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Six-membered cyclometallated derivatives of platinum(II) derived from 2-benzylpyridines: crystal and molecular structure of [Pt(L)(Ph3P)Cl] (HL = 2-(1-methylbenzyl)pyridine)

Minghetti, Giovanni and Zucca, Antonio and Stoccoro, Sergio and Cinellu, Maria Agostina and Manassero, Mario and Sansoni, Mirella (1994) Six-membered cyclometallated derivatives of platinum(II) derived from 2-benzylpyridines: crystal and molecular structure of [Pt(L)(Ph3P)Cl] (HL = 2-(1-methylbenzyl)pyridine). Journal of Organometallic Chemistry, Vol. 481 (2), p. 195-204. ISSN 0022-328X. Article.

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DOI: 10.1016/0022-328X(94)85026-7

Abstract

The reaction of K2[PtCl4] with 2-(1-methylbenzyl)pyridine, HL, and 2-benzylpyridine, HL', affords the cyclometallated species [{Pt(L)Cl}2] (1) and [{Pt(L')Cl}2] (2), respectively. The chloride bridge in complex 1 can be split by neutral or anionic species to give the monomeric, [Pt(L)(Ph3P)Cl], as two isomers, trans-P-Pt-C (3) and trans-P-Pt-N, (4), [Pt(L)(py)Cl] (5), [Pt(L)(CO)Cl] (6), [Pt(L)(CNCH2SO2C6H4CH3-4)Cl] (7), [Pt(L)(acac)] (Hacac = 2,4-pentanedione) (8), [Pt(L)(dppm)][BF4] (dppm = bis(diphenyl-phosphino)methane) (9), [Pt(L)(dppe)][BF4] (dppe = bis(diphenylphosphino)ethane) (10) and [Pt(L)(dipy)][BF4](dipy = 2,2'-dipyridine) (11). Similarly, compound 2, by reaction with Ph3P, affords [Pt(L')(Ph3P)Cl], as two isomers, trans-P-Pt-C (12) and trans-P-Pt-N (13). Reaction of compounds 1 or 4 with AgBF4 in acetonitrile affords [Pt(L)(CH3CN)2IBF4] (14) or [Pt(L)(Ph3P)-(CH3CN)][BF4] (15). From these, [Pt(L)(Ph3P)2][BF4] (16), [Pt(L)(Ph3P)(CO)][BF4] (17) and [Pt(L)(Ph3P)(py)][BF4] (18), can be obtained by displacement of the coordinated acetonitrile. The new complexes were characterized by IR, 1H and 31P NMR and FAB-MS spectroscopic techniques. The NMR spectra at room temperature of most of the species derived from HL give evidence for the presence in solution of two diastereomers a and b. The structure of one diastereomer of complex 4 has been solved by single crystal X-ray diffraction, 4b. The platinum atom is in an almost square planar geometry with a P-Pt-N trans arrangement: Pt-N = 2.095(3), Pt-C = 1.998(4), Pt-P = 2.226(1) and Pt-Cl = 2.400(1) Å. The six-membered cyclometallated ring is in a boat conformation, with the CH3 group in an equatorial position, i.e pointing away from the metal. Attempts to obtain [{Pt(L″)Cl}2] (HL″ = 2-(dimethylbenzyl)pyridine), afforded an insoluble product heavily contaminated by platinum metal; treatment of this crude material with Ph3P gave [Pt(L″)(Ph3P)Cl] (19).

Item Type:Article
ID Code:4915
Status:Published
Refereed:Yes
Uncontrolled Keywords:Platinum, cyclometallation, X-ray structure
Subjects:Area 03 - Scienze chimiche > CHIM/03 Chimica generale e inorganica
Divisions:001 Università di Sassari > 01 Dipartimenti > Chimica
Publisher:Elsevier Science
ISSN:0022-328X
Deposited On:22 Nov 2010 15:36

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