Competition between transmetalation and electron transfer in the gas-phase reactions of ytterbium complex trications and the tetraphenylborate anion

Gas-phase ion-ion reactions between the trication, [Yb(L)3]3+ (where L = N,N,N′,N′-tetramethylpyridine-2,6-dicarboxamide), and the tetraphenylborate anion, [BPh4]−, and its sodium bound dimer, [(BPh4)2Na]−, were examined to establish whether ion-pair formation and transmetalation from boron to ytterbium can occur. Ion clusters that were formed with the formal +3 oxidation state for the ytterbium metal centre include: the ion pair [Yb(III)(L)3][BPh4]2+ (m/z 578, (6a)); the ion triplet [Yb(III)(L)3][BPh4]2+ (m/z 1475, (7a)); and [Yb(III)(L)3(BPh4)3Na]+ (m/z 1817, (8a)). In addition, electron transfer from [BPh4]− to [Yb(L)3]3+ resulted in complexes in which the ytterbium metal centre is in the formal +2 oxidation state, which reacted further to yield the ion pairs: [Yb(II)(L)3][BPh4]+ (m/z 1156, (7b)); [Yb(II)(L)2][BPh4]+ (m/z 935, (8b)); and [Yb(II)(L)][BPh4]+ (m/z 714, (9b)). Selected ion pairs were mass isolated and subjected to collision-induced dissociation (CID) to examine if they underwent transmetalation from B to Yb. Most of the observed ytterbium(III) complexes were found to undergo transmetalation. Density functional theory (DFT) calculations were used to determine the energetics for the sequential ion-ion reactions associated with the formation of [Yb(II)(L)2][BPh4]+ as well as its fragmentation reactions via ligand loss (observed experimentally) versus transmetalation (not observed experimentally).