Reactions of (O=)PH(OCH2CH3)2and BrMg(CH2)
Synthesis, reactivity, structures, and dynamic properties of gyroscope like iron complexes with dibridgehead diphosphine cages: pre- vs. post-metathesis substitutions as routes to adducts with neutral dipolar Fe(CO)(NO)(X) rotors
Three routes are explored to the title halide/cyanide complexes trans -Fe(CO)(NO)(X)(P((CH 2 ) 14 ) 3 P) ( 9c-X ; X = Cl/Br/I/CN), the Fe(CO)(NO)(X) moieties of which can rotate within the diphosphine cages (Δ H ‡ /Δ S ‡ (kcal mol −1 /eu −1 ) 5.9/−20.4 and 7.4/−23.9 for 9c-Cl and 9c-I from variable temperature 13 C NMR spectra). First, reactions of the known cationic complex trans -[Fe(CO) 2 (NO)(P((CH 2 ) 14 ) 3 P)] + BF 4 − and Bu 4 N + X − give 9c-Cl /- Br /- I /- CN (75–83%). Second, reactions of the acyclic complexes trans -Fe(CO)(NO)(X)(P((CH 2 ) m CHCH 2 ) 3 ) 2 and Grubbs’ catalyst afford the tris(cycloalkenes) trans -Fe(CO)(NO)(X)(P((CH 2 ) m CHCH(CH 2 ) m ) 3 P) ( m /X = 6/Cl,Br,I,CN, 7/Cl,Br, 8/Cl,Br) as mixtures of Z / E isomers (24–41%). Third, similar reactions of trans -[Fe(CO) 2 (NO)(P((CH 2 ) m CHCH 2 ) 3 ) 2 ] + BF 4 − and Grubbs’ catalyst afford crude trans -[Fe(CO) 2 (NO)P((CH 2 ) m CHCH(CH 2 ) m ) 3 P)] + BF 4 − ( m = 6, 8). However, the CC hydrogenations required to consummate routes 2 and 3 are problematic. Crystal structures of 9c-Cl /- Br /- CN are determined. Although the CO/NO/X ligands are disordered, the void space within the diphosphine cages is analyzed in terms of horizontal and vertical constraints upon Fe(CO)(NO)(X) rotation and the NMR data. The molecules pack in identical motifs with parallel P–Fe–P axes, and without intermolecular impediments to rotation in the solid state.
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- NSF-PAR ID:
- 10163881
- Date Published:
- Journal Name:
- Dalton Transactions
- Volume:
- 45
- Issue:
- 41
- ISSN:
- 1477-9226
- Page Range / eLocation ID:
- 16190 to 16204
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract m CH=CH2(4.9–3.2 equiv;m =4 (a ), 5 (b ), 6 (c )) give the dialkylphosphine oxides (O=)PH[(CH2)m CH=CH2]2(2 a –c ; 77–81 % after workup), which are treated with NaH and then α,ω‐dibromides Br(CH2)n Br (0.49–0.32 equiv;n =8 (a′ ), 10 (b′ ), 12 (c′ ), 14 (d′ )) to yield the bis(trialkylphosphine oxides) [H2C=CH(CH2)m ]2P(=O)(CH2)n (O=)P[(CH2)m CH=CH2]2(3 ab′ ,3 bc′ ,3 cd′ ,3 ca′ ; 79–84 %). Reactions of3 bc′ and3 ca′ with Grubbs’ first‐generation catalyst and then H2/PtO2afford the dibridgehead diphosphine dioxides( 4 bc′ ,4 ca′ ; 14–19 %,n′ =2m +2);31P NMR spectra show two stereoisomeric species (ca. 70:30). Crystal structures of two isomers of the latter are obtained,out ,out ‐4 ca′ and a conformer ofin ,out ‐4 ca′ that features crossed chains, such that the (O=)P vectors appearout ,out . Whereas4 bc′ resists crystallization, a byproduct derived from an alternative metathesis mode, (CH2)12P (=O)(CH2)12(O=)P(C H2)12, as well as3 ab′ and3 bc′ , are structurally characterized. The efficiencies of other routes to dibridgehead diphosphorus compounds are compared. -
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/c6dt03258c
