Hydro-ionothermal syntheses, crystal structures, and properties of five new divalent metal iminophosphonates

摘要

The use of a moderately hydrophobic ionic liquid, 1-butyl-2,3- dimethylimidazolium tetrafluoroborate ([BdMIM][BF _4]), as a cosolvent with water, has been investigated in the synthesis of metal phosphonates. This hydro-ionothermal synthesis has been carried out through a systematic combinatorial investigation of several divalent metal chlorides and two related ligands, iminobis(methylphosphonic acid) and N-methyliminiobis(methylphosphonic acid). These reactions resulted in five new divalent metal phosphonates. We present here the synthetic techniques utilized as well as the X-ray structures and characteristic properties of each of these compounds. Co(HO _3PCH _2NH _2CH _2PO _3H) _2, (1), consists of sheets that are hydrogen bonded together by pairs of P-O?H groups. Co(H _2O) _2(HO _3PCH _2NH _2CH _2PO _3H) _2, (2), consists of chains that are connected through an extensive network of hydrogen bonds. Co(HO _3PCH _2NH(CH _3)CH _2PO _3H) _2, (3), is made up of sheets that are hydrogen bonded together by pairing P-O?H interactions. Zn _3(O _3PCH _2NH _2CH _2PO _3) _2, (4), is isostructural to a previously reported cobalt compound which is a non-porous 3-dimensional network. CuClPO _3CH _2NH _2CH _3, (5), formed as a result of an in situ N-C bond cleavage. Ladders built of Cu-O-P-O 8-membered rings are crosslinked by bridging chloride atoms to form sheets. 1, 3, 4 and 5 have been synthesized using the hydrophobic ionic liquid 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([BdMIM][BF _4]) with water as a cosolvent, while 2 has been synthesized from identical conditions in the absence of the [BdMIM][BF _4]. We also report the microwave assisted hydro-ionothermal synthesis of the known polymorph of 2, Co(H _2O) _2(HO _3PCH _2NH _2CH _2PO _3H) _2, (6), synthesized in two hours providing high quality crystals in good yield. The compounds have been characterized by thermogravimetric analysis and IR spectroscopy, and their magnetic properties have been investigated.