Reactivity of Boryl Complexes: Synthesis and Structure of New Neutral and Cationic Platinum Boryls and Borylenes

Abstract

A reactivity study on a series of platinum boryl complexes was performed. The first stable base adducts of cationic haloboryl complexes of the form trans-[Pt{B(Br)-(NMe 2 )}(NCMe)(PCy 3 ) 2 ] + were isolated and fully characterized. The dianion [B 12 Cl 12 ] 2− was introduced as a weakly coordinating anion to complex chemistry forming a A 2 X salt. Through the reaction of trans-[Pt{B(Br)(tBu)}Br(PCy 3 ) 2 ] with BBr 2 tBu, the first highly soluble dinuclear platinum boryl complex, [Pt{B(Br)(tBu)}(μ-Br)(PCy 3 )] 2 , could be synthesized with concomitant buildup of the corresponding phosphine-borane adduct. In contrast to this observation, reaction of trans-[Pt{B(Br)(Mes)}Br(PCy 3 ) 2 ] with BBr 3 leads to the formation of the cationic borylene complex trans-[Pt(BMes)Br(PCy 3 ) 2 ] + by abstraction of the bromo ligand bound mutually trans to the boryl ligand in the precursor and concomitant buildup of [BBr 4 ] − . Reaction of [Pt(PCy 3 ) 2 ] with BCl 3 and subsequent abstraction of the platinum-bound chloro ligand enabled the structural characterization of trans-[Pt(BCl 2 )(PCy 3 ) 2 ] + , which is isoelectronic with the metal-only Lewis pair trans-[Pt(BeCl 2 )(PCy 3 ) 2 ]. The bonding situation in both systems was investigated in detail using quantum chemical calculations. A T-shaped cationic complex, trans-[Pt{B(Br)(Fc)}(PiPr 3 ) 2 ] + , and its precursor trans-[Pt{B(Br)(Fc)}Br(PiPr 3 ) 2 ], both with reduced steric bulk at the phosphine ligands compared with their PCy 3 derivatives, were fully characterized.

Hexahalodiborate Dianions: A New Family of Binary Boron Halides

“…The B−X bond lengths within the BX 3 moieties of the asymmetric units of 1 – 4 vary to some degree (Scheme ), reflecting varying degrees of interactions with the cations or cocrystallized solvent with each halogen substituent in the solid state. Similar variations are observed in [BX 4 ] − (Table ) …”

“…2 and 3 are more borderline cases and appear to be stable species in solution (see the Supporting Information), in agreement with conductimetric measurements on 2. [3a] Thed ianions 2-4 proved to be kinetically significantly more stable than their respective tetrahalodiborane counterparts at room temperature.B X 3 is the most common decomposition product of B 2 X 4 and the only one that is easily detectable by 11 [16] ;673r [17] 1375 [16] ;1368r [17] 886;6 26r 843;(850r) [a] ca. 780r [18] ca.…”

Reactivity of Lewis Basic Platinum Complexes Towards Fluoroboranes

“…Using this Lewis base-Lewis acid system, we also observed an irreversible reaction analogous to the synthesis of T-shaped, cationic platinum-boryl complexes. [39,40] For this purpose, one equivalent of a halide abstraction reagent, Na- resonance of 19 was located at d = 48.5 ppm ( 1 J P-Pt = 2631 Hz), whereas the resonance appears as a doublet due to the 3 J P-F coupling of 9 Hz with the boron-bound fluorine nucleus. In addition, the 19 F{ 1 H} NMR spectrum reveals a resonance at d = À20.5 ppm with a 2 J F-Pt coupling constant of 637 Hz together with the resonance of the CF 3 groups at d = À63.3 ppm.…”

Stepwise isolation of low-valent, low-coordinate Sn and Pb mono- and dications in the coordination sphere of platinum

“… 49 , 50 , 54 , 55 This is in line with the well-documented difficulties in detecting 11 B NMR signals in related cationic borylene complexes of the form [(Cy 3 P) 2 Pt(BRL n )] + ( n = 0, 1). 30 , 32 , 33 , 52 …”