Synthesis and structural studies of selected multifunctional phosphonate and phosphonic acid ligands

The carbanion [(RO)2P(O)][C(O)NEt2]CH− is used to prepare several new carbamoylmethyl phosphonates of the general type [(RO)2P(O)][C(O)NEt2]CH(X), XCH3, C2H5, (CH2)2CN, CH2CH[(RO)2P(O)][C(O)NEt2], (CH2)3OH and CH2C(O)OCH3. In addition, an interesting intramolecular transesterification process for the molecule with X(CH2)3OH and novel hydrolysis chemistry that produces useful phosphonic acids are described. The molecular structure determinations of two compounds, {[(i-PrO)2P(O)][C(O)NEt2]CH}2CH2 (4b) and [NH2C(CH3)2CH2C(O)CH2C(CH3)2+][(HO)PO2CH2C(O)NEt2−] (bd11) are outlined. Compound (bd4b) crystallizes in the triclinic space group P1, with a=9.0996(24), b=12.6604(31), c=16.5711(48) Å, α=68.655(20), β=78.714(22), γ=70.742(19)° and Z=2. The molecular structure confirms that two carbamoylmethyl phosphonate fragments are bonded to a central methyl group. Compound 11 crystallizes in the triclinic space group P1, with a=9.2384(21), b=9.8404(21), c=11.0702(25) Å, α=85.276(18), β=74.477(17), γ=78.644(17)° and Z=2. The molecular structure contains a 2,2,6,6-tetramethyl piperidone cation and a carbamoylmethyl phosphonic acid anion.