Synthesis And Characterization Of Alkai Metal Complexes Bearing 1,2,4-diazaphospholide Ligands And Their Sulfur (Selenium) Potassium Phosphate Salts

1,2,4-Diazaphospholide（dp）is a unique class of pentase heterocyclic ligands,found that due to the synergistic action of N and P（σ²λ³）atomic orbitals,the auxiliary different substituents together change the chemical environment of the pentasypyrazole ring,and then affect its physicochemical properties,showing other N（or P）pentase heterocyclic rings（such as triazole,pyrazole,oxadiazole,thiadiazole and phosphine heterogeneous,etc.）significantly different redox characteristics and the special stability of their free radicals.After nearly 20years of basic research and exploration,it has been found that complexes can be formed with the main group,transition and rare earth metals in a variety of coordination modes.However,lithium,sodium,and potassium salts of phosphamide can be used as precursors to the reaction,and their crystal structure is not well understood.To this end,six lithium,sodium and potassium complexes rich in structural novel coordination modes were synthesized,and X-ray single crystal diffraction,nuclear magnetic（NMR）and infrared（IR）were characterized.Previous work showed that the phosphine pyrazole anion has certain redox characteristics,for which the tert-butylphosphinopyrazole potassium salt（[（3,5-t Bu₂dp）K]_n）was reacted with S and Se to obtain two structurally novel 18-crown-6 ether-stabilized potassium sulfate and potassium selenium phosphate complexes.This article is described in detail below:We have synthesized the following six phosphopyrazole alkali metal complexes with different coordination modes,whose structures have not been obtained before.[（η¹,η¹-3,5-i Pr₂dp）Li（THF）₂]₂,[（3,5-Ph₂dp）（THF）Na]₄·4toluene,[（3,5-t Bu₂dp）Na]_n,[（3,5-t Bu₂dp）K]_n,[{（η⁵:η⁵:η²-3,5-i Pr₂dp）K}{η²:η⁵:η¹-3,5-i Pr₂dp)K（THF）}]_n,and[{（η⁵:η²-3,5-Ph₂dp）K（THF）}{（η⁵-3,5-Ph₂dp）K（THF）}]_n.We found that the lithium ion in the complex[（η¹,η¹-3,5-i Pr₂dp）Li（THF）₂]₂ coordinated with phosphazoline ligand inη¹ mode,and the structure contained THF solvent molecules.The sodium ion in the complex[（3,5-Ph₂dp）（THF）Na]₄·4 toluene coordinates with the ligand inη¹ andη² coordination modes,formingatetramerstructure.Thecomplex[{（η⁵:η²-3,5-Ph₂dp）K（THF）}{（η5-3,5-Ph₂dp）K（THF）}]_n potassium ion coordinates with the ligand inη² andη⁵ modes.Complex[（3,5-t Bu₂dp）Na]_n is coordinated inη¹ andη²coordination modes,which is a solvent-free polymer structure.However,the complex[{（η⁵:η⁵:η²-3,5-i Pr₂dp）K}{η²:η⁵:η¹-3,5-i Pr₂dp)K（THF）}]_n presents an infinitely extended step-like structure,and the steps are formed by the interaction between sodium ions and ligands byη²,and there is a transition between every two steps.Complex[（3,5-t Bu2dp）K]n also presents a solvent-free step structure passing through axis A.The step in the structure is formed by theη² interaction between potassium ions and ligand.Complexes[（3,5-t Bu₂dp）K]_nand[{（η⁵:η⁵:η²-3,5-i Pr₂dp）k}{η²:η⁵:η¹-3,5-i Pr₂dp)k（THF）}]_n have similar structures to those reported previously.Of the six unique and novel phosphine pyrazole lithium,sodium and potassium metal complexes synthesized for the first time,we have only obtained the crystal structure of the complex,but in solution,the complex continues to maintain its original structure or completely dissociate and partially dissociate,we do not know.Therefore,we took the tert-butylphosphinopyrazole potassium salt[（3,5-t Bu₂dp）K]_n as an example and analyzed it for a Dosy analysis..According to the Stokes Einstein equation of 1H Dosy NMR experiment,the corresponding particle diameter is 7.345（?）,which is close to the crystal structure of[（3,5-t Bu₂dp）K]_n（7.113）（?）,indicating that the complex[（3,5-t Bu₂dp）K]_n dissociates into monomer in solution,and the structure of the complex in solution is obtained.Previous research work showed that the phosphine pyrazole anion can be oxidized by Fe³⁺,Cu²⁺to obtain divalent anionic radicals,oxidized by Bi³⁺and Sb³⁺to give the corresponding phosphine pyrazole free radicals and can also be oxidized by oxygen,we oxidized the[（3,5-t Bu₂dp）K]_n with sulfur and selenium,ter-butyl potassium thiophosphate and ter-butyl potassium selenophosphate were obtained.We compared three complexes for their bond length.Compared with[（3,5-t Bu₂dp）K]_n,the C-P bond of[η³（S,P,S）-3,5-t Bu₂dp-（μ-K）（S₂）（[18]crown-6）]is 0.07-0.09（?）longer than it;the N-N bond is0.01（?）longer than it;the C-N bond is 0.05-0.06（?）shorter than it.the C-P bond of[η³（Se,P,Se）-3,5-t Bu₂dp-（μ-K）（Se₂）（[18]crown-6）]is 0.05-0.07（?）longer than it;the N-N bond is 0.06（?）longer than it;the C-N bond is 0.03-0.06（?） shorter than it.