Reaction of ruthenium complexes containing heterocyclic thiazine
/thione ligand
Chao-Wan Chang
a, Ying-Chih Lin
b,*
, Gene-Hsiang Lee
b, Yu Wang
b aDepartment of Chemistry, National Overseas Chinese Student University Preparation School, Linkou, Taipei Hsien 244, Taiwan, ROCbDepartment of Chemistry, National Taiwan University, Section 4, Roosevelt Road, Taipei 106, Taiwan, ROC
Received 16 April 2002; received in revised form 30 April 2002; accepted 25 June 2002
Abstract
Treatment of the ruthenium complex [Ru] //
/C /C(Ph)C( /S)N(Ph)C( /NPh)S/
/(3, [Ru] /Cp(dppe)Ru) containing a heterocyclic
[1,3]-thiazine-4-thione six-membered-ring ligand with various organic halides results in alkylation at the thione sulfur terminus of the ligand to yield [Ru] //
/C /C(Ph)C(SCH2R)N(Ph)C( /NPh)S/
/][X] (4a, R /CN, X /I; 4b, R /Ph, X /Br; 4c, R /CH /CH2, X /
I, 4d, R /p -C6H4CF3, X /Br). Similarly the reaction of 3 with HgCl2 at room temperature affords [Ru] / /
/C /C(Ph)C(SHgCl)N(Ph)C( /NPh)S/
/][Cl] (5). Transformation of 5 to the cationic vinylidene complex {[Ru] /C /
C(Ph)C(O)NHPh}2[Hg2Cl6] (6) readily occurred in the air. The structures of 4c and 6 are determined by single crystal X-ray
diffraction analysis.
# 2002 Published by Elsevier Science B.V.
Keywords: Ruthenium; Thiazine /thione; Alkylation
1. Introduction
Recently we reported that the reaction of isocyanates and isothiocyanates with two ruthenium acetylide com-plexes resulted in sequential additions of the organic substrate to the acetylide ligand to produce novel heterocyclic ligands [1]. Namely, treatment of [Ru] /
C /CPh (1, [Ru] /Cp(dppe)Ru) with a 10-fold excess
of PhNCS afforded the [2/2] cycloaddition product
[Ru] //
/C /C(Ph)C( /NPh)S/
/ (2). If the reaction was
carried out for 7 days at room temperature, the [2/2/2] cycloaddition product [Ru] / /
/C /C(Ph)C( /S)N(Ph)C( /NPh)S/
/ (3) could be isolated [1] in moderate yield. In search for new chemical properties of such ruthenium complexes containing heterocyclic ligand, we performed the electrophilic
addition reaction of 2 to form the
S -alkylation and N -alkylation vinylidene complexes. Subsequent cyclization reactions of these vinylidene complexes induced by deprotonation generates neutral heterocyclopentenyl complexes [2]. We also reported
that the reaction of the ruthenium
dihydrofuranyl complex (C5Me5)(dppp)Ru / /
/C /C(Ph)CH(CN)C(CH3)2O/
/with electrophiles, such as
XCH2R, H and HgCl2, afforded a series of cationic carbene complexes [3]. Formation of these cationic carbene complexes occurs via selective addition of electrophiles to the nucleophilic b-carbon of the five-membered ring. New reactivity of these ruthenium complexes containing heterocyclic ligand toward elec-trophiles intrigues us to explore the reactivity of such complexes. One possible site for the electrophilic addi-tion is the sulfur atom of a thioketone group [4 /6]. Herein, we report the electrophilic addition of organic halides to the six-membered-ring heterocycles of com-plex 3. Addition of electrophiles is found to take place at the thione sulfur terminus to give new cationic six-membered-ring complexes. In the case where HgCl2 is
* Corresponding author. Fax: /886-2-2363-6359
E-mail address: [email protected](Y.-C. Lin).
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used as the electrophile, transformation of the product takes place at room temperature in the presence of excess HgCl2in the air to give a new cationic vinylidene complex. Structure of two relevant complexes is con-firmed by single crystal X-ray diffraction analysis.
2. Results and discussion
2.1. Electrophilic addition of ruthenium six-membered-ring complex
When treated with ICH2CN in CHCl3 at room temperature, the orange /yellow solution of 3 changed
to purple in 5 min. The reaction finished in 1 h yielding the cationic complex [Ru] / /
/C /C(Ph)C(SCH2CN)N(Ph)C( /NPh)S/
/][I] (4a). The
electrophilic addition was found to take place at the thione sulfur terminus of the heterocyclic six-membered ring ligand. Chemical shifts of 3 and 4a in 31P-NMR spectra differs only slightly. The31P-NMR resonance of 3 appears at d 99.27 and the resonance attributed to 4a appears at d 99.33. In the1H-NMR spectrum of 3, the singlet resonance at d 3.68 is assigned to the Cp group and multiplet resonance at d 2.65 /2.30 is assigned to
dppe. For 4a, the1H /Cp resonance shifts to d 4.04 and
the singlet resonance at d 2.84 is assigned to the CH2 group. The FAB mass spectrum of 4a shows a parent peak at m /z /976.1. In the presence of excess NH4PF6,
the counter ion is replaced by PF6
.
Reactions of 3 with other organic halides XCH2R (R /Ph, X /Br; R /CH /CH2, X /I; R /p -C6H4CF3, X /Br) give [Ru] / / /C /C(Ph)C(SCH2R)N(Ph)C( /NPh)S/ /][X] (4b, /Ph, X /Br; 4c, R /CH /CH2, X /I; 4d, R /p -C6H4CF3,
X /Br), respectively, (Scheme 1). The most
character-istic spectroscopic data of these cationic six-membered-ring complexes consist of a singlet Cp resonance at d 4.029/0.03 in
1
H-NMR spectra and a singlet resonance at d 99.09/1.0 in
31
P-NMR spectra. Complexes 4a /d are
purple solids, stable in the air, soluble in CH2Cl2, moderately soluble in methanol and acetone, insoluble in diethyl ether and n -hexane. Reaction of 4a /d with n
-Bu4NOH results in removal of the CH2R groups and gives back complex 3. Disappearance of the13C-NMR data of the thione group in 3 provides useful informa-tion of the reacinforma-tion. The 13C resonance at d 180 was previously assigned to the thione carbon atom in 3. Alkylation at the thione group results in appearance of two13C resonances at d 152.8, 149.0 assigned to carbon atoms of two NCS groups in the six-membered ring. Alkylation at the thione sulfur atom is also confirmed by an X-ray diffraction analysis of 4c described below.
Treatment of 3 with excess HgCl2 under nitrogen resulted in a similar electrophilic-addition reaction at the same site and afforded the cationic complex [Ru] //
/C /C(Ph)C(SHgCl)N(Ph)C( /NPh)S/
/][Cl] (5).
Upon addition of HgCl2, the orange /yellow solution
of 3 also changed to deep-purple immediately. The31 P-NMR resonance of 5 appears at d 100.53 again shifts only slightly from that of 3 indicating that the addition takes place at the six-membered ring ligand. In the1 H-NMR spectrum of 5, the Cp resonance appears at d 3.85. The FAB mass spectrum of 5 shows a parent peak at m /z /1173.1. Like 4a /d, complex 5 is stable in the
air, soluble in CH2Cl2, moderately soluble in methanol and acetone, insoluble in diethyl ether and n -hexane.
If the solution of complex 5 is stored in the presence of HgCl2 in the air for more than 1 h, color of the solution changed from deep purple to purple-red gradually. The reaction finished in 3 h to yield the red cationic vinylidene complex [Ru] /C /
C(Ph)C(O)NHPh]2[Hg2Cl6] (6)[7]. The 31P-NMR reso-nance of 6 appears at d 78.33 significantly shifted from that of 5 at d 100.53. In the1H-NMR spectrum of 6, the Cp resonance at d 5.58 and two multiple resonances of dppe at d 3.23 and 3.03 indicate that the ligand environment around the metal should have changed. In the 13C-NMR spectrum, a highly-deshielded triplet resonance at d 348.7 with JCP /15.4 Hz shows that 6 is
a vinylidene complex and two singlet resonances at d 190.1 and 93.2 are assigned to the C /O and Cp groups
of 6, respectively. Complex 6 is a red solid, stable in the air, moderately soluble in CHCl3, CH2Cl2and acetone and insoluble in ether and hexane. Re-crystallization of 6 from acetone/diethyl ether (1:2) afforded red single
crystals, suitable for X-ray diffraction study. Reaction of 6 with bases such as n -Bu4NOH, DBU, NaNH2and
(C2H5)2NH resulted in removal of the amido group PhNHCO- and afforded the metal acetylide complex 1 (seeScheme 1).
Complex 6 could also be obtained by the reaction of [Ru] //
/C /C(Ph)C( /NPh)S/
/(2) with excess HgCl2 in the
air. Treatment of 2 with excess HgCl2in CH2Cl2caused color change of the solution from yellow to purple-red immediately and afforded 6 with high yield. According to our previous report [2], it could afford a cationic vinylidene intermediate [Ru] /C /C(Ph)C( /
NPh)-SHgCl][Cl] first, and then the intermediate could then be oxidized in the air to give 6. The oxidation reaction is fast and the proposed intermediate is observed by NMR spectra.
2.2. Structure determination of 4c and 6
The molecular structure of 4c is determined by an X-ray diffraction study. AnORTEPdiagram of 4c is shown
inFig. 1, crystal and intensity collection data of 4c are given inTable 1 and selected bond distances and bond angles are listed inTable 2. The final R indices for I /
2s (I ) of R1 /0.0951, wR2 /0.2123 and R indices of all
data of R1 /0.1933, wR2 /0.2584 are a little too high.
These high values are partly due to poor quality of the crystal and a 30% disorder of the CH2CH /CH2group,
the crystal data can only be used as a reference for the structure of 4c. The heterocyclic six-membered ring is essentially planar. The Ru /C1 bond length of 2.029(8)
A˚ is typical of a Ru/C single bond, and the C1 /C2
bond length of 1.499(11) A˚ is obviously longer than a typical double bond. The C3 /N2 bond length of
1.391(11) A˚ is between the C4 /N1 double bond
(1.232(11) A˚ ) and C4/N2 single bond (1.433(11) A˚ ).
The planarity of the six-membered-ring along with these bond distance informations indicates that there should be a conjugation in the cyclic ligand. The C3 /S2 single
bond in 4c is 1.787(8) A˚ , which is comparable with the C1 /S1 single bond (1.744(8) A˚ ).
The red single crystals of 6 were obtained by recrystallization of 6 from acetone /diethyl ether (1:2)
for 2 days. The structure of 6 is determined by a single-crystal X-ray diffraction analysis. AnORTEPdrawing of
6 is shown inFig. 2. The crystal and intensity collection data of 6 are given in Table 1 and selected bond distances and bond angles are given in Table 3. The presence of the vinylidene ligand is clearly indicated by the fact the Ru /C1 bond length of 1.842(3) A˚ is typical
of a Ru /C double bond, and the bond length of C1 /C2
and C2 /C3 of 1.323(4) A˚ and 1.520(4) A˚ are typical of a
Fig. 1. AnORTEPdrawing of 4c with thermal cllipsoid shown at the 30% probability level.
Table 1
Crystal and intensity collection data for [Cp(dppe)R-u C C(Ph)C(SCH2CH CH2)N(Ph)C( NPh)S][PF6] (4c) and [Cp(dppe)Ru C C(Ph)C(O)NHPh]2[Hg2Cl6] (6) Molecular for-mula C57H54F6N2OP3RuS2 (4c) C92H78Cl6Hg2N2O2P2Ru2 (6) Space group P 21/c P/¯1/
Crystal system Monoclinic Triclinic a (A˚ ) 18.7860(2) 12.7619(1) b (A˚ ) 13.6014(2) 12.8464(2) c (A˚ ) 21.15500(10) 13.6499(2) a (8) 90 90.686(1) b (8) 92.1340(10) 94.353(1) g (8) 90 103.499(1) V (A˚3) 5401.69(10) 2168.71(5) Z 4 1 Crystal size (mm) 0.40 0.25 0.03 0.45 0.30 0.30 2u Range (8) 1.08 /25.16 1.50 /26.37 Total number of reflections 9573 8823 Final R indices [I 2s (I )] R1 0.0951, wR2 0.2123 R1 0.0286, wR2 0.0572 R indices (all data) R1 0.1933, wR2 0.2584 R1 0.0389, wR2 0.0620 Table 2
Selected bond distances (A˚ ) and angles (8) of [Cp(dppe) Ru / /C C(Ph)C(SCH2CH CH2)N(Ph)C( NPh)S/ /][I] (4c) Ru P1 2.313(3) Ru P2 2.320(2) Ru C1 2.032(8) C1 C2 1.487(12) C2 C3 1.361(12) C3 N2 1.398(12) C4 N2 1.437(12) S1 C1 1.753(9) S1 C4 1.755(9) S2 C3 1.788(9) S2 C11 1.827(14) C11 C12 1.52(4) C12 C13 1.15(5) P1 Ru P2 83.85(10) Ru C1 C2 132.7(6) Ru C1 S1 114.3(4) C1 C2 C3 123.6(8) C2 C3 N2 127.7(8) N2 C4 S1 122.8(7) C2 C1 S1 113.0(6) C3 S2 C11 102.4(5) S2 C11 C12 109(2) C11 C12 C13 137(4) C1 S1 C4 111.9(4)
carbon /carbon double and single bond, respectively.
The O1 /C3 bond length of 1.208(4) A˚ is that of a C/O
double bond and the bond length of C3 /N1 (1.332(4)
A˚ ) is shorter than that of a C/N single bond. There
should be some delocalization at O1 /C3 and C3 /N1
bonds. Instead of two Cl , the counter anion is Hg2Cl62 , which is formed from two chloride anions with excess HgCl2in CH2Cl2solution. Similar examples were found in other reported literature[8 /10].
2.3. Conclusions
Complex 3 containing a heterocyclic [1,3]-thiazine-4-thione six-membered-ring ligand reacted with alkyl halide RCH2X (X /Br or I; R /CN, CH /CH2, Ph, p
-C6H4CF3) to afford cationic ruthenium com-plexes [Ru] // /C /C(Ph)C(SCH2R)N(Ph)C( /NPh)S/ /][X] (4a, R /CN, X /I; 4b, R /C6H5, X /Br; 4c, R / CH /CH2, X /I, 4d, R /p -C6H4CF3, X /Br). The
reaction of 3 with HgCl2 afforded
[Ru] //
/C /C(Ph)C(SHgCl)N(Ph)C( /NPh)S/
/][Cl] (5),
which was oxidized in the air to give the cationic ruthenium vinylidene complex [Ru] /C /
C(Ph)C(O)NHPh]2[Hg2Cl6] (6).
3. Experimental 3.1. General
All manipulations were performed under nitrogen using vacuum-line, dry box, and standard Schlenk techniques. CH2Cl2was distilled from CaH2and diethyl ether and THF from sodium diphenyketyl. All other solvents and reagents were of reagent grade and were used without further purification. NMR spectra were recorded on Bruker AC-200 and AM-300WB FT-NMR spectrometers at room temperature (unless states other-wise) and are reported in units of d with residual protons in the solvents as an initial standard (CDCl3, d 7.24: acetone-d6, d 2.04). FAB mass spectra were recorded on a JEOL SX-102A spectrometer. Complexes [Ru]C /CPh (1) [11], 2 and 3 [1,2] were prepared
following the methods reported in the literature. Ele-mental analyses and X-ray diffraction studies were carried out at the Regional Center of Analytical Instrument located at the National Taiwan University. 3.1.1. Synthesis of [Ru] // /C /C(Ph)C(SCH2CN)N(Ph)C( /NPh)S/ /][I] (4a) To a 20 ml CH2Cl2 solution of 3 (200.1 mg, 0.214 mmol) ICH2CN (0.047 ml, 0.642 mmol) was added. The solution was stirred for 2 h, then the solvent was reduced to 5 ml. This mixture was slowly added to 60 ml of a vigorously stirred diethyl ether. Purple-red precipitates, thus, formed were filtered and washed with diethyl ether and hexane and dried under vacuum to give the product 4a (171.1 mg, 0.175 mmol) in 82% yield. Spectroscopic data of 4a are as follows: 1H-NMR (CDCl3): d 7.64 /
5.92 (m, 35H, Ph), 4.04 (s, 5H, Cp), 2.84 (s, CH2), 2.92, 2.65 (m, 4H, PCH2CH2P). 31 P-NMR (CDCl3): d 99.33. 13 C-NMR (CDCl3): d 152.8, 149.0 (SC N), 146.3 /120.7 (m, Ph, Ca and Cb), 114.4 (CN), 90.9 (Cp), 30.1 (t, PCH2CH2P, JCP /19.7 Hz), 20.2 (CH2). MS (FAB, m / z ): 976.1 [M /I], 565.0 [M /I /CH2CN /
2PhNCS /CCPh]. Anal. Calc. for C55H46N3P2S2RuI
(1102.98): C, 59.89; H, 4.20; N, 3.81. Found: C, 60.10; H, 4.25; N, 3.63%. Complex [Ru] / / /C /C(Ph)C(SCH2Ph)N(Ph)C( /NPh)S/ /][Br] (4b) (160.3
mg, 0.158 mmol, 74% yield from 200.0 mg of 3),
complex [Ru] / / /C /C(Ph)C(SCH2CH /CH2)N(Ph)C( /NPh)S/ /][I] (4c)
(156.6 mg, 0.161 mmol, 75% yield from 200.2 mg
Fig. 2. AnORTEPdrawing of 6 with thermal cllipsoid shown at the
30% probability level.
Table 3
Selected bond distances (A˚ ) and angles (8) of [Cp(dppe)R-u C C(Ph)C(O)NHPh]2[Hg2Cl6] (6) Ru P1 2.3028(7) Ru C1 1.842(3) Ru P2 2.3114(8) O1 C3 1.208(4) N1 C10 1.417(4) C2 C4 1.475(4) N1 C3 1.332(4) C1 C2 1.323(4) C2 C3 1.520(4) C1 Ru P1 84.94(9) C1 Ru P2 91.70(9) P1 Ru P2 81.86(3) C3 N1 C10 129.2(3) C2 C1 Ru 179.6(2) C1 C2 C3 117.7(3) O1 C3 N1 124.4(3) N1 C3 C2 114.8(3) C1 C2 C4 124.6(3) C4 C2 C3 117.5(3) O1 C3 C2 120.7(3)
of 3), and complex {[Ru] / / /C /C(Ph)C[SCH2(p -C6H4CF3)]N(Ph)C( /NPh)S/ /}[Br]
(4d) (191.1 mg, 0.171 mmol, 80% yield from 199.9 mg of 3) were similarly prepared from BrCH2Ph, ICH2CH /
CH2, and BrCH2(p -C6H4CF3, respectively. Spectro-scopic data of 4b are as follows:1H-NMR (CDCl3): d 7.88 /5.97 (m, 35H, Ph), 4.02 (s, 5H, Cp), 3.33 (s, CH2), 2.93, 2.63 (m, 4H, PCH2CH2P). 31P-NMR (CDCl3): d 99.73.13C-NMR (CDCl3): d 146.4, 144.7 (SC N), 141.3 / 120.6 (m, Ph and Ca, Cb), 90.2 (Cp), 40.7 (CH2), 29.9 (t, PCH2CH2P, JCP /21.9 Hz). MS (FAB, m /z ): 1027.3 [M /Br], 565.1 [M /Br /CH2Ph /2PhNCS /
CCPh]. Anal. Calc. for C60H51N2P2S2BrRu (1107.06): C, 65.09; H, 4.64; N, 2.53. Found: C, 66.02; H, 4.73; N, 2.37%. Spectroscopic data of 4c are as follows: 1 H-NMR (CDCl3): d 7.57 /6.99 (m, 30H, Ph), 5.95 (d, 1H, JHH /7.36 Hz, CH /CHHtrans to H), 5.36 (m, 1H, CH / CH2), 4.01 (s, 5H, Cp), 4.97 (d, 1H, JHH /6.19 Hz, CH /CHHcis to H), 2.76 (d, 2H, JHH /7.01 Hz, CH2), 2.85, 2.65 (m, 4H, PCH2CH2P). 31P-NMR (CDCl3): d 99.37.13C-NMR (CDCl3): d 158.2, 149.7 (SC N), 146.4 (C H /CH2), 144.8 /119.1 (m, Ph and Ca, Cb), 90.2 (Cp), 39.1 (CH2), 29.8 (t, PCH2CH2P, JCP /21.9 Hz). MS (FAB, m /z ): 977.1 [M /I], 565.0 [M /I /CH2CH /
CH2 /2PhNCS /CCPh]. Anal. Calc. for
C56H49N2P2S2RuI (1104.01): C, 60.92; H, 4.47; N, 2.54. Found: C, 61.46; H, 4.55; N, 2.42%. Spectroscopic data of 4d are as follows: 1H-NMR (CDCl3): d 7.80 /
5.91 (m, 35H, Ph), 4.03 (s, 5H, Cp), 4.56 (s, 2H, CH2), 2.86, 2.13 (m, 4H, PCH2CH2P). 31P-NMR (CDCl3): d 98.87.13C-NMR (CDCl3): d 149.1, 146.3 (SC N), 145.2 / 118.4 (m, Ph and Ca, Cb), 90.3 (Cp), 39.4 (CH2), 29.7 (t, PCH2CH2P, JCP /22.2 Hz). MS (FAB, m /z ): 1096.3 [M /Br], 565.0 [M /Br /CH2(p -C6H4CF3) /
2PhNCS /CCPh]. Anal. Calc. for
C61H50N2F3P2S2BrRu (1175.06): C, 62.35; H, 4.29; N, 2.38. Found: C, 62.57; H, 4.43; N, 2.22%. 3.2. Synthesis of [Ru] / /C /C(Ph)C(SHgCl)N(Ph)C( /NPh)S/ /][Cl] (5) To a 20 ml CH2Cl2 solution of 3 (200.1 mg, 0.214 mmol) was added HgCl2 (174.4 mg, 0.642 mmol). The solution was stirred for 30 min, then the solid HgCl2was filtered off, and the solvent was reduced to 5 ml. This mixture was slowly added to 30 ml of a vigorously stirred diethyl ether. The purple precipitates, thus, formed were filtered and washed with diethyl ether and hexane and dried under vacuum to give the product 5 (220.7 mg, 0.188 mmol) in 88% yield. Spectroscopic data of 5 are as follows:1H-NMR (CDCl3): d 7.72 /6.97
(m, 35H, Ph), 3.85 (s, 5H, Cp), 2.80 /2.50 (m, 4H, PCH2CH2P). 31P-NMR (CDCl3): d 100.53. 13C-NMR (CDCl3): d 173.0, 149.8 (SC N), 143.6 /120.3 (m, Ph and Ca, Cb), 88.8 (Cp), 31.2 (t, PCH2CH2P, JCP /21.0 Hz). MS (FAB, m /z ): 1173.1 [M /Cl], 565.1 [M /Cl /
HgCl /2PhNCS /CCPh]. Anal. Calc. for
C53H44N2P2S2Cl2RuHg (1207.53): C, 52.71; H, 3.67; N, 2.32. Found: C, 53.05; H, 3.75; N, 2.21%.
3.3. Synthesis of [Ru] /C /C(Ph)C( /
O)NHPh]2[Hg2Cl6] (6)
To a 20 ml acetone solution of 3 (100.1 mg, 0.085 mmol) HgCl2 (232.1 mg, 0.85 mmol) was added. The solution was stirred in the air for 3 h, then the solid HgCl2was filtered off and the solvent was reduced to 5 ml. This mixture was slowly added to 30 ml of a vigorously stirred diethyl ether. The purple-red precipi-tates, thus, formed were filtered and washed with diethyl ether and dried under vacuum to give the product 6 (71.5 mg, 0.070 mmol) in 82% yield. Spectroscopic data of 6 are as follows:1H-NMR (CDCl3): d 7.43 /6.71 (m, 35H, Ph), 5.58 (s, 5H, Cp), 3.23, 3.03 (m, 4H, PCH2CH2P). 31P-NMR (CDCl3): d 78.33. 13C-NMR (CDCl3): d 348.7 (t, Ca, JCP /15.4 Hz), 190.1 (C /O), 159.4, 139.0 /120.3 (m, Ph, Cb), 93.2 (Cp), 29.0 (t, PCH2CH2P, JCP /23.3 Hz). MS (FAB, m /z ): 786.1 [1/2M /Hg2Cl6], 565.1 [M /HgCl3 /CCPh /
CONHPh]. Anal. Calc. for C92H80N2O2P4Cl6Ru2Hg2 (2185.51): C, 50.56; H, 3.69; N, 3.06. Found: C, 51.03; H, 3.73; N, 2.93%.
3.4. Single crystal X-ray diffraction analysis of 4c and 6 Single crystals of 6 suitable for an X-ray diffraction study were grown as mentioned above. A single crystal of dimensions 0.45 /0.30 /0.30 mm3 was glued to a
glass fiber and mounted on an SMART CCD diffract-ometer. The diffraction data were collected using 3 kW sealed-tube molybdenum Ka radiation (T /295 K).
Exposure time was 5 s per frame [12]. SADABS [13]
(Siemens area detector absorption) absorption correc-tion was applied, and decay was negligible. Data were processed and the structure was solved and refined by the SHELXTL [14] program. The structure was solved
using direct methods and confirmed by Patterson methods refining on intensities of all data (23 926 reflectios) to give R1 /0.0286 and wR2 /0.0572 [15]
for 8823 unique observed reflections (I /2s (I )).
Hydro-gen atoms were placed geometrically using the riding model with thermal parameters set to 1.2 times that for the atoms to which the hydrogen is attached and 1.5 times that for the methyl hydrogens. The procedure for the structure determination of 4c was similar to that of 6. The final R indices of 4c for I /2s (I ) of R1 /0.0951,
wR2 /0.2123 and R indices of all data of R1 /0.1933,
wR2 /0.2584 are high due to a 30% disorder of the
CH2CH /CH2 group. The structure of 4c is used only
Acknowledgements
The National Science Council of Taiwan, the Repub-lic of China is gratefully acknowledged for support of the work.
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[12] SAINT(Siemens Area Detector Intergration) program, Siemens Analytical X-ray, Madison, WI, 1995.
[13] The SADABSprogram is based on the method of Blessing; see:
R.H. Blessing, Acta Crystallogr. Sect. A 51 (1995) 51.
[14] SHELXTL: Structure Analysis Program, version 5.04, Siemens Industrial Automation Inc., Madison, WI, 1995.
[15] GOF /[a[w (Fo2 /Fc2)2]/(n /p )]1/2, where n and p denote the
number of data and parameters. R1 /(a½½Fo½ /½Fc½½)/a½Fo½,
wR2 /[a[w (Fo 2 /Fc 2 )2]/a[w (Fo 2 )2]]1/2 where w /1/[s2(Fo 2 )/(aP )2/ bP ] and P /[(max; 0, Fo2)/2Fc2]/3.
