Metallaheteroborane chemistry. Part 12. Synthesis of cationic metallaheteroboranes [2-L-2-(PPh3)-closo-2,1-PdTeB10H9(PPh3)][BF4]; molecular structures of the compounds with L = H2O or CO

Abstract

The reaction of Ag[BF₄] and [2-l-2-(PPh₃)-closo-2,1-PdTeB₁₀H₉(PPh₃)]1 in toluene for 30 min at room temperature and subsequent isolation of the product under aerobic conditions afforded [2-(H₂O)-2-(PPh₃)-closo-2,1-PdTeB₁₀H₉(PPh₃)][BF₄]2 in excellent yield. This complex has been characterised by (IR and ¹¹B NMR) spectroscopy and X-ray crystallography. Crystals of 2·0.89CH₂Cl₂ are monoclinic, space group P2₁/c, with cell dimensions a= 14.073(3), b= 15.640(2), c= 20.262(6)Å and β= 94.80(2)°. A final R factor of 0.038 was calculated for 5595 observed reflections. The Pd–OH₂ distance is 2.208(4)Å and Pd–P(1) is 2.3544(14)Å. Cage interatomic distances include Pd–Te 2.6958(6) and ranges for Pd–B of 2.192(6)–2.299(6) and Te–B of 2.287(6)–2.403(6)Å. The exo-cage B(7)–P(2) distance is 1.950(6)Å. The water molecule in 2 can be displaced by a variety of ligands to produce the cationic palladatelluraborane complexes [2-L-2-(PPh₃)-closo-2,1-PdTeB₁₀H₉(PPh₃)][BF₄][L = CO, CNBu^t, CNC₆H₁₁, NCMe, MeCH(Ph)NH₂, OC₄H₈ or SC₄H₈) in yields ranging from 39 to 93%. Reaction between 2 and a ten-fold excess of PMe₂Ph affords [2,2-(PMe₂Ph)₂-closo-2,1-PdTeB₁₀H₉(PPh₃)][BF₄] in 75% yield. All complexes have been characterised spectroscopically (IR and ¹¹B NMR) and in the case of [2-(CO)-2-(PPh₃)-closo-2,1-PdTeB₁₀H₉(PPh₃)][BF₄]3 by X-ray crystallography. The 3·C₆H₅Me solvate crystallises in the monoclinic space group P2₁/c with Z= 4, a= 14.509(3), b= 10.732(1), c= 31.377(8)Å and β= 97.49(2)°. The final R factor of 0.054 was calculated from 5439 observed reflections. Principal interatomic distances include Pd–Te 2.6897(9), Pd–B 2.195(10)–2.307(9), Te–B 2.262(11)–2.389(9), Pd–P(2) 2.367(2), B(11)–P(1) 1.941(9) and Pd–C(1) 2.003(9)Å.