Hz). IR (KBr pellet;
cm-1): 2946 (w), 1535 (m), 1523 (s), 1508 (sh), 1485 (w), 1450
(w), 1422 (w), 1391 (br), 1287 (w), 1246 (w), 1225 (m), 1160
(w), 1140 (w), 1130 (w), 1097 (w), 1046 (w), 1042 (w), 1035
(Me2Al)[NC5H4C(CH3)NNC(S)NC6H5](AlMe2) (5). Mp:
143 °C (dec). 1H NMR (C6D6, 25 °C): δ 7.84 (m, 1H, py), 7.52
(m, 2H, Ph), 7.25 (m, 2H, Ph), 7.03 (m, 1H, Ph), 6.72 (m, 1H,
py), 6.32 (m, 2H, py), 1.78 (s, 3H, CH3), 0.47 (s, 6H, AlCH3),
-0.41 (s, 6H, AlCH3). 13C{1H} NMR (C6D6, 25 °C): δ 175.47
(CS), 147.59 (C(CH3)N), 146.35, 145.29, 144.22, 139.13, 127.68,
126.31, 125.63, 124.35, 121.01, 12.76 (CCH3), -6.11 (AlCH3),
-7.79 (AlCH3). IR (KBr pellet; cm-1): 2890 (w), 1580 (m), 1500
(br), 1470 (s), 1427 (s), 1046 (sh), 1376 (w), 1328 (w), 1290 (w),
1256 (w), 1240 (br), 1165 (s), 1095 (w), 1059 (w), 1018 (w), 985
(br), 942 (w), 920 (w), 815 (br), 769 (m), 688 (br), 655 (w). MS
(EI): m/ z 382 [M+], 268 [M+ - 4AlMe3]. Anal. Calcd for
(10) (a) Robinson, G. H.; Sangokoya, S. A. J . Am. Chem. Soc. 1987,
109, 6852. (b) Del Piero, G.; Cesari, M.; Cucinella, S.; Mazzei, A. J .
Organomet. Chem. 1977, 137, 265. (c) Cucinella, S.; Dozzi, G.; Perego,
G.; Mazzei, A. J . Organomet. Chem. 1977, 137, 257. (d) Del Piero, G.;
Perogo, G.; Cucinella, S.; Cesari, M.; Mazzei, A. J . Organomet. Chem.
1977, 136, 13. (e) Li, Y.; Martell, A. E.; Hancock, R. D.; Reibenspies,
J . H.; Anderson, C. J .; Welch, M. J . Inorg. Chem. 1996, 35, 404. (f)
Atwood, D. A.; J egier, J . A.; Rutherford, D. Inorg. Chem. 1996, 35, 63.
(g) Atwood, D. A.; Rutherford, D. Organometallics 1995, 14, 2880. (h)
Robinson, G. H.; Sangokoyo, S. A.; Moise, F.; Pennington, W. T.; Welch,
M. J . Organometallics 1988, 7, 1887. (i) Moore, D. A.; Fanwick, P. E.;
Welch, M. J . Inorg. Chem. 1990, 29, 672.
(11) (a) Robinson, G. H.; Rae, A. D.; Campana, C. F.; Byram, S. K.
Organometallics 1987, 6, 1227. (b) Robinson, G. H.; Sangokoyo, S. A.
Organometallics 1988, 7, 1453. (c) Goedken, V. L.; Ito, H.; Ito, T. J .
Chem. Soc., Chem. Commun. 1984, 1453. (d) Robinson, G. H.; Self,
M. F.; Sangokoya, S. A.; Pennington, W. T. J . Am. Chem. Soc. 1989,
111, 1520. (e) Robinson, G. H.; Hunter, W. E.; Bott, S. G.; Atwood, J .
L. J . Organomet. Chem. 1987, 326, 9.
C
18H24N4SAl2: C, 56.54; H, 6.28. Found: C, 56.22; H, 5.95.
(Me2Ga )[NC5H4C(CH3)NNC(S)NC6H5](Ga Me2) (6). Mp:
168-172 °C. 1H NMR(C6D6, 25 °C): δ 7.35 (m, 1H, py), 7.11-
7.34 (m, 1H, Ph), 6.76-6.87 (m, 3H, Ph), 6.62 (m, 1H, Ph),
6.13 (m, 1H, py), 6.00 (m, 1H, py), 1.44 (s, 3H, CH3), -0.07 (s,
6H, GaCH3), -0.41 (s, 6H, Ga-CH3). 13C{1H} NMR (C6D6, 25
°C): δ 177.35 (CS), 150.78, 148.91, 145.72, 140.72, 138.04,
136.35, 127.68, 125.66, 123.88, 122.83, 121.39, 15.29 (CCH3),
-0.08 (GaCH3), -5.07 (GaCH3). IR (KBr pellet; cm-1): 2939
(w), 1590 (m), 1484 (m), 1445 (m), 1419 (s), 1312 (w), 1249
(m), 1191 (w), 1182 (w), 1149 (m), 1100 (w), 1080 (w), 1068
(w), 1042 (w), 1036 (w), 1010 (br), 946 (w), 892 (w), 854 (w),
832 (w), 812 (w), 775 (m), 746 (m), 740 (sh), 700 (w), 689 (w),
672 (br), 655 (w), 636 (w), 620 (br). Anal. Calcd for C18H24N4-
SGa2: C, 46.20; H, 5.13. Found: C, 45.86; H, 4.92.

2112 Organometallics, Vol. 16, No. 10, 1997
Paek et al.
Ta ble 1. Cr ysta llogr a p h ic Da ta for th e Str u ctu r a l
Stu d ies of Com p ou n d s 3 a n d 8
(Me2Al)[MeP h CNNC(S)NC6H5](AlMe2) (7). Mp: 148 °C.
1H NMR (C6D6, 25 °C): δ 7.49 (m, 2H, Ph), 7.33 (m, 2H, Ph),
7.09-7.16 (m, 4H, Ph), 6.91-6.97 (m, 4H, Ph), 2.11 (s, 3H,
CH3), -0.07 (s, 6H, AlCH3), -0.71 (s, 6H, AlCH3). 13C{1H}
NMR(C6D6, 25 °C): δ 180.17 (CS), 165.61 (CN), 161.36, 143.95,
137.23, 131.26, 126.26, 125.79, 22.07 (CH3), -6.52 (AlCH3),
-8.49 (AlCH3). 27Al NMR: δ 148 (w1/2 ) 2262 Hz). IR (KBr
pellet; cm-1): 3050 (w), 2825 (w), 1598 (w), 1537 (sh), 1525
(s), 1484 (w), 1449 (w), 1362 (w), 1312 (sh), 1285 (br), 1260
(w), 1182 (m), 1157 (sh), 1103 (w), 1062 (w), 1025 (w), 1000
(w), 975 (w), 930 (w), 793 (w), 764 (m), 730 (w), 694 (w). Anal.
Calcd for C19H25N3SAl2: C, 59.82; H, 6.18. Found: C, 59.51;
H, 6.02.
3
8
empirical formula
fw
cryst class
space group
a, Å
C15H26N4SAl2
348.42
triclinic
P1h
15.337(3)
16.951(3)
8.794(2)
96.03(1)
91.10(1)
74.81(1)
2194.2(9)
1.12
744
4
2.33
6775
3695
2.30
0.068
0.076
C19H25N3SGa2
466.93
monoclinic
P21/c
12.5180(3)
8.9768(4)
19.1100(6)
b, Å
c, Å
R, deg
â, deg
102.700(3)
γ, deg
V, Å3
2145.7500
(Me2Ga )[MeP h CNNC(S)NC6H5](Ga Me2) (8). Mp: 136
°C. 1H NMR (C6D6, 25 °C): δ 7.38-7.42 (m, 2H, Ph), 7.12-
7.17 (m, 4H, Ph), 6.92-7.02 (m, 4H, Ph), 2.03 (s, 3H, CH3),
0.31 (s, 6H, GaCH3), -0.33 (s, 6H, GaCH3). 13C{1H} NMR
(C6D6, 25 °C): δ 178.88 (CS), 167.59 (CN), 140.65, 138.32,
130.30, 126.47, 125.56, 123.49, 122.94, 122.61, 120.42, 22.73
(CH3), -1.88 (GaCH3), -5.06 (GaCH3). IR (KBr pellet; cm-1):
2900 (w), 2825 (w), 1595 (w), 1580 (w), 1575 (w), 1510 (sh),
1502 (s), 1491 (s), 1480 (s), 1448 (w), 1368 (w), 1330 (m), 1316
(w), 1280 (w), 1264 (w), 1230 (s), 1203 (w), 1186 (w), 1178 (w),
1151 (w), 1120 (w), 1075 (w), 1052 (w), 1018 (w), 1000 (w),
967 (w), 950 (m), 925 (w), 908 (w), 850 (w), 837 (w), 818 (w),
766 (m), 742 (m), 730 (w), 700 (s), 660 (m), 638 (w), 618 (w).
MS (EI): m/ z 467 [M+], 437 [M+ - 2CH3]. Anal. Calcd for
Dc, g cm-3
F(000)
1.445
226
4
Z
µ(Mo KR), cm-1
total no. of reflns
no. of obsd reflns
goodness of fit
R1a
16 435
2797
1.53
0.0425
0.0566
wR2a
a
2
R1 ) ∑||Fo| - |Fc||/∑|Fo|; wR2 ) {∑[w(Fo - Fc2)2]/∑[wFo2]}1/2
.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Com p ou n d 3
Al(1)-S(11)
S(11)-C(10)
Al(3)-S(31)
S(31)-C(30)
Al(1)-N(1)
Al(1)-N(8)
Al(1)-C(17)
Al(1)-C(18)
Al(2)-N(9)
Al(2)-N(12)
Al(2)-C(19)
Al(2)-C(20)
Al(3)-N(21)
Al(3)-N(28)
Al(3)-C(37)
Al(3)-C(38)
Al(4)-N(29)
2.491(3)
1.691(6)
2.487(2)
1.709(5)
2.076(5)
2.040(5)
1.962(7)
1.947(7)
1.946(5)
1.915(5)
1.953(7)
1.939(7)
2.088(5)
2.057(5)
1.951(7)
1.977(7)
1.953(5)
Al(4)-N(32)
Al(4)-C(39)
Al(4)-C(40)
N(1)-C(2)
1.913(5)
1.946(8)
1.928(8)
1.339(8)
1.351(7)
1.362(6)
1.320(7)
1.380(7)
1.318(7)
1.463(7)
1.339(7)
1.356(7)
1.349(6)
1.299(6)
1.380(7)
1.309(7)
1.466(7)
C
19H25N3SGa2: C, 48.87; H, 5.41. Found: C, 48.38; H, 5.23.
(Me2Al)[Me2CNNC(S)NCH3](AlMe2) (9). Mp: 118-120
°C (dec). 1H NMR (C6D6, 25 °C): δ 2.76 (s, 3H, CH3), 1.42 (s,
3H, CH3), 1.27 (s, 3H, CH3), -0.19 (s, 6H, AlCH3), -0.56 (s,
6H, AlCH3). 13C{1H} NMR(C6D6, 25 °C): δ 180.24 (CS), 158.15
(CN), 33.24 (NCH3), 23.86 (CCH3), 21.68 (CCH3), -6.59
(AlCH3), -10.88 (AlCH3). 27Al NMR: δ 150 (w1/2 ) 2314 Hz).
IR (KBr pellet; cm-1): 3240 (br), 1550 (s), 1538 (sh), 1475 (m),
1450 (br), 1430 (w), 1404 (w), 1366 (w), 1344 (w), 1267 (m),
1226 (s), 1165 (br), 1103 (w), 1095 (w), 1060 (w), 1044 (w), 1017
(w), 1008 (w), 900 (w), 850 (w), 769 (m), 744 (w), 710 (w), 660
(w). Anal. Calcd for C9H21N3SAl2: C, 42.00; H, 8.24. Found:
C, 41.62; H, 8.02.
N(1)-C(6)
N(8)-N(9)
N(8)-C(7)
N(9)-C(10)
N(12)-C(10)
N(12)-C(13)
N(21)-C(22)
N(21)-C(26)
N(28)-N(29)
N(28)-C(27)
N(29)-C(30)
N(32)-C(30)
N(32)-C(33)
(Me2Ga )[Me2CNNC(S)NCH3](Ga Me2) (10). Mp: 64-66
°C. 1H NMR (C6D6, 25 °C): δ 2.90 (s, 3H, CH3), 1.37 (s, 3H,
CH3), 1.26 (s, 3H, CH3), 0.21 (s, 6H, GaCH3), -0.21 (s, 6H,
Ga-CH3). 13C{1H} NMR (C6D6, 25 °C): δ 179.24 (CS), 170.34,
162.33 (CN), 33.64 (NCH3), 23.65 (CCH3), -3.10 (GaCH3),
-7.37 (GaCH3). IR (KBr pellet; cm-1): 2940 (br, w), 2872 (br,
w), 1608 (w), 1504 (s), 1485 (s), 1449 (w), 1430 (w), 1393 (m),
1370 (w), 1366 (w), 1280 (w), 1250 (m), 1211 (w), 1198 (w),
1190 (w), 1167 (m), 1156 (w), 1119 (w), 1012 (w), 985 (w), 963
(br, w), 851 (w), 840 (w), 790 (m), 730 (br, w), 699 (br, w), 660
(w). Anal. Calcd for C9H21N3SGa2: C, 31.53; H, 6.19.
Found: C, 31.14; H, 5.92.
X-r a y Cr ysta llogr a p h y. Details of the crystal data and a
summary of intensity data collection parameters for 3 and 8
are given in Table 1. The crystals of 3 and 8 were grown from
a toluene/hexane solution at -15 °C. The crystals of 3 and 8
were mounted in thin-walled glass capillaries and sealed under
argon. The data sets of 3 and 8 were collected using a Rigaku/
RAXIS IIa area detector employing graphite-monochromated
Mo KR radiation (λ ) 0.710 96 Å) at a temperature of 253 K.
The structure were solved by direct methods. Refinements
were by full-matrix least-squares techniques based on F to
minimize the quantity Σw(|Fo| - |Fc|)2 with w ) 1/σ2(F). Non-
hydrogen atoms of 3 and 8 were anisotropically refined, and
hydrogen atoms were isotropically refined. The hydrogen
atoms of 3 and 8 were included as constant contributions to
the structure factors. The refinement of 3 converged to R1 )
0.068 and wR2 ) 0.076 and that of 8 converged to R1 ) 0.0425
and wR2 ) 0.0566. Selected bond distances and angles for 3
and 8 are given in Tables 2 and 3, respectively. The molecular
structure of compounds 3 and 8 are given in Figures 1 and 2,
respectively.
Al(1)-S(11)-C(10
S(11)-Al(1)-N(1)
S(11)-Al(1)-N(8)
S(11)-Al(1)-C(17)
S(11)-Al(1)-C(18)
N(1)-Al(1)-N(8)
N(1)-Al(1)-C(17)
N(1)-Al(1)-C(18)
N(8)-Al(1)-C(17)
N(8)-Al(1)-C(18)
95.7(2) N(12)-Al(2)-C(20)
156.5(2) C(19)-Al(2)-C(20)
80.1(2) Al(1)-N(1)-C(2)
97.4(2) Al(1)-N(1)-C(6)
97.1(2) C(2)-N(1)-C(6)
76.4(2) Al(1)-N(8)-N(9)
94.5(3) Al(1)-N(8)-C(7)
93.8(3) N(9)-N(8)-C(7)
119.6(3) Al(2)-N(9)-N(8)
118.6(3) Al(2)-N(9)-C(10)
115.9(3)
118.0(3)
124.8(4)
116.4(4)
118.8(5)
123.6(4)
118.5(4)
117.8(5)
151.5(4)
91.6(4)
C(17)-Al(1)-C(18) 121.5(3) N(8)-N(9)-C(10)
116.7(5)
94.9(4)
142.0(4)
N(9)-Al(2)-N(12)
N(9)-Al(2)-C(19)
N(9)-Al(2)-C(20)
67.7(2) Al(2)-N(12)-C(10)
113.2(3) Al(2)-N(12)-C(13)
117.5(3) C(10)-N(12)-C(13) 123.0(5)
N(12)-Al(2)-C(19) 114.6(3)
Resu lts a n d Discu ssion
Syn th esis an d Ch ar acter ization of (Me2M)[NC5H4-
CMeNNC(S)NR ](MMe2) (M ) Al, Ga ; R ) CH3,
iC3H7, C6H5) P r ep a r ed via th e Meth a n e Elim in a -
tion Reaction . The reaction of 2-acetylpyridine 4-alkyl-
thiosemicarbazone with trimethylaluminum or gallium
in toluene at 35 °C affords the corresponding organoalu-
minum or gallium complexes, in which two hydrogen
atoms have been lost from the aza hydrogen atoms via
the methane elimination reaction (eq 1). The resulting
yellow compounds 1-6 were isolated as air-sensitive
crystalline solids in a nearly quantitative yield. These
complexes are virtually insoluble in hexane but soluble
in benzene, toluene, and THF. The complexes 1-6 have

Organoaluminum and -gallium Complexes
Organometallics, Vol. 16, No. 10, 1997 2113
Ta ble 3. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Com p ou n d 8
Ga(1)-N(2)
Ga(1)-S(1)
Ga(1)-C(10)
Ga(1)-C(11)
Ga(2)-N(1)
Ga(2)-N(3)
Ga(2)-C(12)
2.033(3)
2.378(1)
1.953(6)
1.961(7)
2.070(3)
1.996(4)
1.965(6)
Ga(2)-C(13)
S(1)-C(9)
N(1)-N(2)
N(1)-C(7)
N(2)-C(9)
N(3)-C(9)
N(3)-C(14)
1.940(6)
1.747(5)
1.401(5)
1.281(6)
1.363(6)
1.318(5)
1.421(6)
S(1)-Ga(1)-N(2)
S(1)-Ga(1)-C(10)
S(1)-Ga(1)-C(11)
N(2)-Ga(1)-C(10)
N(2)-Ga(1)-C(11)
70.3(1) C(12)-Ga(2)-C(13) 129.9(3)
113.4(2) Ga(1)-S(1)-C(9)
113.4(2) Ga(2)-N(1)-N(2)
115.9(2) Ga(2)-N(1)-C(7)
110.7(2) N(2)-N(1)-C(7)
78.6(2)
111.2(3)
128.3(3)
119.8(3)
145.5(3)
101.1(3)
113.3(3)
112.6(3)
121.8(3)
124.9(4)
C(10)-Ga(1)-C(11) 122.0(3) Ga(1)-N(2)-N(1)
N(1)-Ga(2)-N(3)
N(1)-Ga(2)-C(12)
N(1)-Ga(2)-C(13)
N(3)-Ga(2)-C(12)
N(3)-Ga(2)-C(13)
79.8(1) Ga(1)-N(2)-C(9)
109.2(2) N(1)-N(2)-C(9)
107.8(2) Ga(2)-N(3)-C(9)
105.2(2) Ga(2)-N(3)-C(14)
113.7(2) C(9)-N(3)-C(14)
F igu r e 2. Molecular structure of (Me2Ga)[PhMeCNNC-
(S)NPh](GaMe2) (8). The thermal ellipsoids are drawn at
the 30% probability level.
served for five-coordinate Al atoms.14 The 1H NMR
spectrum of 3 shows two peaks at -0.05 and -0.22 ppm
due to the hydrogen atoms of the Al-Me groups. The
chemical shifts of these two kinds of Al-Me groups are
consistent with prior observations of five- and four-
coordinate Al atoms.10a,15 The finding that the peak of
Al-Me in a N2S coordination environment appears at
higher field compared with that of Al-Me in a N2
environment is consistent with the expected greater
shielding of H on the Al-CH3 group, as the two N, one
S, and two C atoms provide a more electron-rich
environment to Al(1) than that of Al(2), which is bonded
to two N and two C atoms. The 13C NMR spectrum of
3 also shows two peaks at -0.04 and -8.76 ppm due to
the carbon atoms of the Al-CH3 group in five- and four-
coordinate environments. The carbons (C(8), C(6))
attached to the imine groups appear at 185.85 and
148.23 ppm in the 13C NMR spectrum. The infrared
spectrum of 3 indicates the mode of the ligand coordina-
tion to the aluminum moiety. The peak at 1590 cm-1
is assigned to the ring deformation mode. A positive
shift in the mode compared to that of the ligand
indicates that the pyridyl nitrogen coordinates in the
complex. The stretching mode of ν(CS) at 775 cm-1 is
significantly decreased. This could involve a tautom-
erism for the semicarbazone-3-thiol, i.e., a 1,3-proton
shift (I-II).
Figu r e 1. Molecular structure of (Me2Al)[NC5H4CMeNNC-
(S)NC3H7](AlMe2) (3). The thermal ellipsoids are drawn
at the 50% probability level.
Syn th esis a n d Ch a r a cter iza tion of (Me2M)[RMe-
CNNC(S)NR′](MMe2) (M ) Al, Ga ; R ) CH3, C6H5;
R′ ) CH3, C6H5). The acetophenone thiosemicarbazone
complexes of trimethylaluminum and gallium were
synthesized using relatively straightforward reactions
with toluene as the reaction solvent (eq 2). The com-
plexes 7-10 are yellow crystalline solids at room
1
been characterized by H, 13C, and 27Al NMR, IR, and
elemental analyses. The structure of compound 3 was
determined based on its X-ray crystal structure. The
27Al spectrum of 3 shows two distinct peaks at 152 (w1/2
) 3764 Hz) and 114 (w1/2 ) 2672 Hz) ppm. The 152
ppm peak is characteristic of a four-coordinate Al atom,
when compared with the shift of the four-coordinate Al
atom in complexes of [R2AlR′]2 (R ) Me, Et; R′ ) NEt2,
OMe2, OEt2, etc.)12 and [Al(CH3C(CH2NH)3)2(Al(C-
H3)2)3].13 The 114 ppm resonance is assigned to the five-
coordinate Al(1). This value is within the range ob-
(12) Benn, R.; Rufinsky, B.; Lehmkuhl, H.; J anssen, E.; Kruger, C.
Angew. Chem., Int. Ed. Engl. 1983, 10, 779.
(13) Li, M.-D.; Chang, C.-C.; Liu, S.-T.; Lee, G.-H.; Wang, Y.; Peng,
S.-M. Organometallics 1994, 13, 1504.
(14) J iang, Z.; Interante, L. V.; Kwon, D.; Tham, F. S.; Kullnig, R.
Inorg. Chem. 1991, 30, 995.
(15) Atwood, D. A.; Rutherford, D. Organometallics 1995, 14, 2880.

2114 Organometallics, Vol. 16, No. 10, 1997
Paek et al.
from occupying exact tbp positions. The distorted
geometry was found in other structural reports of the
neutral five-coordinate organoaluminum complexes.16
The Al(1)-S(11) distance (2.491(3) Å) is comparable to
that observed for K[Al2(CH3)6SCN] (2.489(2) Å)17 and
[Al(CH3)3]4[14]aneS4 (2.522(2) Å).18 The pyridyl Al(1)-
N(1) distance (2.076(5) Å) is slightly longer than the
amido Al(1)-N(8) distance (2.040(5) Å), a feature con-
sistent with the literature.19 The Al(1)-C(17) bond
distance (1.962(7) Å) falls well within the range com-
monly found for five-coordinate aluminum complexes.14,16
The other Al(2) atom is in the AlN2C units. The
geometry about the aluminum atom, Al(2), can be
described as a distorted tetrahedron. The N(9)-Al(2)-
N(12) angle is extremely restricted by the N2C ring,
67.7(2)°. However, the C(19)-Al(2)-C(20) angle trans
to it is 118.0(3)°. The methyl ligands are rotated away
from the nitrogen donor atoms, giving an average
C-Al-N angle of 115.2(3)°. The imine N(9)-Al(2) bond
distance (1.946(5) Å) is longer than the amido N(12)-
Al(2) distance (1.915(5) Å), indicating that the nega-
tively charged amido nitrogen atom is a stronger donor
to the aluminum center than the neutral imine nitrogen
atom. The proximity of the amido nitrogen atom to the
aluminum atom appears to be the reason for the
asymmetric arrangement.
temperature, which are soluble in benzene, toluene, and
THF. The initial indication of a dinuclear formulation
for 8 stemmed from the observation of a parent ion in
the mass spectrum at m/ z 467, followed by a series of
fragmentations attributable to the loss of Me groups.
The dinuclear nature of the proposed structure was
1
indicated by the H and 13C NMR spectral equivalence
of the GaMe2 moieties. Both the 1H and 13C NMR
spectra of 8 exhibited two Ga-CH3 resonances due to
the methyl groups on the Ga(1) and Ga(2) atoms.
Confirmation of the dinuclear structure of 8 was pro-
vided by X-ray crystallography.
Descr ip tion of th e Molecu la r Str u ctu r e of (Me2-
Al)[NC5H4C(CH3)NNC(S)NC3H7](AlMe2) (3). Crys-
tals of 3 suitable for an X-ray diffraction study were
grown from toluene at -15 °C, and the structure of 3
Molecu la r Str u ctu r e Desor p tion of (Me2Ga )-
[P h MeCNNC(S)NP h ](Ga Me2) (8). A crystal of 8
suitable for X-ray diffraction study was grown from
toluene at -15 °C. A summary of the data collection
and crystallographic parameters for 8 is given in Table
1. The relevant bond lengths and angles are shown in
Table 3. The molecular structure of 8 is given in Figure
2. The molecule contains one GaN2C2 five-membered
ring and one GaCNS four-membered ring. In the solid
state, the Ga(1) center is coordinated by two nitrogen
atoms and two methyl groups in a distorted tetrahedral
configuration. The imine N(1)-Ga(2) distance (2.070-
(3) Å) is slightly longer than the amido N(3)-Ga(2)
distance (1.996(4) Å). Significant distortion from an
ideal tetrahedral geometry is observed for the gallium
atom, Ga(1), in the constrained four-membered ring; the
ring angle at aluminum is 70.3(1)°. The Ga(1)-S(1)
bond distance (2.378(1) Å) is slightly longer than that
observed for [py(tBu)GaS]3 (2.231(3)-2.253(3) Å)20 and
for the thiolate-bridged complexes Ga4I4(SME)4S2 (2.204-
(8) Å).21 However, the Ga(1)-S(1) and Ga(1)-N(2)
(2.033(3) Å) bond distances in 8 are comparable to those
of the pyridine-2-thiol complex Ga2(OEt)2(2-C5H4NS)4
(Ga-S ) 2.431(2) Å; Ga-N ) 2.100(4) Å) and Ga-
(SC5H4N)3 (Ga-S ) 2.420(3) Å; Ga-N ) 2.062(8) Å).22
The relatively long Ga(1)-S(1) and Ga(1)-N(2) bond
was determined from data collected at -120 °C.
A
summary of the data collection and crystallographic
parameters are given in Table 1. Selected bond lengths
and angles are given in Table 2. An ORTEP diagram
of the solid state structure giving the atom-numbering
scheme used in the tables is shown in Figure 1.
The single-crystal structure of compound 3 indicates
an asymmetric unit containing two unique molecules,
which reside in general positions. The two molecules
are almost identical in conformation and absolute
configuration, but differ slightly in bond distances and
angles. No symmetric element can be found in these
structures. Coordinates for three carbon atoms with
very high thermal motions are present. These three
peaks lie near an inversion center and represent a
poorly behaving hexane molecule. Al(1) and Al(3) are
each included in both the AlN2C2 and AlN2CS five-
membered rings, while Al(2) and Al(4) are part of the
AlN2C four-membered ring.
Several points are worthy of note regarding the
structure and bonding in 3. Compound 3 contains two
types of organoaluminum moieties with different coor-
dination environments. The aluminum atom, Al(2), of
the dimethylaluminum unit is found in the usual four-
coordinate tetrahedral coordination geometry. How-
ever, the aluminum atom, Al(1), is clearly five-coordi-
nate. Atoms N(8), Al(1), C(17), and C(18) constitute a
basal plane, while the coordination sphere of Al(1) is
completed by N(1) and S(11) residing in the axial
positions on either side of the N-Al-C2 basal plane.
As the S(11)-Al(1)-N(1) bond angle is 156.5(2)° and the
sum of the bond angles surrounding the Al atom on the
basal plane is 360.0°, the coordination environment
about Al(1) may be described as distorted trigonal
bipyramidal (tbp). The distortion is mainly caused by
the rigid geometry of the 2-acetylpyridine thiosemicar-
bazone ligand (bite angle, i.e., N(1)-Al(1)-N(8) 76.4-
(2)°; N(8)-Al(1)-S(11) 80.1(2)°), which prevents them
(16) (a) Rettig, S. T.; Storr, A.; Trotter, J . Can. J . Chem. 1976, 54,
1278. (b) Rettig, S. T.; Storr, A.; Trotter, J . Can. J . Chem. 1975, 53,
58. (c) Rettig, S. T.; Storr, A.; Trotter, J . Can. J . Chem. 1975, 53, 753.
(d) Lee, B.; Pennington, W. T.; Robinson, G. H. Organometallics 1990,
9, 1709.
(17) Shakir, R., Zaworotko, M. J .; Atwood, J . L. J . Organomet. Chem.
1979, 171, 9.
(18) Robinson, G. H.; Zhang, H.; Atwood, J . L. Organometallics 1987,
6, 887.
(19) Rose, D. J .; Chang, Y. D.; Chen, Q.; Kettler, P. B.; Zubieta, J .
Inorg. Chem. 1995, 34, 3973.
(20) Power, M. B.; Ziller, J . W.; Barron, A. R. Organometallics 1992,
11, 2783.
(21) Boardman, A.; J iffs, S. E.; Small, R. W. H.; Worrall, I. J . Inorg.
Chem. Acta 1984, 83, L39.
(22) Trepanier, S.; Wang, S. Organometallics 1996, 15, 760.

Organoaluminum and -gallium Complexes
Organometallics, Vol. 16, No. 10, 1997 2115
distances in 8 is primarily the result of ring strain due
to the endocyclic bond angle of 70.3(1)°.
uents on these ligands should allow tuning of their steric
bulk and, as a result, the derivative of the product
compounds. These ligands also display complicated
bonding modes which require further investigation in
order to be understood.
Su m m a r y
The ten new complexes described here significantly
expand upon the few examples of well-characterized
aluminum and gallium complexes of N-heterocyclic
carboxaldehyde thiosemicarbazones. A combination of
X-ray crystallographic and spectroscopic studies con-
firms the nature of these compounds. The X-ray
crystallographic study of (Me2Al)[NC5H4C(CH3)NNC(S)-
NC3H7](AlMe2) (3), described above, provides the first
structural data for the dinuclear aluminum nature with
a five-coordinate AlN2SC2 and a four-coordinate AlN2C2
environment. The terdentate acetylpyridine thiosemi-
carbazones, which have a thiol group, are valuable for
the synthesis of new polynuclear alkylaluminum and
-gallium complexes with different coordination environ-
ments. In addition, modification of the organic substit-
Ack n ow led gm en t. We appreciate the financial sup-
port of the Basic Research Center Program, Ministry
of Education of Korea, 1993. This research was also
supported under the 1995 university professor exchange
program by the Korea Research Foundation.
Su p p or tin g In for m a tion Ava ila ble: Text describing the
X-ray structure determination, tables of structure determina-
tion details, bond distances and angles, atomic coordinates,
and thermal parameters, and ORTEP diagrams for compounds
3 and 8 (34 pages). Ordering information is given on any
current masthead page.
OM960778M