Table 2 Geometric parameters of the complexes (Å and degrees) optimized at MP2 (full)/6-311G* level

PO1

1.654

1.552

PO2

1.503

1.542

PO3

1.657

1.698

PO4

1.487

1.506

C103

1.414

1.403

H101

0.960

1.510

N1H1

4.040

1.01*

C2N1

1.283

1.322

C2N2

1.394

1.318

C2N3

1.406

1.370

C3N3

1.453

1.443

O2H2

1.875

O3H3

2.300

Bond Angles

Complex 1a

Complex 1b

O1PO2

107.9

110.6

O2PO3

100.1

103.4

O3PO4

107.3

115.3

C103P

116.0

113.8

H101P

109.0

122.2

N1H101

236.0

180.0*

C2N1H1

122.8

122.0

N2C2N1

127.9

120.7

N3C2N2

111.6

119.9

C3N3C2

115.7

123.4

Dihedral Angles

Complex 1a

Complex 1b

O3PO102

108.0

107.2

O4PO102

−137.9

−136.2

C103PO2

186.6

177.3

N1H10102

0.0

0.0