Publication details

C=O center dot center dot center dot pi Interaction: A Rare Noncovalent Binding in RC(O)NHP(O)[(NRR2)-R-1](2) Phosphoric Triamide Structures


CHAIJAN Mahnaz Rostami POURAYOUBI Mehrdad NEČAS Marek DAMODARAN Krishnan

Year of publication 2015
Type Article in Periodical
Magazine / Source Phosphorus, Sulfur, and Silicon and the related elements
MU Faculty or unit

Faculty of Science

Field Inorganic chemistry
Keywords CSD; C=O center dot center dot center dot pi; phosphoric triamide; crystal structure
Description In the structure of C6F5C(O)NHP(O)[N(C2H5)(C6H11)](2), in addition to N-H center dot center dot center dot O=P hydrogen bond, the oxygen atom of P=O group is involved in the P=O center dot center dot center dot pi interaction (O-P center dot center dot center dot Cg = 3.507(1) angstrom, Cg is the centroid of C6F5 ring). Moreover, a noncovalent C=O center dot center dot center dot pi interaction takes part in the crystal packing, O-C center dot center dot center dot Cg = 3.159(1) angstrom. The C=O center dot center dot center dot pi interaction is the interesting feature of this structure, as a Cambridge Structural Database analysis (CSD; Allen, Acta Cryst. 2002, B58, 380-388) of 149 structures with a C(O)NHP(O)[N](2) skeleton shows that such an interaction exists only in 4 structures. The dihedral angle between the aromatic ring and the plane defined by the atoms of [C][N]C=O segment is 66.66 degrees. The C=O bond length in the present structure (of 1.2148(18) angstrom) is within the expected range for compounds with a C(O)NHP(O)[N](2) segment; however, due to the electronic effect caused by C6F5 group, it is in the region of the short bond lengths for analogous structures deposited in the CSD (1.18-1.26 angstrom). The P=O (1.4831(10) angstrom) and P-N (1.6340(12) angstrom and 1.6424(12) angstrom) bond lengths are standard for a phosphoric triamide structure and the P-N bond of C(O)NHP(O) segment (1.6980(12) angstrom) has an expected longer value relative to the other P-N bonds. The bond-angle sums around the tertiary nitrogen atoms (SUM = 2 x P-N-C + C-N-C) are 357.8 degrees and 352.0 degrees that show few deviations from the planar value of 360 degrees. The more pyramidal N atom is oriented so that the corresponding lone electron pair is anti with respect to the P=O group.

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