Tolerant to air σ-alkane complexes by surface modification of single crystalline solid-state molecular organometallics using vapour-phase cationic polymerisation: SMOM@polymer

Abstract

Surface-initiated cationic polymerisation of ethylvinylether at single-crystals of the σ-alkane complex [Rh(Cy2PCH2CH2PCy2)(NBA)][BArF4] imparts air-tolerance to this highly reactive complex.

A Series of Crystallographically Characterized Linear and Branched σ-Alkane Complexes of Rhodium: From Propane to 3-Methylpentane

“…The C–C distances in the hydrocarbon are consistent with single bonds, and the Rh···C distances are ∼0.2 Å longer than in the starting propene complex ( Table 1 ). 39 The propane binds in a 1,3-motif: Rh···C 2.46(2), 2.45(2) Å (calculated 2.50 and 2.51 Å, section 2.3 ), and the central carbon (C2) is considerably farther away, being nonbonding (Rh···C2 2.99(3) Å), further signaling a change from the π-bound propene complex. Given the quality of the data, we cannot rule out that the propane binds slightly asymmetrically, as suggested by the DFT-calculated distances.…”

“…The addition of H 2 to the propene complex [Rh­(Cy 2 PCH 2 CH 2 PCy 2 )­(η 2 π :η 2 C–H -H 2 CCHCH 3 )]­[BAr F 4 ] ( [1-propene]­[BAr F 4 ] ) , was studied on selected single crystals in situ on the I19 Beamline. H 2 was added while the sample was being cooled from 298 to 150 K. This allowed for rapid initial reaction with H 2 and also slowed decomposition of the alkane complex, once formed.…”

“…) 25,39 was studied on selected single crystals in situ on the I19 Beamline. H 2 was added while the sample was being cooled from 298 to 150 K. This allowed for rapid initial reaction with H 2 and also slowed decomposition of the alkane complex, once formed.…”

“…The C−C distances in the hydrocarbon are consistent with single bonds, and the Rh•••C distances are ∼0.2 Å longer than in the starting propene complex (Table 1). 39 The propane binds in a 1,3-motif: Rh ), which have 1,2-and 1,3-alkane binding motifs, respectively. They are considerably shorter than for d 6 -propane weakly bound to an open Fe site in the MOF Fe 2 (dobdc) (∼3 Å), as analyzed by powder neutron diffraction at 4 K. 41 The 1,3-motif is similar to that proposed for propane coordination to a PdO(101) surface, albeit spanning two Pd sites.…”

Inverse Isotope Effects in Single-Crystal to Single-Crystal Reactivity and the Isolation of a Rhodium Cyclooctane σ-Alkane Complex

“…As this change occurs at the same point in time for both H 2 and D 2 addition, we suggest this is not an experimental artifact and is triggered at a certain conversion of [1-COD][BAr F 4 ] . As the microcracking of single crystals 45 would be expected to increase the rate of conversion through surface area arguments, we speculate that this change has to do with a correlated, 46 but subtle, change in the spatially averaged periodic structure that occurs in the hydrogenation of [1-COD][BAr F 4 ] . The repetition of these experiments on larger single crystals and the measurement of the unit cell parameters with time showed no significant step change in axes lengths that would signal a phase change.…”