[3]Ferrocenophanes with the bisphosphanotetryl bridge: inorganic rings on the way to tetrylenes

Abstract

A series of [3]ferrocenophanes with functional P-E-P motifs (E = group 14 fragments) is reported. Out of these, the silicon compounds with the general formula Fe(C5H4PtBu)2SiXY (XY = Cl2, Br2, I2, H2, HCl) have been characterized by spectroscopic means and the bonding situation was analyzed using X-ray crystallography and quantum chemical calculations. Despite the two stereogenic phosphanyl centers, most of the [3]ferrocenophanes have been obtained as single isomers in the course of stereospecific reactions. The corresponding stannylene Fe(C5H4PtBu)2Sn has been obtained in the form of its dimeric adduct.

A Stabilized Bisphosphanylsilylene and Its Heavier Congeners

“…In good agreement with the observation of both isomers, the Gibbs free energy difference is small between them (Δ G ( 2 a – 2 b ) =0.9 kcal mol −1 Δ G ( 4 a – 4 b ) =−0.8 kcal mol −1 (ωB97XD/6‐31+G*, 298 K, 1 bar) and these isomers ( 2 and 4 ) are more stable than the corresponding E=E bonded dimeric structures by 25.6 kcal mol −1 (E=Sn) and 28.1 kcal mol −1 (E=Pb). It should be mentioned that in the present work we have located more stable isomers for 4 than previously reported, showing that the four‐membered ring structure is more preferred with respect to the E=E double bonded one as was considered before …”

“…Reaction of lithium phosphanide 1 with tetrel dihalides of tin through lead, gave very diverse results. Reaction of SnCl 2 or SnBr 2 with 1 resulted in formation of the dimeric stannylene 2 (Scheme ) which showed characteristic NMR parameters and coupling patterns ( δ ( 119 Sn)=+419 ppm (td, 1 J SnP =1204 Hz, 1 J SnP =735 Hz), ( δ ( 31 P)=−31.4 ppm (P exo ) and −92.6 ppm (P endo )) in agreement with other dimeric phosphanylstannylenes featuring a mutual donor–acceptor motif based on NMR spectroscopy .…”

“…All Sn–P contacts in 2 are shorter than those in a related ate‐complex (2.671(4)–2.702(3) Å) but significantly longer compared to monomeric bisphosphanylstannylenes, with (2.4458(8) Å), or without (2.567 Å, 2.5757(7) Å) P–Sn π interactions. Within the central P 2 Sn 2 ring, P‐Sn‐P angles are well below 90° ( cis : 78.25(16)°, 78.89(16)°; trans : 78.65(8)°) while the P exo ‐Sn‐P endo angles are larger ( cis : 96.21(16)° and 97.32(17)°; trans : 100.67(7)°) similar to other cyclic or acyclic P‐E‐P compounds (E=Si: 98.54(3)°–102.46(2)°; E=Sn: 98.78(4)°; E=Pb: 97.84(4)°). In good agreement with the observation of both isomers, the Gibbs free energy difference is small between them (Δ G ( 2 a – 2 b ) =0.9 kcal mol −1 Δ G ( 4 a – 4 b ) =−0.8 kcal mol −1 (ωB97XD/6‐31+G*, 298 K, 1 bar) and these isomers ( 2 and 4 ) are more stable than the corresponding E=E bonded dimeric structures by 25.6 kcal mol −1 (E=Sn) and 28.1 kcal mol −1 (E=Pb).…”

“…Reaction of lithium phosphanide 1 with tetrel dihalides of tin through lead, gave very diverse results. Reaction of SnCl 2 or SnBr 2 with 1 resulted in formation of the dimeric stannylene 2 (Scheme ) which showed characteristic NMR parameters and coupling patterns ( δ ( 119 Sn)=+419 ppm (td, 1 J SnP =1204 Hz, 1 J SnP =735 Hz), ( δ ( 31 P)=−31.4 ppm (P exo ) and −92.6 ppm (P endo )) in agreement with other dimeric phosphanylstannylenes featuring a mutual donor–acceptor motif based on NMR spectroscopy . X‐ray diffraction on several single crystals confirmed the structural motif and revealed the presence of cis and trans isomers (Figure ) which are difficult to distinguish based on heteronuclear NMR in solution, owing to two overlapping sets of signals for both isomers.…”

Stereochemical Alignment in Triphospha[3]ferrocenophanes

“…The recently published bis(silylphosphane) 4 can be easily obtained as mixture of its meso and rac stereoisomers by silylation of 2 6. Bis(silylphosphane) 4 then reacts with the trihalophosphanes PCl 3 and PBr 3 eliminating trimethylsilyl halide at room temperature furnishing [3]ferrocenophanes 3 (Scheme 2).…”