Milap A. Mathur

Trimethylphosphine-haloboranes syntheses and proton magnetic resonance spectra☆

Abstract The compounds (CH3)3PBHnX3−n (where X = Cl, Br or I and n = 0, 1, 2, 3) were synthesized by the halogenation of trimethylphosphine-borane and by the direct coordination of trimethylphosphine with boron triiodide. The proton NMR chemical shifts of the methyl protons show an increasing degree of deshielding as the size or the number of the halogen atoms attached to the boron atom is increased. The deshielding of methyl protons is in general less for the phosphine-boranes than for their amine-borane analogues [(CH3)3NBHnX3−n][21]. The greater difference in the chemical shift difference between (CH3)3NBH3 and (CH33NBHnX3−n (Δ) than between (CH3)3PBH3 and (CH3)3PBHnX3−n (Δ′) shows that the increase in the deshielding produced by increasing the size or the number of the halogen atoms in case of phosphorus compounds is less than in the corresponding nitrogen compounds. The decrease in deshielding for the phosphorus compounds is attributed to the reduction in the interaction between the methyl protons and the halogen atom(s) on the boron atom resulting from the longer bond length in the linkage Cue5f8Pue5f8B than in Cue5f8Nue5f8B.

Iron complexes with isocyanoboryl ligands

Abstract Two stable complexes of C 5 H 5 Fe(CO) 2 with the ligand isocyanoborohydride and the new ligand trimethylamine-isocyanoborane have been characterized. Shifts in the CN stretching frequency are interpreted in terms of N-coordination and metal-cyanide backbonding.