TY - JOUR
T1 - Bis(phosphine)boronium salts. Synthesis, structures and coordination chemistry
AU - Shuttleworth, Timothy A.
AU - Huertos, Miguel A.
AU - Pernik, Indrek
AU - Young, Rowan D.
AU - Weller, Andrew S.
PY - 2013
Y1 - 2013
N2 - The synthesis of a range of bis(phosphine)boronium salts is reported [(R2HP)2BH2][X] (R = Ph, tBu, Cy) in which the counter anion is also varied (X− = Br−, [OTf]−, [BArF4]−, ArF = 3,5-(CF3)2C6H3). Characterization in the solid-state by X-ray diffraction suggests there are weak hydrogen bonds between the PH units of the boronium cation and the anion (X− = Br−, [OTf]−), while solution NMR spectroscopy also reveals hydrogen bonding occurs in the order [BArF4]− < [OTf]− < Br−. [(Ph2HP)2BH2][BArF4] reacts with RhH(PPh3)3, by elimination of H2, forming [Rh(κ1,η-PPh2BH2·PPh2H)(PPh3)2][BArF4] which shows a β-B-agostic interaction from the resulting base stabilised phosphino–borane ligand. Alternatively such ligands can be assembled directly on the metal centre by reaction of in situ generated {Rh(PPh3)3}+ and Ph2HP·BH3 to afford [Rh(κ1,η-PPh2BH2·PPh3)(PPh3)2][BArF4], which was characterised by X-ray crystallography. Addition of H3B·PPh2H to the well-defined 16-electron "T-shaped" complex [Rh(PiBu3)2(PPh3)][BArF4] (characterised by X-ray crystallography) formed of a mixture of base-stabilised phosphino borane ligated complexes [Rh(κ1,η-PR2BH2·PR3)(PR3)2][BArF4] (R = iBu or Ph). These last observations may lend clues to the formation of bis(phosphine)boronium salts in the catalytic dehydrocoupling reaction of phosphine boranes as mediated by Rh(I) compounds.
AB - The synthesis of a range of bis(phosphine)boronium salts is reported [(R2HP)2BH2][X] (R = Ph, tBu, Cy) in which the counter anion is also varied (X− = Br−, [OTf]−, [BArF4]−, ArF = 3,5-(CF3)2C6H3). Characterization in the solid-state by X-ray diffraction suggests there are weak hydrogen bonds between the PH units of the boronium cation and the anion (X− = Br−, [OTf]−), while solution NMR spectroscopy also reveals hydrogen bonding occurs in the order [BArF4]− < [OTf]− < Br−. [(Ph2HP)2BH2][BArF4] reacts with RhH(PPh3)3, by elimination of H2, forming [Rh(κ1,η-PPh2BH2·PPh2H)(PPh3)2][BArF4] which shows a β-B-agostic interaction from the resulting base stabilised phosphino–borane ligand. Alternatively such ligands can be assembled directly on the metal centre by reaction of in situ generated {Rh(PPh3)3}+ and Ph2HP·BH3 to afford [Rh(κ1,η-PPh2BH2·PPh3)(PPh3)2][BArF4], which was characterised by X-ray crystallography. Addition of H3B·PPh2H to the well-defined 16-electron "T-shaped" complex [Rh(PiBu3)2(PPh3)][BArF4] (characterised by X-ray crystallography) formed of a mixture of base-stabilised phosphino borane ligated complexes [Rh(κ1,η-PR2BH2·PR3)(PR3)2][BArF4] (R = iBu or Ph). These last observations may lend clues to the formation of bis(phosphine)boronium salts in the catalytic dehydrocoupling reaction of phosphine boranes as mediated by Rh(I) compounds.
UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-84882786439&origin=resultslist&sort=plf-f&src=s&st1=10.1039%2fc3dt50817j&st2=&sid=62a16d8e95e3ed6b0ca8071737097a18&sot=b&sdt=b&sl=23&s=DOI%2810.1039%2fc3dt50817j%29&relpos=0&citeCnt=12&searchTerm=
U2 - 10.1039/c3dt50817j
DO - 10.1039/c3dt50817j
M3 - Article
C2 - 23715206
SN - 1477-9226
VL - 42
SP - 12917
EP - 12925
JO - Dalton Transactions
JF - Dalton Transactions
IS - 36
ER -