Reactivity of Tetrahalo- and Difluorodiboranes(4) toward Lewis Basic Platinum(0): Bis(boryl), Borylborato, and Doubly Boryl-Bridged Platinum Complexes

The
reaction of the tetrahalodiboranes(4) B2F4,
B2Cl4, and B2Br4 with
a Lewis basic platinum(0) complex led to the isolation of the cis-bis­(difluoroboryl) complex cis-[(Cy3P)2Pt­(BF2)2] (1) and the novel borylborato complexes trans-[(Cy3P)2Pt­{B­(X)–BX3}] (2, X = Cl; 3, X = Br), respectively. The trans influence
of the borylborato group was found to be one of the strongest ever
observed experimentally. Furthermore, the reactivity of little-explored
diaryldifluorodiboranes(4) F2B–BMes2 and
the new derivative F2B–BAn2 (An = 9-anthryl)
toward a range of platinum(0) complexes was investigated. Reactions
with relatively nonbulky platinum(0) complexes led to the formation
of unsymmetrical cis-bis­(boryl) complexes cis-[(R3P)2Pt­(BF2)­(BMes2)] (6, R = Me; 7, R = Et) as well
as the first example of a fourfold-unsymmetrical bis­(boryl) complex,
[(Me3P)­(Cy3P)­Pt­(BF2)­(BMes2)] (12). The use of a more bulky Pt complex provided
access to the unprecedented dinuclear bis­(boryl) complexes [{(iPr3P)­Pt}2(μ-BF2)­(μ-BAr2)] (8, Ar = Mes; 9, Ar = An), which
feature two different μ2-bridging boryl ligands.