| Description |
The chemistry of a r e la t iv e ly simple halophosphine, difluorophosphine, has created a surpr ising amount of controversy and in te re s t in the l i te ra tu re for the la s t 20 years. The re la t iv e base strength of PF2 H vs PF3 , PH3 and related compounds has been questi oned. This work reviews the PF2H l i te ra tu re and examines the unusual or unexplained factors involved, and then delves into the problem via new experimental pathways. An e f fe c t ive route to NiL4 complexes (L = PC 13 , PF3 , PF2 C1, Me2 NPF2 , PF2 H) has been developed to f a c i l i ta t e the study of the Ni-P bond strength in ^ ^ 3 )4 , Ni(PF2 H) 4 and N i (P H 3 ) 4 and related species. Selected ligand exchange reactions are described. Phosphine substituted nickel carbonyl compounds were also of in te re s t . The f i r s t procedure for the qu ant i ta t ive preparation of (CO)3 NiL (L = Me2 NPF2, (Me2 N)2PF and CH3 NCH2 CH2 (CH3 )NPF) is presented. Synthetic routes to two new PF2H complexes, (CO)3 Ni(PF2 H) and (C0)2 N i (PF2 H) 2 are also developed. Both PF2H complexes are f u l ly characterized, and th e i r inf rared data are used to help cor relate the r e la t iv e sigma base/pi acid character of PF2 H. Ligand exchange reactions involving the disubst ituted species are described. PF2 H appears to behave normally with respect to nickel; the re la t iv e sigma base/pi acid character of PF2H is intermediate between those of PF3 and PH3 . Our in te re s t in the chemistry of PF2 H stimulated an in te re s t in P-H compounds in general and (R2 N)2PH type compounds in p a r t ic u la r . Four new secondary aminophosphines (Me2 N)2 PH, CH3 NCH2 CH2 (CH37 n])H, (C0)3 Ni[(Me2 N)2 PH] and (CO)3 Ni[CH3 NCH2 CH2 (CH3 )NPH] have been synthesized and characterized. A new nickel phosphorus cation, (CO) 3 Ni[CH3 NCH2 CH2 (CH3 )NPD+, has also been prepared. New routes to PF2H were also sought. PF2H could not be prepared via the reduction of PF2 C1 by L-Selectride, N-Selectride, KSe le c t r id e , B2 H6, LiAl[0C(CH3)3]3H or [(CH3 )2 CHCH2 ]2 A1H. (Me2 N)2PH and (C0)3 N i[(Me2 N)2 PH] have been investigated as possible precursors for PF2H species. I n i t i a l re s u l ts from the reactions of these species with HF indicate that PF2H and (CO)3 Ni(PF2 H) can be prepared. These reactions are described. |
