Studies of the oxovanadium-organophosphonate system: Formation of pyrodiphosphonate and pyrophosphophosphonate units through metal-mediated ligand condensations. The crystal and molecular structures of (Ph4P)2[VO{RP(O)2OP(O)2 R}2] (R=Me, Ph) and (Ph4P)2(n-Bu4N)[(VO)6V{t-BuP(O)2OPO3}6

Abstract

Under solvothermal conditions and in the presence of oxovanadium species. organophosphonates undergo self-condensation reactions or condensation with phosphate to yield pyrodiphosphonate {RP(O)2OP(O)2R}2, or organophos-phonatophosphate units {RP(O)2OPO3}3-. In this fashion, the reactions of (Ph4P)[VO2Cl2] withRPO3H2 (R=CH3,Ph) and Et3N in CH3CN at 110°C yielded (Ph4P)2 [VO{RP(O)2P(O)2R}2](R = CH3(1), Ph (2)). However, the reaction of {Ph4P}[VO2Cl2],t-BuPO3H2 and (n-Bu4N)H2PO4 in acetonitrile at 125°C produced an unusual mixed valence V(IV)/V(III) cluster (Ph4P)2 (n-Bu4N)[(VO)6V{Me3CP(O)2OPO3}6] ⊎3CH3CN (3). Compounds1 and2 exhibit mononuclear molecular anions with the V(IV) center in the common square pyramidal coordination mode. The organodiphosphonate ligands adopt a bidentate coordination mode. The molecular anion of3 consists of a shell constructed of six V(IV) square pyramids linked by pentadentate {Me3CP(O)2OPO3}3- groups. Each organophosphonatophosphate ligand bridges four {VO5}square pyramids of the shell and directs the fifth oxygen donor toward the interior of the cluster, so as to bond to an octahedral V(III) located at the center of the cluster cavity. Crystal data:1, C26H26O5.5P3V0.5: triciinic Pl,a=10.836(2)A,b=ll.418(2)A,c=11.486(2)A,α=82.58(2)°,s=75.29(2)°,γ=75.61(2)°,V=1328.1(7)A3,Z=2, Dcalc=l.362gcm-3;2, C36H32O6.5P3V0.5: monoclinic P21/c,a=12.823(3)A,b=14.318(3)A,c=18.581(4)A,s=94.76(3)°,V=3999.7(13)A3,Z=4, Dcalc=l.342gcm-33, C94H139N4O42P14V7, triclinic Pl,a=13.589(3)A,b=17.835(4)A,c=38.915(8)A,α=81.64(2)°,s=81.58(2)°,γ=82.87(2)°,V=9180(3)A3,Z=3, Dcalc=l.512gcm-3.