Dimeric uranium complexes with bridging phospholyl ligands. Crystal structure of [{U(η5-C4Me4P)(μ-η5-C4Me4P)(BH4)}2]

Synthesis, Structure, and Reactions of Hydride, Borohydride, and Aluminohydride Compounds of the f-Elements

“…The mixed-ring complex (Cp)(COT)U(BH 4 )(THF) was made by reaction of (COT)U(BH 4 ) 2 (THF) with TlCp and was transformed into (Cp)(COT)U(BH 4 )(OPPh 3 ) . Reaction of Cp*U(BH 4 ) 3 with Ktmp (tmp = tetramethylphospholyl) gave (Cp*)(tmp)U(BH 4 ) 2 which was reduced into the corresponding U(III) anion 192 or the neutral dimeric compound [(Cp*)(tmp)U(BH 4 )] 2 by means of sodium amalgam in diethyl ether or toluene, respectively.…”

“…A series of uranium borohydride complexes with 2,4-dimethylpentadienyl (dmpd), ,, 6,6- dimethylcyclohexadienyl (dmch), ,, or tetramethylphospholyl (tmp) ligands ,, have been prepared from U(BH 4 ) 4 and (mesitylene)U(BH 4 ) 3 . The volatile uranium(IV) derivatives LU(BH 4 ) 3 (L = dmpd, dmch, tmp) are, like CpU(BH 4 ) 3 , unstable in coordinating solvents; the crystal structure of (dmpd)U(BH 4 ) 3 has been determined (Figure ) .…”

“…The complexes [M(crown-ether)][L 2 U(BH 4 ) 2 ] (M = Na or K; L = dmpd, dmch, tmp) are stable and extraction of the dmch and tmp derivatives with pentane or toluene gave the neutral compounds [(dmch) 2 U(BH 4 )] x 213 and [(tmp) 2 U(BH 4 )] 2 . , The latter, which is fluxional in solution, was characterized by its crystal structure (Figure ); the two uranium metals are bridged by two μ-η 5 ,η 1 -phospholyl ligands and the tridentate BH 4 ligands are cis to the (UP) 2 ring 63 Crystal structure of [(tmp) 2 U(BH 4 )] 2 .…”

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63 Crystal structure of [(tmp) 2 U(BH 4 )] 2 . (Reprinted with permission from ref . Copyright 1994 Elsevier Science S.A.)

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f‐Block Phospholyl and Arsolyl Chemistry

“…The 1 H NMR spectrum of 55 was investigated in additional detail, and variable‐temperature experiments were performed to determine that a cis ‐/ trans ‐isomerisation equilibrium is in operation in solution owing to fluxional η 1 ‐binding of the Tmp ligand [50] . The solid‐state structure of dinuclear pseudo‐tetrahedral 55 was eventually disclosed in 1994, with U−P distances of the η 5 ‐bound Tmp of 2.945(3) and 2.995(3) Å, and, for the η 1 ‐bound Tmp of 2.996(3) Å [51] . This remains the only report of a structurally authenticated U III monophospholyl complex to date.…”