Solution and Solid-State Properties of Luminescent M−M Bond-Containing Coordination/Organometallic Polymers Using the RNC-M₂(dppm)₂-CNR Building Blocks (M = Pd, Pt; R = Aryl, Alkyl)

Abstract

Two families of organometallic polymers built upon the bimetallic M2(dppm)2L(2)2+ fragments (M = Pd, Pt; dppm = bis(diphenylphosphino)methane, L = 1,4-diisocyano-2,3,5,6-tetramethylbenzene (diiso), 1,8-diisocyano-p-menthane (dmb), 1-isocyano-2,6-dimethylbenzene, 1-isocyano-4-isopropylbenzene, and tert-butylisocyanide) were synthesized and fully characterized (1H and 31P NMR, X-ray crystallography (model compounds), IR, Raman, chem. anal., TGA, DSC, powder XRD, 31P NMR T1 and NOE, light scattering, and conductivity measurements). Evidence for polymers in the solid state is provided from the swelling of the polymers upon dissolution and the formation of stand-alone films. However, these species become small oligomers when dissolved. The materials are luminescent in the solid state at 298 and 77 K and in PrCN solution at 77 K. These emissions result from triplet 3(d sigma d sigma*) states despite the presence of low-lying pi-pi* MO levels according to DFT calculations for the aryl isocyanide model compounds. The emission band maxima are located between 640 and 750 nm and exhibit lifetimes of 3-6 ns for the Pd species and 3-4 micros for the Pt analogues in PrCN solution at 77 K. No evidence of intramolecular excitonic photoprocesses was found in any of the polymers.

Tandem β‐Boration/Arylation of α,β‐Unsaturated Carbonyl Compounds by Using a Single Palladium Complex To Catalyse Both Steps

“…Compounds with the [Pd 2 A C H T U N G T R E N N U N G (dppm) 2 ] 2 + skeleton have F values between 33 and 50.58. [14,15] The Pd-Pd distance is 2.5459(8) , which is smaller than the corresponding distance in [Pd 2 X 2 A C H T U N G T R E N N U N G (dppm) 2 ] compounds (2.594-2.699 ) and may indicate that acetonitrile has a weaker trans effect. [14] The (12) .…”

“…[14] The (12) . [15] Compound 3 crystallises in the monoclinic space group P2 1 /n. Each palladium atom is coordinated by one nitrogen atom and one phosphorus atom, each from a different C 9 H 7 NPPh 2 À ligand, and two different carboxylate anions complete the square-planar coordination.…”

“…The substrate (E)-isobutyl but-2-enoate, with a bulkier ester moiety, was also efficiently b-borated with catalytic system 3, but less so with 4, 7, and 8 (Table 3, entries 9-13), even after longer reaction times. A similar trend was observed when a-substituted a,b-unsaturated esters were used in the reaction, in that while (E)-methyl 2-methylbut-2-enoate was conveniently transformed into the b-organoborated product with catalytic system 3 ( Table 3, entry 14), the analogous substrates (E)-ethyl 2-methylbut-2-enoate and (Z)-isobutyl 2-methylbut-2-enoate were only b-borated with low or moderate conversions, even after reaction times of 16 or 24 h (Table 3, entries [15][16][17][18][19]. Therefore, the nature of the ester moiety seems to play an important role in the b-boration reaction as far as the substrate is concerned, and catalytic system 3 seems to be the most efficient, probably because it contains only two P,N ligands.…”

The Spectroscopy and Photophysical Behavior of Diphosphine- and Diisocyanide-Containing Coordination and Organometallic Oligomers and Polymers: Focus on Palladium and Platinum, Copper, Silver, and Gold

“…The investigations of the model compounds 23 and 24 and the polymers 25 and 26 provided the first clear evidence for inter-unit interactions [24]. Whereas all previous model compounds and polymers discussed in this chapter showed very little clear-cut evidence for inter-unit interactions based on the comparison between band shift and FWHM within the model compounds and the polymers, where (at best) several ~20-nm shifts (in one case), were observed, 23-26 show otherwise.…”

The First P‐Stereogenic 1D Coordination Polymers with the Metal Centers in the Backbone

“…[29] The second major thermal event occurs between 260 and 450°C and is most likely due to decomposition of the dppm* ligand mixed with the loss of the BF 4 anions. All in all, these new materials exhibit a very strong resemblance with thermal behavior observed for the aforementioned polymers.…”