A quantum chemical study on structures of

(C)-(R)-2,2-bis(diphenylphosphinoyl)-1,1 0-binaphthyl

and its hydroquinone complex

C. Yenikayaa, C. Ogretirb,*, H. Berberc

aChemistry Department, Faculty of Arts and Sciences, Dumlupinar University, Kutahya, TurkeybChemistry Department, Faculty of Arts and Sciences, Osmangazi University, 26040 Eskisehir, Turkey

cChemistry Department, Faculty of Sciences, Anadolu University, 26040 Eskisehir, Turkey

Received 24 February 2004; accepted 18 August 2004

Abstract

The (C)-(R)-2,2-bis(diphenylphosphinoyl)-1,1 0-binaphthyl ((C)-(R)-BINAPO) and its cocrystal with hydroquinone (HQ) (1:1) were

studied theoretically with AM1, PM3, MNDO and MINDO/3 semi-empirical methods to elucidate their structures. The bond lengths and

angles from theoretical studies of molecules (C)-(R)-BINAPO and (C)-(R)-BINAPO/HQ with one molecule of water were found to be as

expected. The results were compared with the previously obtained experimental data and MNDO and PM3 results were found to be the best

fit for bond lengths and angles of (C)-(R)-BINAPO and for the complex of (C)-(R)-BINAPO/HQ, respectively.

q 2004 Elsevier B.V. All rights reserved.

Keywords: Hydrogen bonding; Cocrystal; X-ray diffraction; Quantum chemical studies; Semi-empirical methods; (C)-(R)-2,2-bis(diphenylphosphinoyl)-1,10-

binaphthyl

1. Introduction

The hydrogen bond is the strongest of all intermolecular

bonds found in organic crystals and the role played by

hydrogen bonds in controlling the molecular structure of

crystalline solids should not be underestimated. In the past

decade, there has been a substantial increase in the use of

hydrogen bonds as design elements in organic solids [1–6].

The PaO group of a phosphine oxide is an excellent

hydrogen bond acceptor. Triphenylphosphine oxide (TPPO)

is a good hydrogen bond acceptor and forms large, high

quality crystals when cocrystallized with a variety of

hydrogen bond donors, a procedure that was promoted as

a crystallization aid for compounds that do not crystallize

well on their own [7]. There are a few examples of hydrogen

bonded complexes for TPPO and alcohols (diphenylmetha-

nol) [8] or phenols [9–11]. Although the hydrogen bond

0166-1280/$ - see front matter q 2004 Elsevier B.V. All rights reserved.

doi:10.1016/j.theochem.2004.08.054

* Corresponding author. Tel.: C90 222 229 04 33; fax: C90 222 239 35

78.

E-mail address: cogretir@ogu.edu.tr (C. Ogretir).

geometry is very similar in all of the cocrystals, consisting

of a single linear bond one of the cocrystals of phenols,

TPPO/phenol, is different. It was prepared from a 1:1

mixture of the components, the material isolated is a 2:3

TPPO/phenol cocrystal [12]. The phosphine oxide in the

present study, (C)-(R)-2,2-bis(diphenylphosphinoyl)-1,1 0-

binaphthyl ((C)-(R)-BINAPO) and hydroquinone (HQ)

produced 1:1 complex with one water molecule. The

traditional X-ray diffraction techniques and theoretical

studies allow the determination of the positions of the

atoms in the compounds under study for suitable sys-

tems [13–15]. The continuous increase in development of

the computer technology and in turn with tremendous

development in sophistication of software which are

suitable to apply in structure–reactivity relations [16,17],

reaction mechanism [18–20], corrosion [21–23] and in

some biological processes [24,25] has tempted us to study

the structure of the title compound to search the

parallelism of the computed results with the experimental

ones. We had compared the results, for bond lengths and

bond angles as well as hydrogen bonding in the cocrystal of

Journal of Molecular Structure: THEOCHEM 713 (2005) 171–177

www.elsevier.com/locate/theochem

C. Yenikaya et al. / Journal of Molecular Structure: THEOCHEM 713 (2005) 171–177172

(C)-(R)-BINAPO and hydroquinone, between quantum

chemical results in the gas phase and X-ray structural

studies. The data from previous X-ray structural study were

kindly provided by one of us [26,27].

2. Method of calculation

Theoretical calculation were carried out at the Restricted

Hartree–Fock level using MINDO/3, MNDO, PM3 and

AM1 semi-empirical SCF-MO methods in the MOPAC 7.0

program [28], implemented on an Intel Pentium Program

400 MHz computer. Initial estimates for the geometries of

all were obtained by a molecular mechanics program (CS

Chemoffice Pro for Windows) [29], followed by full

optimization of all geometrical variables (bond lengths,

bond angles and dihedral angles), without any symmetry

constraint, using the semi-empirical MINDO/3, MNDO,

PM3, AM1 quantum chemical methods in the MOPAC 7.0

program. The molecular plots for the (C)-(R)-BINAPO and

cocrystal of (C)-(R)-BINAPO/HQ were produced by the

CRYSTALS [30] and CAMERON [31] programs.

3. Results and discussion

3.1. The crystal and molecular structure

of (C)-(R)-BINAPO

Crystals of (C)-(R)-BINAPO, suitable for single crystal

X-ray diffraction, were grown as colorless needless from

ethyl acetate (Fig. 1). The compound crystallizes in

non-centrosymmetric monoclinic space group P21, with

Fig. 1. The structure of (C)-(R)-BINAPO drawing by CAMERON.

two formula units per unit cell. There is one crystal-

lographically distinct molecule in the asymmetric unit and

the two halves of the molecule are distinct. This provides

two different phosphorus sites in the asymmetric unit.

Table 1 lists selected bond lengths and angles. The geometry

of (C)-(R)-BINAPO molecule is found to be as expected.

The dihedral angle between the least-squares planes of two

naphthyl rings is 85.808, which is larger than that found in

(C)-binaphthol (80.808) [32]. There is only one crystal-

lographically characterized example of a chiral BINAPO

complex, the material crystallized from hot acetic acid and

ethyl acetate; (S)-(K)-BINAPO, (1R)-(K)-camphorsulfo-

nic acid and acetic acid, which also contains an ethyl acetate

as crystal solvent. In this complex, the angle between the

naphthyl rings is 89.78 [33]. All these experimental results

were confirmed in the present study (Tables 1 and 4). The

molecule ((C)-(R)-BINAPO) in gas phase was studied with

MINDO/3, MNDO, PM3 and AM1 semi-empirical methods

at 20 8C at which the experimental values were obtained

[26].

Table 1 lists the gas phase computation results for

MINDO/3, MNDO, PM3 and AM1 semi-empirical methods

as well as the previously studied experimental data for (C)-

(R)-BINAPO [26]. Among the applied methods, MNDO

seems to give better results for both bond lengths and angles

of (C)-(R)-BINAPO, suggested with the mean values for

percentage of difference between theoretical and exper-

imental results. MNDO method also gives the best fit for the

dihedral angle between the least-squares planes of two

naphthyl rings for the molecules of (R)-(C)-BINAPO

(Table 4).

3.2. The crystal and molecular structure of the 1:1 cocrystal

of (C)-(R)-BINAPO/HQ

Crystals of the cocrystal of (C)-(R)-BINAPO with

hydroquinone, suitable for single crystal X-ray diffraction,

were grown as colorless plates from acetone. The

compound crystallizes in the non-centrosymmetric orthor-

hombic space group P212121, with four formula units per

unit cell. There is one crystallographically distinct

cocrystal in the asymmetric unit and the two halves of

the (C)-(R)-BINAPO are distinct. This provides two

different phosphorus sites in the asymmetric unit. The

asymmetric unit contains one (C)-(R)-BINAPO molecule,

one hydroquinone molecule and one water molecule. The

molecular structure and the packing diagram of 1:1

cocrystal of (C)-(R)-BINAPO/HQ are shown in Figs. 2

and 3, respectively. Table 2 lists selected bond lengths

and angles. The geometries of (C)-(R)-BINAPO and

hydroquinone molecules are as seen elsewhere. The

dihedral angle between the least-squares planes of two

naphthyl rings is 82.518, which is very close to that found

in (C)-binaphthol (80.808) [32] and smaller than that

found in the cocrystal of (S)-(K)-BINAPO, (1R)-(K)-

camphorsulfonic acid and acetic acid (89.708) [33].

Table 1

Selected bond lengths and angles obtained from quantum chemical calculations and obtained from previous experimental studies for (C)-(R)-BINAPO

AM1 % (a) PM3 % (b) MNDO % (c) MINDO/3 % (d) Exp. [26]

Bond lengths (A)

P1–O1 1.727 16.926 1.640 11.036 1.517 2.708 1.536 3.995 1.477(2)

P1–C21 1.645 9.066 1.900 5.030 1.775 1.879 1.882 4.035 1.809(3)

P2–O2 1.745 18.305 1.641 11.254 1.518 2.915 1.536 4.136 1.475(2)

P2–C39 1.693 6.309 1.839 1.771 1.775 1.771 1.876 3.818 1.807(4)

P1–C27 1.685 6.752 1.839 1.771 1.777 1.660 1.878 3.929 1.807(3)

P1–C2 1.677 7.552 1.882 3.749 1.785 1.599 1.894 4.410 1.814(3)

P2–C33 1.659 7.782 1.909 6.115 1.780 1.056 1.885 4.780 1.799(4)

P2–C12 1.667 8.205 1.877 3.359 1.788 1.542 1.895 4.350 1.816(3)

Mean value 10.1 5.5 1.9 4.2

Bond angles (8)

O1–P1–C27 169.5 51.746 122.5 9.669 108.2 3.133 110.6 0.985 111.7(2)

C27–P1–

C21

96.1 9.680 94.1 11.560 108.7 2.162 107.1 0.658 106.4(2)

C27–P1–C2 93.0 11.932 118.5 12.216 108.8 3.030 110.6 4.735 105.6(2)

O2–P2–C33 92.2 16.787 123.7 11.643 108.3 2.256 109.7 0.993 110.8(2)

C33–P2–

C12

116.2 8.295 97.2 9.413 105.4 1.771 113.9 6.151 107.3(2)

C33–P2–

C39

93.6 12.687 94.6 11.754 108.7 1.399 107.0 0.187 107.2(2)

O1–P1–C21 89.5 19.946 100.0 10.555 110.2 1.431 108.3 3.131 111.8(2)

O1–P1–C2 91.6 21.319 115.1 1.134 113.3 2.680 109.6 5.858 116.42(14)

C21–P1–C2 122.0 17.195 95.5 8.261 107.5 3.266 110.4 6.052 104.1(2)

O2–P2–C12 93.7 17.987 97.8 14.398 109.9 3.807 109.6 4.070 114.25(14)

O2–P2–C39 161.2 44.574 123.7 10.942 108.2 2.960 109.1 2.152 111.5(2)

C39–P2–

C12

99.7 5.318 117.2 11.301 112.5 6.838 113.9 8.167 105.3(2)

Mean value 19.8 10.2 2.9 3.6

(a) (jAM1KExp.j/Exp.)!100; (b) (jPM3KExp.j/Exp.)!100; (c) (jMNDOKExp.j/Exp.)!100; (d) (jMINDO/3KExp.j/Exp.)!100.

C. Yenikaya et al. / Journal of Molecular Structure: THEOCHEM 713 (2005) 171–177 173

All these experimental results were confirmed in the

present study (Tables 2–4). In (C)-(R)-BINAPO/HQ,

there are three different hydrogen bonds in the unit cell

with a chain motif along the a axis. The water molecule is

located between the hydroquinone and BINAPO and it is

hydrogen bonded to both molecules. The first hydrogen

Fig. 3. View of one unit cell of the (C)-(R)-BINAPO/HQ complex drawing

by CAMERON.

Fig. 2. The structure of (C)-(R)-BINAPO/HQ complex drawing by

CAMERON.

Table 2

Selected bond lengths and angles obtained from quantum chemical calculations and obtained from previous experimental studies for (C)-(R)-BINAPO/HQ

(comp1)

AM1 % (a) PM3 % (b) MNDO % (c) MINDO/3 % (d) Exp. [27]

Bond lengths (A)

P1–O1 1.481 0.604 1.490 0.000 1.478 0.805 1.502 0.805 1.490(2)

P1–C1 1.659 8.343 1.826 0.884 1.666 7.956 1.734 4.199 1.810(3)

P1–C11 1.633 9.829 1.799 0.663 1.626 10.215 1.771 2.209 1.811(4)

P1–C17 1.626 10.463 1.812 0.220 1.635 9.967 1.717 5.452 1.816(4)

P2–O2 1.474 0.741 1.486 0.067 1.473 0.808 1.502 1.145 1.485(2)

P2–C1 1.659 8.190 1.845 2.103 1.664 7.914 1.736 3.929 1.807(4)

P2–C17 1.623 10.282 1.814 0.276 1.634 9.674 1.716 5.141 1.809(4)

P2–C11 1.633 9.928 1.798 0.827 1.625 10.370 1.710 5.681 1.813(4)

O3–H3 0.981 15.276 0.952 11.868 0.978 14.924 0.876 2.938 0.851(0.038)

O4–H4 0.970 15.202 0.953 13.183 0.961 14.133 0.957 13.658 0.842(0.039)

O5–H5 0.961 6.426 0.952 7.303 0.961 6.426 0.967 5.842 1.027(0.057)

O3/O1 3.093 15.238 2.988 11.326 3.047 13.525 2.907 8.308 2.684(0.004)

O4/O5 3.065 11.984 3.034 10.851 3.052 11.509 3.055 11.619 2.737(0.006)

H3/O1(HB3)

2.118 14.548 2.080 12.493 2.099 13.521 2.097 13.413 1.849(0.040)

H4/O5(HB2)

2.095 10.205 2.081 9.469 2.082 9.521 2.087 9.784 1.901(0.041)

Mean value 9.8 5.4 9.4 6.3

Bond angles (8)

O1–P1–C1 117.5 1.732 115.3 0.173 117.5 1.732 117.2 1.472 115.5(2)

C1–P1–C11 105.0 0.382 105.3 0.669 105.2 0.574 105.8 1.147 104.6(2)

C1–P1–C17 105.2 2.502 104.7 2.966 104.9 2.780 105.3 2.410 107.9(2)

O2–P2–C1 113.8 1.386 114.3 0.953 114.2 1.040 114.1 1.127 115.4(2)

C1–P2–C17 106.1 1.531 104.8 0.287 105.4 0.861 105.8 1.244 104.5(2)

C1–P2–C11 106.0 1.338 106.2 1.530 105.9 1.243 106.6 1.912 104.6(2)

O1–P1–C11 109.8 0.543 111.7 1.178 110.4 0.000 110.1 0.272 110.4(2)

O1–P1–C17 110.1 0.721 112.4 1.353 109.8 0.992 109.3 1.443 110.9(2)

C11–P1–

C17

108.8 1.587 106.8 0.280 108.6 1.401 108.8 1.587 107.1(2)

O2–P2–C17 110.7 0.539 112.6 1.168 111.3 0.000 110.6 0.629 111.3(2)

O2–P2–C11 112.4 0.988 112.6 1.168 111.9 0.539 111.6 0.270 111.3(2)

C17–P2–

C11

107.4 1.648 105.7 3.205 107.8 1.282 107.6 1.465 109.2(2)

O4–H4/O5 178.5 3.942 178.8 4.117 178.7 4.059 178.8 4.117 171.73(3.88)

O3–H3/O1 172.4 3.699 158.7 4.541 162.7 2.135 153.5 7.669 166.25(3.80)

Mean value 1.6 1.7 1.3 1.9

(a) (jAM1KExp.j/Exp.)!100; (b) (jPM3KExp.j/Exp.)!100; (c) (jMNDOKExp.j/Exp.)!100; (d) (jMINDO/3KExp.j/Exp.)!100.

C. Yenikaya et al. / Journal of Molecular Structure: THEOCHEM 713 (2005) 171–177174

bond (HB1) is between PaO group and water molecule

(1.815(0.060) A, 155.88(5.00)8), the second one (HB2) is

between the one of the OH groups of hydroquinone

molecule and water molecule (1.901(0.041) A,

171.73(3.88)8) and the third one (HB3) is between the

other OH group of hydroquinone molecule and the PaO

group of BINAPO which is not bonded to the water

molecule (1.849(0.040) A, 166.25(3.80)8). This can be

seen easily from the schematic illustration of hydrogen

bonding for the 1:1 cocrystal of BINAPO/HQ in Fig. 4.

The molecule ((C)-(R)-BINAPO/HQ) in gas phase was

studied with MINDO/3, MNDO, PM3 and AM1 semi-

empirical methods at 20 8C at which the experimental

values were obtained [27]. Since it was not possible to

compute the bond length and angles for the unit cell of

(C)-(R)-BINAPO/HQ which has more than 100 atoms

(i.e. limit of allowed number of atoms) within the chain,

hydrogen bond pattern was represented by two molecules,

comp1 and comp2 (Fig. 5).

The data for the comp1 are given in Table 2. PM3 method

gives more preferable outcomes for the bond lengths of

(C)-(R)-BINAPO/HQ complex (comp1). On the other hand,

all available methods including PM3 offer good results for

the angles, which are suggested with the mean values for

percentage of difference between theoretical and exper-

imental results. Hydrogen bond length between H5 and O2

(HB1) is not obtainable from comp1; therefore, comp2 can

be used for both the bond length of HB1 and the angle of

O5–H5/O2. PM3 also gives better results for these data.

Although PM3 offers reasonable outcomes for the other

data for comp2, the other data (Table 3) and dihedral angles

(Table 4) from theoretical methods are inconsistent for

Table 3

Selected bond lengths and angles obtained from quantum chemical calculations and obtained from previous experimental studies for (C)-(R)-BINAPO/HQ

(comp2)

AM1 % (a) PM3 % (b) MNDO % (c) MINDO/3 % (d) Exp. [27]

Bond lengths (A)

P1–O1 1.596 7.114 1.667 11.879 1.666 11.812 1.653 10.940 1.490(2)

P1–C1 1.604 11.381 1.773 2.044 1.737 4.033 1.840 1.657 1.810(3)

P1–C11 1.589 12.258 1.757 2.982 1.757 2.982 1.867 3.092 1.811(4)

P1–C17 1.583 12.830 1.729 4.791 1.762 2.974 1.872 3.084 1.816(4)

P2–O2 1.488 0.202 1.518 2.222 1.521 2.424 1.541 3.771 1.485(2)

P2–C1 1.641 9.186 1.832 1.384 1.761 2.546 1.863 3.099 1.807(4)

P2–C17 1.622 10.337 1.801 0.442 1.770 2.156 1.879 3.870 1.809(4)

P2–C11 1.618 10.756 1.810 0.165 1.772 2.261 1.886 4.026 1.813(4)

O3–H3 0.972 14.219 0.949 11.516 0.949 11.516 0.951 11.751 0.851(0.038)

O4–H4 0.958 13.777 0.971 15.321 0.951 12.945 0.951 12.945 0.842(0.039)

O5–H5 0.959 6.621 0.965 6.037 0.943 8.179 1.005 2.142 1.027(0.057)

O5/O2 2.681 3.734 2.760 0.898 6.535 134.650 6.842 145.673 2.785(0.005)

O4/O5 2.803 2.411 3.187 16.441 4.066 48.557 4.069 48.666 2.737(0.006)

H5/O2(HB1)

2.114 16.474 1.805 0.551 5.922 226.281 10.623 485.289 1.815(0.060)

H4/O5(HB2)

2.377 25.039 2.823 48.501 4.635 143.819 2.087 9.784 1.901(0.041)

Mean value 10.4 8.3 41.1 50.0

Bond angles (8)

O1–P1–C1 105.1 9.004 102.8 10.996 109.8 4.935 105.4 8.745 115.5(2)

C1–P1–C11 112.7 7.744 111.9 6.979 112.1 7.170 114.2 9.178 104.6(2)

C1–P1–C17 111.7 3.522 112.7 4.449 107.5 0.371 109.0 1.019 107.9(2)

O2–P2–C1 112.7 2.340 113.3 1.820 111.5 3.380 110.8 3.986 115.4(2)

C1–P2–C17 107.5 2.871 108.3 3.636 112.7 7.847 113.7 8.804 104.5(2)

C1–P2–C11 106.3 1.625 104.3 0.287 103.6 0.956 133.4 27.533 104.6(2)

O1–P1–C11 105.0 4.891 105.3 4.620 105.0 4.891 106.8 3.261 110.4(2)

O1–P1–C17 111.6 0.631 113.0 1.894 115.4 4.058 113.9 2.705 110.9(2)

C11–P1–

C17

110.6 3.268 110.6 3.268 107.0 0.093 107.6 0.467 107.1(2)

O2–P2–C17 111.4 0.090 112.2 0.809 110.0 1.168 109.4 1.707 111.3(2)

O2–P2–C11 111.0 0.270 112.3 0.898 112.3 0.898 111.2 0.090 111.3(2)

C17–P2–

C11

107.6 1.465 105.8 3.114 106.5 2.473 106.6 2.381 109.2(2)

O5–H5/O2 116.3 25.391 169.8 8.930 127.2 18.399 154.5 0.885 1.490(2)

O4–H4/O5 105.3 38.683 103.1 39.964 48.4 71.816 48.2 71.933 1.810(3)

Mean value 7.3 6.5 9.2 10.2

(a) (jAM1KExp.j/Exp.)!100; (b) (jPM3KExp.j/Exp.)!100; (c) (jMNDOKExp.j/Exp.)!100; (d) (jMINDO/3KExp.j/Exp.)!100.

Table 4

Dihedral angles between the least-squares planes of two naphthyl rings for

C. Yenikaya et al. / Journal of Molecular Structure: THEOCHEM 713 (2005) 171–177 175

comp2. The dihedral angle between the least-squares planes

of two naphthyl rings is found to be the best fit with the

result of PM3 method for the comp1 (Table 4).

The consistent results obtained for comp1 comprise the

main difference from the results of comp2, which might be

due to the arrangements of the (C)-(R)-BINAPO, HQ and

H2O molecules on the hydrogen bond pattern of the

complex. We might predict from this difference that

comp1 is the more suitable model for the unit cell of the

complex.

the molecules of (R)-(C)-BINAPO and (R)-(C)-BINAPO/HQ

Compound Dihedral angles (8)

AM1 PM3 MNDO MINDO/3 Exp.

(R)-(C)-BINAPO 148.9 117.3 87.8 89.2 85.80 [26]

(comp1) 89.4 83.9 89.1 86.0 82.51 [27]

(comp2) 136.1 140.2 130.7 126.1 82.51 [27]

4. Conclusion

All available hydrogen bond donors and acceptors are

involved forming hydrogen bonds in the cocrystal. This

is in accord with the Etter rules that in the solid state all

available acidic H atoms participate in hydrogen bonds

[1]. The crystal structures of the (R)-(C)-BINAPO and

its hydroquinone cocrystal have been thoroughly exam-

ined previously and they revealed that there are no

apparent holes in the packing diagrams due to dense

Fig. 4. Schematic illustration of hydrogen bonded chain in BINAPO/HQ.

Fig. 5. Representing molecules of (C)-(R)-BINAPO/HQ complex.

C. Yenikaya et al. / Journal of Molecular Structure: THEOCHEM 713 (2005) 171–177176

packing behaviour in the lattice. The cocrystal of

hydroquinone with (R)-(C)-BINAPO (1:1) gave chain

structure [26,27]. Comparable results were obtained

between experimental and theoretical studies for the

bond lengths and angles. MNDO gave better results for

both bond lengths and angles for (R)-(C)-BINAPO. As

the molecule becomes more complex, PM3 provided

handier results. However, this point needs to be checked

out in future by performing the same methods for more

phosphine oxides and cocrystals. Small differences for

the bond lengths and angles between theoretical and

experimental results might be due to the phase

differences.

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