Peng, S.-M.Insertion reactions of isocyanates, isothiocyanates, and carbon bisulfide into Mg-C bonds of polynuclear aluminum-magnesium compounds: Synthesis, characterization, and crystal structures

Article abstract of DOI:10.1021/om9705057

A number of insertion products, viz., Me₂Al(μ-i-Pr₂N)₂Mg[(t-Bu)NC(CH ₃)S] (1), Me₂Al(μ-i-Pr₂N)₂Mg[(Ph)NC(CH₃)S)] (2), Me₂Al(μ-Et₂N)₂Mg[(t-Bu)NC(CH₃)S] (3), Me₂Al(μ-Et₂N)₂Mg-[(Ph)NC(CH₃)S] (4), {Me₂Al(μM-Et₂N)₂Mg[(Ph)NC(CH ₃)O]}₂ (5), and Me₂Al(μ-i-Pr₂N)₂Mg[SC-(CH₃)S] (6) have been synthesized using polynuclear aluminum-magnesium compounds and various heteroannulenes such as isothiocyanates, isocyanates, and carbon disulfide. All the new compounds were characterized by ¹H and ¹³C NMR, IR, and elemental analysis. The structures of two of the above compounds, 1 and 5, have been determined by single-crystal X-ray diffraction technique.

Full text of DOI:10.1021/om9705057

4980
Organometallics 1997, 16, 4980-4984
Peng, S.-M.In ser tion Rea ction s of Isocya n a tes, Isoth iocya n a tes, a n d
Ca r bon Disu lfid e in to Mg-C Bon d s of P olyn u clea r
Alu m in u m -Ma gn esiu m Com p ou n d s: Syn th esis,
Ch a r a cter iza tion , a n d Cr ysta l Str u ctu r es
Chung-Cheng Chang,*,† J in-Huey Chen,† Bhamidi Srinivas,† Michael Y. Chiang,†
Gene-Hsiang Lee,‡ and Shie-Ming Peng‡
Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan, ROC, and
Department of Chemistry, National Taiwan University, Taipei, Taiwan, ROC
Received J une 13, 1997X
A number of insertion products, viz., Me2Al(µ-i-Pr2N)2Mg[(t-Bu)NC(CH3)S] (1), Me2Al(µ-
i-Pr2N)2Mg[(Ph)NC(CH3)S)] (2), Me2Al(µ-Et2N)2Mg[(t-Bu)NC(CH3)S] (3), Me2Al(µ-Et2N)2Mg-
[(Ph)NC(CH3)S] (4), {Me2Al(µ-Et2N)2Mg[(Ph)NC(CH3)O]}2 (5), and Me2Al(µ-i-Pr2N)2Mg[SC-
(CH3)S] (6) have been synthesized using polynuclear aluminum-magnesium compounds and
various heteroannulenes such as isothiocyanates, isocyanates, and carbon disulfide. All the
1
new compounds were characterized by H and 13C NMR, IR, and elemental analysis. The
structures of two of the above compounds, 1 and 5, have been determined by single-crystal
X-ray diffraction technique.
In tr od u ction
insertion of carbodiimides {R′CN(R)NR′} into the Mg-C
bond of polynuclear aluminum-magnesium compounds
represents a rare σ-σ bond formation between the
nitrogen atoms of the carbodiimide and the Mg atom.7
In this paper, we report the synthesis, characterization,
and crystal structures of the products obtained in the
insertion reactions of isocyanates, isothiocyanates, and
carbon disulfide into Mg-C bonds of dimeric and
tetrameric aluminum-magnesium compounds.
The insertion reactions of carbon dioxide1 and its
isoelectronic analogues, such as isocyanates,2 isothio-
cyanates,3 and carbon disulfide,4 into M-X (X ) C, N)
bonds have been studied extensively. Carbon disulfide
has extensive utility in both organic and organometallic
chemistry.5 Recently, we reported the insertion reac-
tions of isothiocyanates and carbodiimides into Mg-X
(X ) C, N) bonds of organomagnesium reagents.6 The
Exp er im en ta l Section
† National Sun Yat-Sen University.
‡ National Taiwan University.
All experiments were carried out in a N2-flushed glovebag,
dry-box, or in vacuo using standard Schlenk techniques.8 All
solvents were distilled and degassed prior to use. tert-Butyl
isothiocyanate, phenyl isothiocyanate, phenyl isocyanate, and
carbon disulfide were purchased from Aldrich and were used
as received. 1H, 13C, and 27Al NMR spectra were measured
on a Varian VXR-300 spectrometer. Chemical shifts are
referred to either SiMe4 (1H) or C6D6 (1H, δ 7.15; 13C {1H}, δ
X Abstract published in Advance ACS Abstracts, October 1, 1997.
(1) For a number of review articles on CO2 activation, see: (a)
Leitner, W. Coord. Chem. Rev. 1996, 153, 257. (b) Leitner, W. Angew.
Chem., Int. Ed. Engl. 1995, 34, 2207. (c) Gibson, D. H. Chem. Rev.
1996, 96, 2063. (d) Palmer, D. A.; Eldik, R. V. Chem. Rev. 1983, 83,
651. (e) Behr, A. Angew. Chem., Int. Ed. Engl. 1988, 27, 661. (f)
Braunstein, P.; Matt, D.; Nobel, D. Chem. Rev. 1988, 88, 747. (g)
Kolomnikov, I. S.; Stepovska, G.; Tyrlik, S.; Vol’pin, S. J . Gen. Chem.,
USSR (Engl. Transl.) 1974, 44, 1710. (h) Darensbourg, D. J .; Ku-
daroski, R. A. Adv. Organomet. Chem. 1983, 22, 129.
(2) Forster, G. D.; Hogarth, G. J . Chem. Soc., Dalton Trans. 1993,
2539. Paul, F.; Fischer, J .; Ochsenbein, P.; Osborn, J . A. Angew. Chem.,
Int. Ed. Engl. 1993, 32, 1638. Abe, H.; Inoue, S. J . Chem. Soc., Chem.
Commun. 1994, 1197. J olly, M.; Mitchell, J . P.; Gibson, V. C. J . Chem.
Soc., Dalton Trans. 1992, 1329. Legzdins, P.; Phillips, E. C.; Rettig, S.
J .; Trotter, J .; Veltheer, J . E.; Yee, V. C. Organometallics 1992, 11,
3104 and a number of references cited therein.
(3) Barker, J .; Kilner, M. Coord. Chem. Rev. 1994, 133, 219. Uhl,
W.; Schu¨tz, U.; Hiller, W.; Heckel, M. Chem. Ber. 1994, 127, 1587.
Hogarth, G.; Skordalakis, E. J . Organomet. Chem. 1993, 458, C8.
Adams, R. D.; Chen, L.; Wu, W. Organometallics 1993, 12, 2404.
(4) Darensbourg, D. J .; Wiegreffe, H. P.; Reibenspies, J . H. Orga-
nometallics 1991, 10, 6. Mason, M. G.; Swepston, P. N.; Ibers, J . A.
Inorg. Chem. 1983, 22, 411. Yih, K. H.; Chen, S. C.; Lin, Y. C.; Lee, G.
H.; Wang, Y. J . Organomet. Chem. 1995, 494, 149. Torres, M. R.;
Perales, A.; Ros, J . Organometallics 1988, 7, 1223. Petz, W.; Weller,
F. J . Chem. Soc., Chem. Commun. 1995, 1049. Leoni, P.; Pasquali,
M.; Peiri, G.; Albenati, A.; Progosin, P. S.; Ru¨egger, H. Organometallics
1995, 14, 3143. Gibson, V. C.; Redshaw, C.; Clegg, W.; Elsegood, M.
R. J . J . Chem. Soc., Chem. Commun. 1994, 2635. Mealli, C.; Hoffmann,
R.; Stockis, A. Inorg. Chem. 1984, 23, 56. Legzdins, P.; Rettig, R. J .;
Ross, K. J . Organometallics 1994, 13, 569. Cadeirno, V.; Gamasa, M.
P.; Lastra, E. J . Organomet. Chem. 1996, 510, 207.
128.00), while 27Al NMR spectra were referred to [Al(H2O)6]3+
.
Mass spectral data were obtained on a VG-7025 GC/MS/MS
spectrometer, IR spectra were recorded of Nujol mulls between
KBr disks on a Bio-Rad FTS-40 FT-IR spectrometer. Elemen-
tal analyses (C, H, N) were performed at the Analytische
Laboratorien, Lindlar, Germany. Deviations in the results
from calculated values are attributed to the extremely air-
sensitive and hygroscopic nature and limited thermal stabili-
ties of these compounds.
The starting materials [Me2Al(µ-i-Pr2N)2Mg(µ-Me)]4 (A) and
[Me2Al(µ-Et2N)2Mg(µ-Me)]2 (B) were prepared as described
elsewhere.9
Syn th esis of Me2Al(µ-i-P r 2N)2Mg[(t-Bu )NC(CH3)S] (1)
a n d Me2Al(µ-i-P r 2N)2Mg[(P h )NC(CH3)S)] (2). To a solution
of A (1.20 g, 4 mmol) in pentane (40 mL) was added 0.5 g, 4
mmol of tert-butyl isothiocyanate (t-BuNCS) in pentane (20
mL). The reaction mixture was stirred for 2 h at room
(6) Srinivas, B.; Chang, C. C.; Chen, C. H.; Chiang, M. Y.; Chen, I.
T.; Lee, G. H.; Wang, Y. J . Chem. Soc., Dalton Trans. 1997, 957.
(7) Li, M. D.; Chang, C. C.; Wang, Y.; Lee, G. H. Organometallics
1996, 15, 2571.
(8) Shriver, D. F. The manipulation of air-sensitive compounds;
Wiley Interscience, 2nd ed.; New York, 1986.
(5) Pandey, K. K. Coord. Chem. Rev. 1995, 140, 37. Yaneff, P. V.
Coord. Chem. Rev. 1977, 23, 183. Gattow, G.; Behrendt, Topics in
Sulfur Chemistry; Georg Thieme Verlag: Stuttgart, 1977; Vol. 2. Li,
J .; Hoffmann, R.; Mealli, C.; Silvesre, J . Organometallics 1989, 8, 1921.
Linford, L.; Raubenheimer, H. G. Comments Inorg. Chem. 1991, 12,
113.
(9) Her, T. Y.; Chang, C. C.; Liu, L. K. Inorg. Chem. 1992, 31, 2291.
S0276-7333(97)00505-0 CCC: $14.00 © 1997 American Chemical Society

Mg-C Bonds of Polynuclear Al-Mg Compounds
Organometallics, Vol. 16, No. 23, 1997 4981
Ta ble 1. Cr ysta l a n d In ten sity Collection Da ta for
Com p lexes 1 a n d 5
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p ou n d s 1 a n d 5
1
5
Me2Al(µ-i-Pr2N)2Mg[(t-Bu)NC(CH3)S] (1)
S(1)-Mg(1)
Al(1)-N(1)
Al(1)-C(7)
Mg(1)-N(1)
Mg(1)-N(3)
N(1)-C(4)
N(2)-C(12)
N(3)-C(19)
2.429(2)
1.977(6)
1.989(8)
2.132(6)
2.150(4)
1.500(9)
1.508(9)
1.292(6)
S(1)-C(19)
Al(1)-N(2)
Al(1)-C(8)
Mg(1)-N(2)
N(1)-C(1)
N(2)-C(9)
N(3)-C(15)
1.737(6)
1.949(6)
1.990(7)
2.148(6)
1.481(9)
1.504(8)
1.505(6)
formula
molar mass/g
crystal system
diffractometer
space group
a, Å
C20H46N3SAlMg
411.95
C36H68N6O2Al2Mg2
719.54
monoclinic
Nonius
P21/n (No. 14)
11.152(3)
13.727(5)
14.599(6)
100.53(3)
2197.2(13)
2
monoclinic
Rigaku AFC6S
P21/n (No. 14)
8.301(2)
14.300(4)
21.916(5)
92.67(2)
2598.6(9)
4
912.0
1.053
1.91
47.1
b, Å
c, Å
â, deg
Mg(1)-S(1)-C(19)
N(1)-Al(1)-C(7)
N(2)-Al(1)-C(7)
S(1)-Mg(1)-N(2)
N(1)-Mg(1)-N(2)
N(2)-Mg(1)-N(3)
Al(1)-N(1)-C(1)
Mg(1)-N(1)-C(1)
C(1)-N(1)-C(4)
Al(1)-N(2)-C(9)
Mg(1)-N(2)-C(9)
Mg(1)-N(3)-C(19)
N(3)-C(15)-C(16)
N(3)-C(15)-C(18)
S(1)-C(19)-N(3)
N(3)-C(19)-C(20)
76.5(2) N(1)-Al(1)-N(2)
109.4(3) N(1)-Al(1)-C(8)
110.2(3) N(2)-Al(1)-C(8)
127.7(2) S(1)-Mg(1)-N(1)
85.7(2) S(1)-Mg(1)-N(3)
126.1(2) N(1)-Mg(1)-N(3)
114.8(5) Al(1)-N(1)-Mg(1)
106.4(4) Al(1)-N(1)-C(4)
117.4(6) Al(1)-N(2)-Mg(1)
113.2(5) Al(1)-N(2)-C(12)
106.1(4) Mg(1)-N(2)-C(12) 111.2(5)
96.9(3) Mg(1)-N(3)-C(15) 139.5(4)
105.1(5) C(15)-N(3)-C(19)
111.2(6) N(1)-C(1)-C(3)
117.6(4) S(1)-C(19)-C(20)
129.1(5)
95.7(2)
V, Å3
114.7(3)
115.7(3)
128.9(2)
68.9(1)
126.0(2)
87.9(2)
112.2(4)
114.3(5)
123.6(5)
Z
F(000)
785.0
1.088
1.248
45.0
D
calc, g/cm3
µ, cm-1
2θ (max)
cryst dimens, mm
no. of measd reflctns
no. of unique reflctns
no. of obsd reflctns
no. of variables
Rf, Rw
data collection temp, °C 23
goodness of fit (GOF)
radiation
0.33 × 0.35 × 0.40 0.40 × 0.50 × 0.60
4381
4066
2851
2851
1988 [(I > 3.0σ(I)] 1577 [(I > 2.0σ(I)]
235
0.058; 0.057
217
0.064; 0.074
25
1.64
Mo KR
123.6(5)
116.0(7)
113.2(4)
3.04
Mo KR
(graphite monoch)
intensity decay (%)
{Me2Al(µ-Et2N)2Mg[(Ph)NC(CH3)O]}2 (5)
3
5
Al-Mg
2.865(3)
1.922(8)
1.925(6)
1.967(9)
1.972(8)
2.260(6)
1.978(5)
2.134(6)
2.151(7)
Mg-N(3)
O-Mg
O-C(11)
N(1)-C(3)
N(1)-C(5)
N(2)-C(7)
N(2)-C(9)
N(3)-C(11)
N(3)-C(13)
2.181(6)
Al-N(1)
Al-N(2)
Al-C(1)
Al-C(2)
Mg-O
Mg-O
Mg-N(1)
Mg-N(2)
1.978(5)
1.320(8)
1.494(10)
1.480(11)
1.484(10)
1.490(11)
1.264(10)
1.421(9)
temperature, and the reaction mixture then was centrifuged.
Colorless crystals of 1 (1.4 g, 75%) were obtained upon cooling
for 8 h. A procedure similar to that used for 1 was adopted
for the preparation of 2 except for using phenyl isothiocyanate
(PhNCS) in place of t-BuNCS. Compound 1. mp: 104 °C (dec).
1H NMR (C6D6): δ -0.237 (s, 6H, Al(CH3)), 1.08 (s, 9H,
C(CH3)3), 1.31 (d, 24H, N(CH3)2), 2.28 (s, 3H, t-BuNC(CH3)S),
3.66 (br, 4H, NCH(CH3)2. 13C NMR (C6D6): δ -4.23 (br, (Al-
(CH3)2), 30.12 (t-BuNC(CH3)S), 27.05 (NCH(CH3)2, 30.97
(C(CH3)3), 45.30 (NCH(CH3)2), 56.05 (CCH3)3), 196.42 (t-
BuNC(CH3)S)). 27Al-NMR (C6D6): δ 140 (br). Mass spectrum
(EI, 70 eV): 10 most intense m/e peaks 131, 41, 42, 57, 75, 58,
76, 59, 56, 55. IR (Nujol, cm-1): 2917 (s), 2842 (s), 2718 (sh),
1620 (w), 1518 (m), 1470 (s), 1384 (s), 1176 (m), 1029 (w), 910
Mg-Al-N(1)
Mg-Al-N(2)
Mg-Al-C(1)
Mg-Al-C(2)
N(1)-Al-N(2)
N(1)-Al-C(1)
N(1)-Al-C(2)
N(2)-Al-C(1)
N(2)-Al-C(2)
C(1)-Al-C(2)
Al-Mg-O
48.16(18) Mg-O-Mg
48.64(21) Mg-O-C(11)
110.6(3)
116.0(4)
94.6(3)
112.1(4)
110.9(4)
110.6(3)
116.0(4)
111.6(4)
103.61(22)
89.0(4)
153.9(5)
89.7(3)
Mg-O-C(11)
Al-N(1)-Mg
Al-N(1)-C(3)
Al-N(1)-C(5)
Mg-N(1)-C(3)
Mg-N(1)-C(5)
C(3)-N(1)-C(5)
Al-N(2)-Mg
113.8(5)
116.1(5)
108.5(4)
116.4(5)
110.7(7)
89.2(3)
114.7(5)
116.1(5)
111.9(5)
114.2(5)
109.5(6)
94.1(4)
(w), 969 (m), 754 (m), 662 (m), 609 (m). Anal. Calcd for C20H46
N3SMgAl: C, 58.30; H, 11.28; N, 10.20. Found: C, 58.09; H,
11.11; N, 10.30.
-
150.37(17) Al-N(2)-C(7)
128.85(18) Al-N(2)-C(9)
42.12(20) Mg-N(2)-C(7)
42.20(17) Mg-N(2)-C(9)
100.76(18) C(7)-N(2)-C(9)
76.39(20) Mg-N(3)-C(11)
Compound 2. Yield: 65%. mp: 156 °C (dec). 1H NMR
(C6D6): δ -0.47 (s, 6H, Al(CH3)), 1.26 (d,d, 24H, NCH(CH3)2),
2.04 (s, 3H, PhNC(CH3)S), 3.48 (sep, 4H, NCH(CH3)2), 6.93,
6.70, 7.09 (m, 5H, C6H5). 13C NMR (C6D6): δ -4.16 (br, (Al-
(CH3)2), 26.45 (NCH(CH3)2, 34.45 (PhNC(CH3)S), 47.89 (NCH-
(CH3)2), 123.87 (o-C, C6H5), 125.53 (ipso-C, C6H5), 129.32 (m-
C, C6H5), 200.15 (PhNC(CH3)S). 27Al NMR (C6D6): δ 160 (br).
Mass spectrum (EI, 70 eV) 10 most intense m/e peaks at 44,
77, 118, 135, 86, 58, 43, 51, 119, 42. IR (Nujol, cm-1): 2049
(w), 1590 (m), 1466 (s), 1377 (m), 1277 (w), 1165 (m), 1072
(w), 1018 (w), 964 (w), 910 (w), 841 (sh), 749 (m), 690 (s). Anal.
Calcd for C22H42N3SMgAl: C, 61.11; H, 9.72; N, 9.72. Found:
C, 58.09; H, 11.11; N, 10.30.
Syn th esis of Me2Al(µ-Et2N)2Mg[(t-Bu )NC(CH3)S] (3)
a n d Me2Al(µ-Et2N)2Mg[(P h )NC(CH3)S] (4). To a solution
of B (0.96 g, 4 mmol) in pentane (40 mL) was added a solution
of t-BuNCS (0.5 g, 4 mmol) in pentane (20 mL), and the
reaction mixture was stirred for 8 h. Compound 3 (0.87 g,
60%) was obtained as white solid upon cooling the reaction
mixture for 8 h. A similar procedure was employed for the
synthesis of 4 in diethyl ether solvent. Compound 3. mp: 210
°C (dec). 1H NMR (C6D6): δ -0.43 (s, 6H, Al(CH3)), 0.82 (s,
9H, C(CH3)3), 0.99 (t, 12H, NCH2CH3), 2.25 (s, 3H, t-BuNC-
(CH3)S), 2.92 (q, 8H, NCH2CH3). 13C NMR (C6D6): δ -9.70
(br, Al(CH3)2), 13.51 (NCH2CH3), 29.52 (t-BuNC(CH3)S), 40.08
(NCH2CH3), 55.29 (C(CH3)3), 197.38 (t-BuNC(CH3)S). 27Al
NMR (C6D6): δ 160 (br). Mass spectrum (EI, 70 eV): 10 most
Al-Mg-O
Al-Mg-N(1)
Al-Mg-N(2)
Al-Mg-N(3)
O-Mg-O
O-Mg-N(1)
O-Mg-N(2)
O-Mg-N(3)
N(1)-Mg-N(2)
N(1)-Mg-N(3) 104.70(24) O-C(11)-C(12)
N(2)-Mg-N(3) 105.56(25) N(3)-C(11)-C(12) 125.3(7)
117.1(3)
Mg-N(3)-C(13)
144.3(5)
156.89(24) C(11)-N(3)-C(13) 121.0(6)
129.79(23) N(1)-C(3)-C(4)
82.5(3) O-C(11)-N(3)
116.0(7)
117.2(6)
117.4(6)
intense m/e peaks at 57, 72, 58, 42, 114, 41, 44, 243, 128, 73.
IR (Nujol, cm-1): 1513 (m), 1459 (m), 1376 (m), 1191 (w), 1131
(m), 1039 (w), 991 (w), 845 (w), 781 (w), 670 (m). Anal. Calcd
for C16H38N3SMgAl: C, 53.93; H, 10.67; N, 11.80. Found: C,
53.24; H, 10.18; N, 11.26.
Compound 4. Yield: 46%. mp: 121 °C. 1H NMR (C6D6):
δ -0.43 (s, 6H, Al(CH3)2), 1.04 (t, 12H, NCH2CH3), 2.13 (s, 3H,
PhNC(CH3)S); 2.90 (m, 8H, NCH2CH3), 6.74, 6.92, 7.05 (m, 5H,
C6H5). 13C NMR (C6D6): δ -9.77 (br, Al(CH3)2), 14.08
(NCH2CH3), 27.67 (PhNC(CH3)S), 41.00 (NCH2CH3), 122.99
(o-C, C6H5), 123.45 (ipso-C, C6H5), 129.35 (m-C, C6H5). 27Al
NMR (C6D6): δ 160 (br). Mass spectrum (EI, 70 ev): 10 most
intense m/e peaks at 58, 360, 245, 231, 118, 174, 303, 77, 289,
375. IR (Nujol, cm-1): 2055 (w), 1593 (m), 1456 (s), 1370 (m),
1280 (w), 1172 (m), 1055 (w), 970 (w), 908 (w), 825 (s), 790 (s),

4982 Organometallics, Vol. 16, No. 23, 1997
Chang et al.
Sch em e 1
Sch em e 2
688 (m). Anal. Calcd for C18H34N3SMgAl: C, 57.44; H, 9.04;
N, 11.17. Found: C, 58.09; H, 11.11; N, 10.30.
The solvent was removed in vacuo, and the crude product was
recrystallized from pentane to yield 6. Yield: 0.45 g; 30%.
mp: 65 °C (dec). 1H NMR (C6D6): δ -0.25 (s, 6H, Al(CH3)2),
1.22 (d, 24H, NCH(CH3)2), 2.77 (s, 3H, SC(CH3)S), 3.46 (sep,
NCH(CH3)2). 13C NMR (C6D6): δ -3.59 (br, Al(CH3)2), 26.56
(NCH(CH3)2, 44.55 (SC(CH3)S), 48.02 (NCH(CH3)2), 264.39
(SC(CH3)S). 27Al NMR (C6D6): δ 160 (br). Mass spectrum (EI,
70 eV): 10 most intense m/e peaks at 44, 86, 200, 43, 42, 51,
57, 214, 115, 58. IR (Nujol, cm-1): 2922 (s), 2847 (s), 1453
(s), 1378 (s), 1260 (w), 1142 (m), 1017 (w), 969 (w), 958 (w),
872 (w), 797 (w). Anal. Calcd for C16H37N2S2MgAl: C, 51.61;
H, 9.95; N, 7.53. Found: C, 49.31; H, 9.22; N, 6.96.
St r u ct u r e Det er m in a t ion . Suitable single crystals of
complexes 1 and 5 were sealed in glass capillaries for X-ray
diffraction study. Preliminary examination and intensity data
collection were carried out with either a Rigaku AFC6S
diffractometer (for 1) or an Enraf-Nonius CAD-4 automatic
diffractometer (for 5) using graphite-monochromatized Mo KR
(λ ) 0.710 69 Å) radiation. Intensity data were collected using
the θ-2θ scan mode and corrected for absorption and decay.
The structures were solved by SIR9210 (for 1) or by MULTAN11
(for 5) and refined with full-matrix least squares on F. In the
final cycles, all non-hydrogen atoms were refined anisotropi-
Syn th esis of {Me2Al(µ-Et2N)2Mg[(P h )NC(CH3)O]}2 (5).
To a solution of B, (0.96 g, 4 mmol) in diethyl ether (40 mL)
was added a solution of PhNCO (0.68 g, 4 mmol) in diethyl
ether (20 mL). The solution was stirred for 8 h and centri-
fuged. Cooling the resultant supernatant solution yielded
colorless crystals of 5 (0.91 g, 56%). Compound 5. mp: 153
°C. 1H NMR (C6D6): δ -0.41 (s, 6H, Al(CH3)2), 1.00 (t, 12H,
NCH2CH3), 1.72 (s, 3H, PhNC(CH3)O), 2.934 (m, 8H, NCH2-
CH3), 6.91, 6.97, 7.14 (m, 5H, C6H5). 13C NMR (C6D6): δ -9.49
(br, Al(CH3)2), 13.41 (NCH2CH3), 19.03 (PhNC(CH3)O), 40.28
(NCH2CH3), 124.20 (o-C, C6H5), 125.31 (ipso-C, C6H5), 129.44
(m-C, C6H5). 27Al NMR (C6D6): δ 160 (br). Mass spectrum (EI,
70 eV): 10 most intense m/e peaks at 229, 344, 287, 118, 215,
57, 58, 158, 114, 176. IR (Nujol, cm-1): 2923 (s), 2853 (s), 2728
(sh), 2664 (sh), 1555 (w), 1459 (s), 1377 (s), 1303 (sh), 1249
(w), 1131 (w), 1023 (w), 958 (w), 721 (m), 662 (w), 593 (w).
Anal. Calcd for C36H68N6O2Mg2Al2: C, 60.10; H, 9.47; N, 11.70.
Found: C, 58.58; H, 9.10; N, 11.31.
Syn th esis of Me2Al(µ-i-P r 2N)2Mg[SC(CH3)S] (6). To a
solution of A (1.20 g, 4 mmol) in pentane (40 mL) was added
CS2 in excess (5 mL). The reaction took place immediately.

Mg-C Bonds of Polynuclear Al-Mg Compounds
Organometallics, Vol. 16, No. 23, 1997 4983
cally and all hydrogen atoms were fixed at idealized positions.
All calculations were carried out with a SGI R4000 computer
using the teXsan program package12 (for 1) or a Microvax 3600
computer using the NRCVAX program package13 (for 5).
A
summary of the data collection and structure solution is given
in Table 1; selected bond lengths and angles are given in Table
2.
Resu lts a n d Discu ssion
Syn th esis, Ch a r a cter iza tion , a n d Sp ectr a l Da ta .
Compounds 1-6 were obtained by the straightforward
reaction between the reagents tert-butyl, and phenyl
isothiocyanate, phenyl isocyanate, and carbon disulfide
with the respective polynuclear aluminum-magnesium
precursor compounds, A and B. Except in the case of
the reaction of B with phenyl isocyanate, in which case
a tetranuclear compound was obtained, all other reac-
tions yielded only dinuclear insertion products (see
Schemes 1 and 2). In the case of 1, a distinct change in
the NMR pattern of the product compared to that of the
starting A was noticed after the insertion of tert-butyl
isothiocyanate. The Mg-CH3 signal had shifted down-
field to δ 2.285 ppm, indicating the migration of the
methyl group from Mg to the carbon atom of the NCS
unit. A change in CH3 chemical shift of similar mag-
nitude also was noticed in the case of 2-6. The 13C
NMR resonance associated with the carbon of the
inserted CS2 group was observed at δ 264 ppm for 6.
In the IR spectra for 1-4, there was no band at ca.
2150 cm-1 attributable to asymmetric stretching fre-
quency of sNdCdS and the bands that were observed
are similar to the characteristic bands observed for
N-methylthioacetamide (1550, 1200, and 720 cm-1).14
The IR spectrum of 5 displayed a carbonyl stretch at
1555 cm-1 for the PhNCO group. The CS2 insertion
product 6 has been formulated as having η2-S2CR
ligands on the basis of its Nujol mull IR spectrum, which
showed two bands at 1142 and 1017 cm-1, which are
assignable to the symmetric and asymmetric stretching
frequencies of the CS2-containing fragments. These
values are comparable to those exhibited by closely
related CS2 insertion products, Cp*W(NO)(η2-S2CN-
F igu r e 1. ORTEP view of the complex Me2Al(µ-i-Pr2N)2-
Mg[(t-Bu)NC(CH3)S] (1). Thermal ellipsoids are drawn at
50% probability level.
F igu r e 2. ORTEP view of the complex {Me2Al(µ-Et2N)2-
Mg[(Ph)NC(CH3)O]}2 (5). Thermal ellipsoids are drawn at
50% probability level.
HCMe3)(OCMe3)15 and Cp*W(NO)(η2-S2CPh)(Ph).16
A
Mg, and the amide nitrogen atoms of the two (i-Pr2)N
ligands while the other is formed by a Mg atom and
carbon, sulfur, and nitrogen atoms of the methyl-
migrated tert-butyl isothiocyanate moiety. These two
rings are connected through the magnesium atom.
Each of the rings is nearly coplanar and approximately
perpendicular to each other. The observed C(19)-N(3)
and C(19)-S(1) bond distances of 1.292 (6) and 1.737
(6) Å fall between single- and double- bond values.18,19
Compound 5 consists of an interlinked tricyclic struc-
ture similar to that of its parent compound as shown in
Figure 2. Selected bond distances and angles are listed
in Table 2. The molecule possesses crystallographic
inversion center symmetry at the center of the Mg2O2
ring.
number of trithiocarbonato complexes contain bands
corresponding to the ν(CdS) and ν(CsS) modes in the
990-1054 and 850-885 cm-1 regions.17
Descr ip tion of Str u ctu r es. Compound 1 possesses
an interlinked bicyclic structure as shown in Figure 1.
Selected bond lengths and angles are listed in Table 2.
As seen in Figure 1, one of the rings is formed by Al,
(10) SIR92: Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, M.;
Giacovazzo, C.; Guagliardi, A.; Polidori, G. J . Appl. Crystallogr. 1994,
27, 1045.
(11) Main, P.; Fiske, S. J .; Hill, S. E.; Lessinger, L.; Germain, G.;
Declercq, J .-P.; Woolfson, M. M. MULTAN 80, A system of computer
programs for the automatic solution of crystal structures from X-ray
diffraction data, University of York and Louvain, 1980.
(12) teXsan: Crystal Structure Analysis Package; Molecular Struc-
ture Corp., College Station, TX, 1985, 1992.
(13) Gabe, E. J .; Lee, F. L.; Le Page, Y. In Crystallographic
Computing 3: Data Collection, Structure Determination, Proteins, and
Databases; Sheldrick, G. M., Krueger, C., Goddard, R., Eds.; Clarendon
Press: Oxford, U.K., 1985; p 167.
(14) J enson, K. A.; Nielsen, P. H. Acta Chem. Scand. 1966, 20, 597.
(15) Legzdins, P.; Rettig, S. J .; Ross, K. J . Organometallics 1994,
13, 569.
The two symmetrically related terminal rings are
formed by Al, Mg, and amide nitrogen atoms of the
(Et2N) groups. The structural features of the rings are
comparable to those of the terminal rings in the parent
compound B.10 The middle ring is defined by two sets
(16) Brouwer, E. B.; Legzdins, P.; Retting, S. J .; Ross, K. J .
Organometallics 1993, 12, 4234.
(17) Vicente, J .; Chicote, M. T.; Gonza`lez-Herrero, P.; J ones, P. G.
J . Chem. Soc., Chem. Commun. 1995, 745 and references cited therein.
(18) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J . Chem. Soc., Perkin Trans. 2 1987, S1.
(19) Ha¨felinger, G. Chem. Ber. 1970, 103, 2920.

4984 Organometallics, Vol. 16, No. 23, 1997
Chang et al.
of symmetrically related Mg and oxygen atoms and is
planar with alternating Mg-O distances of 1.978(5) and
2.260(6) Å. The O-Mg-O and Mg-O-Mg angles are
76.39(20) and 103.60(22)°, respectively, and the inter-
metallic Mg-Mg distance is 3.335(5) Å. The Mg-Al
distance in the present compound is comparable to that
in the parent compound, as could be expected. The
observed C-N and C-O bond distances associated with
the sp carbon atom of 1.264(10) and 1.320(8) Å are
commensurate with CdN and CsO, respectively. The
observation of two dissimilar Mg-O distances in the
middle ring reveals that the tetranuclear arrangement
is due largely to both the ability of the ligating oxy group
to interact with the neighboring magnesium center and
the small bite angle of the PhNC(CH3)O ligand species,
59.54(21)°.
Å and larger bite angle of the t-BuNC(CH3)S ligand,
68.9(1)°, preclude such a tetranuclear arrangement. Our
recent report on a magnesium dimer similar to 5, in
which the two magnesium atoms are bridged by the
sulfur atoms of the phenyl isothiocyanate, can serve as
an additional case for comparison.6
Ack n ow led gm en t. Financial assistance from the
National Science Council (NSC), Taiwan, Republic of
China is gratefully acknowledged.
Su p p or tin g In for m a tion Ava ila ble: ORTEP drawings
and tables of crystal data, atomic coordinates, temperature
factors, hydrogen coordinates, and intramolecular bond dis-
tances and angles for 1 and 5 (26 pages). Tables of observed
and calculated structure factors can be obtained from the
authors upon request. Ordering information is given on any
current masthead page.
In the case of 1, since the tert-butyl group is disposed
away from the Mg center, a similar tetranuclear ar-
rangment as in 5 could not be expected. We assume
that the considerably longer Mg-S distance of 2.429(2)
OM9705057