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Article: Carbene and Isocyanide Ligation at Luminescent Cyclometalated 6-Phenyl-2,2′-bipyridyl Platinum(II) Complexes: Structural and Spectroscopic Studies

TitleCarbene and Isocyanide Ligation at Luminescent Cyclometalated 6-Phenyl-2,2′-bipyridyl Platinum(II) Complexes: Structural and Spectroscopic Studies
Authors
Issue Date1999
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/organometallics
Citation
Organometallics, 1999, v. 18 n. 17, p. 3327-3336 How to Cite?
AbstractA series of luminescent cyclometalated platinum(II) diamino-carbene complexes, namely, [(CNN)Pt{C(NHR1)(NHR2)}]+ (HCNN = 6-phenyl-2,2′-bipyridine; for R1 = tBu, R2 = Me (2), NH2 (3), CH2Ph (4); for R1 = 2,6-Me2C6H3 (Ar′), R2 = Me (6), NH2 (7), CH2Ph (8)), are synthesized by nucleophilic attack of amines at the coordinated isocyanide ligands of [(CNN)-PtC≡NR1]+ (R1 = tBu (1), Ar′ (5)). The binuclear bridging bis(carbene) derivative [{(CNN)Pt}2μ-{C(NHtBu)(NH(CH2) 3)}2NMe]2+ (9) is prepared by treatment of 1 with excess 3,3′-diamino-N-methyldipropylamine. The molecular structures of 2(ClO4)•0.5H2O, 3(ClO4)• 0.5H2O, 4(ClO4), and 6(ClO4) reveal Pt-C(carbene) distances of 1.997(7), 1.992(4), 1.989(6), and 1.996(8) Å, respectively. Short N-C(carbene) bond lengths (mean 1.332 Å) imply substantial pπ-pπ interactions within the N-C(carbene)-N fragment, and minimal π bonding in the Pt-C(carbene) moiety is inferred. Weak π-π stacking interactions between the CNN ligands are observed in the crystal lattice of 2-4 and 6 (range 3.5-3.6 Å). Complexes 1-9 display structureless emissions, with λmax ranging from 528 to 558 nm in acetonitrile at 298 K, and they are assigned to 3MLCT excited states. The emissions of 1 and 5 exhibit noticeably higher quantum yields, which reflect the strong ligand field strength of the isocyanide auxiliaries. The 77 K emissions of 1-9 in frozen acetonitrile are blue-shifted and display well-resolved vibronic structures. At high concentrations (≥10-5 M), 1 and 5 show an additional low-energy band at 627 (in butyronitrile) and 730 nm which are ascribed to π-π excimeric and MMLCT emissions, respectively. The solid-state emissions of complexes 1(ClO4)-9(ClO4)2 (except 5(ClO4)) at 298 K are red-shifted from solution to λmax 553-579 nm with a shoulder at 595-612 nm. They are tentatively assigned to 3MLCT excited states with excimeric character due to weak CNN π-π interactions, as evident in the crystal structures. The remarkable low-energy luminescence of 5(ClO4) in the solid state (λmax 704 nm at 298 K; 781 nm at 77 K) is attributed to MMLCT transitions arising from solid-state intermolecular stacking interactions. Upon photolysis with UV-visible light, reaction between complex 2 and iodomethane in acetonitrile leads to decomposition of the diamino-carbene ligand and generation of the platinum(IV) diiodide cyanide derivative trans-[(CNN)-Pt(C≡N)I2] (10).
Persistent Identifierhttp://hdl.handle.net/10722/167303
ISSN
2015 Impact Factor: 4.186
2015 SCImago Journal Rankings: 2.043
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorLai, SWen_HK
dc.contributor.authorChan, MCWen_HK
dc.contributor.authorCheung, KKen_HK
dc.contributor.authorChe, CMen_HK
dc.date.accessioned2012-10-08T03:05:27Z-
dc.date.available2012-10-08T03:05:27Z-
dc.date.issued1999en_HK
dc.identifier.citationOrganometallics, 1999, v. 18 n. 17, p. 3327-3336en_HK
dc.identifier.issn0276-7333en_HK
dc.identifier.urihttp://hdl.handle.net/10722/167303-
dc.description.abstractA series of luminescent cyclometalated platinum(II) diamino-carbene complexes, namely, [(CNN)Pt{C(NHR1)(NHR2)}]+ (HCNN = 6-phenyl-2,2′-bipyridine; for R1 = tBu, R2 = Me (2), NH2 (3), CH2Ph (4); for R1 = 2,6-Me2C6H3 (Ar′), R2 = Me (6), NH2 (7), CH2Ph (8)), are synthesized by nucleophilic attack of amines at the coordinated isocyanide ligands of [(CNN)-PtC≡NR1]+ (R1 = tBu (1), Ar′ (5)). The binuclear bridging bis(carbene) derivative [{(CNN)Pt}2μ-{C(NHtBu)(NH(CH2) 3)}2NMe]2+ (9) is prepared by treatment of 1 with excess 3,3′-diamino-N-methyldipropylamine. The molecular structures of 2(ClO4)•0.5H2O, 3(ClO4)• 0.5H2O, 4(ClO4), and 6(ClO4) reveal Pt-C(carbene) distances of 1.997(7), 1.992(4), 1.989(6), and 1.996(8) Å, respectively. Short N-C(carbene) bond lengths (mean 1.332 Å) imply substantial pπ-pπ interactions within the N-C(carbene)-N fragment, and minimal π bonding in the Pt-C(carbene) moiety is inferred. Weak π-π stacking interactions between the CNN ligands are observed in the crystal lattice of 2-4 and 6 (range 3.5-3.6 Å). Complexes 1-9 display structureless emissions, with λmax ranging from 528 to 558 nm in acetonitrile at 298 K, and they are assigned to 3MLCT excited states. The emissions of 1 and 5 exhibit noticeably higher quantum yields, which reflect the strong ligand field strength of the isocyanide auxiliaries. The 77 K emissions of 1-9 in frozen acetonitrile are blue-shifted and display well-resolved vibronic structures. At high concentrations (≥10-5 M), 1 and 5 show an additional low-energy band at 627 (in butyronitrile) and 730 nm which are ascribed to π-π excimeric and MMLCT emissions, respectively. The solid-state emissions of complexes 1(ClO4)-9(ClO4)2 (except 5(ClO4)) at 298 K are red-shifted from solution to λmax 553-579 nm with a shoulder at 595-612 nm. They are tentatively assigned to 3MLCT excited states with excimeric character due to weak CNN π-π interactions, as evident in the crystal structures. The remarkable low-energy luminescence of 5(ClO4) in the solid state (λmax 704 nm at 298 K; 781 nm at 77 K) is attributed to MMLCT transitions arising from solid-state intermolecular stacking interactions. Upon photolysis with UV-visible light, reaction between complex 2 and iodomethane in acetonitrile leads to decomposition of the diamino-carbene ligand and generation of the platinum(IV) diiodide cyanide derivative trans-[(CNN)-Pt(C≡N)I2] (10).en_HK
dc.languageengen_US
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/organometallicsen_HK
dc.relation.ispartofOrganometallicsen_HK
dc.titleCarbene and Isocyanide Ligation at Luminescent Cyclometalated 6-Phenyl-2,2′-bipyridyl Platinum(II) Complexes: Structural and Spectroscopic Studiesen_HK
dc.typeArticleen_HK
dc.identifier.emailLai, SW: swlai@hku.hken_HK
dc.identifier.emailChe, CM: cmche@hku.hken_HK
dc.identifier.authorityLai, SW=rp00717en_HK
dc.identifier.authorityChe, CM=rp00670en_HK
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1021/om990256h-
dc.identifier.scopuseid_2-s2.0-0000818691en_HK
dc.identifier.hkuros51125-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0000818691&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume18en_HK
dc.identifier.issue17en_HK
dc.identifier.spage3327en_HK
dc.identifier.epage3336en_HK
dc.identifier.isiWOS:000082249400012-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridLai, SW=7402937200en_HK
dc.identifier.scopusauthoridChan, MCW=7402598116en_HK
dc.identifier.scopusauthoridCheung, KK=7402406613en_HK
dc.identifier.scopusauthoridChe, CM=7102442791en_HK

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