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Formation of Diphenylphosphanylbutadienyl Complexes by Insertion of Two P‐Coordinated Alkynylphosphanes into a PtC 6 F 5 Bond: Detection of Intermediate and Reaction Products
Author(s) -
Ara Irene,
Forniés Juan,
García Ana,
Gómez Julio,
Lalinde Elena,
Moreno M. Teresa
Publication year - 2002
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20020816)8:16<3698::aid-chem3698>3.0.co;2-0
Subject(s) - chemistry , synthon , ligand (biochemistry) , stereochemistry , medicinal chemistry , molecule , platinum , nuclear magnetic resonance spectroscopy , crystallography , catalysis , organic chemistry , biochemistry , receptor
The reactions between cis ‐[M(C 6 F 5 ) 2 (PPh 2 CCR) 2 ] (M=Pt, Pd; R=Ph, t Bu, Tol 2, 3 ) or cis ‐[Pt(C 6 F 5 ) 2 (PPh 2 CCR)(PPh 2 CC t Bu)] (R=Ph 4 , Tol 5 ) and cis ‐[Pt(C 6 F 5 ) 2 (thf) 2 ] 1 have been investigated. Whereas [M](PPh 2 CC t Bu) 2 ([M]= cis ‐M(C 6 F 5 ) 2 ) is inert towards 1 , the analogous reactions starting from [M](PPh 2 CCR) 2 or [Pt](PPh 2 CCR)(PPh 2 CC t Bu) (R=Ph, Tol) afford unusual binuclear species [Pt(C 6 F 5 )(S) μ ‐{C(R′)C(PPh 2 )C(PPh 2 )C(R)(C 6 F 5 )}M(C 6 F 5 ) 2 ] (R=R′=Ph, Tol, M=Pt 6 a , c , M=Pd 7 a , c ; M=Pt, R′= t Bu, R=Ph 8 , Tol 9 ) containing a bis(diphenylphosphanyl)butadienyl bridging ligand formed by an unprecedented sequential insertion reaction of two P‐coordinated PPh 2 CCR ligands into a PtC 6 F 5 bond. Although in solution the presence of coordinated solvent S (S=(thf) x (H 2 O) y ) in 6, 7 is suggested by NMR spectroscopy, X‐ray diffraction analyses of different crystals of the mixed complex [Pt(C 6 F 5 ) μ ‐{C( t Bu)C(PPh 2 )C(PPh 2 )C(Tol)(C 6 F 5 )}Pt(C 6 F 5 ) 2 ] 9 unequivocally establish that in the solid state the steric crowding of the new diphenylbutadienyl ligand formed stabilizes an unusual coordinatively unsaturated T‐shaped 3‐coordinated platinum( II ) center. Structure determinations of the mononuclear precursors cis ‐[Pt(C 6 F 5 ) 2 (PPh 2 CCR) 2 ] (R=Ph, t Bu, Tol) have been carried out to evaluate the factors affecting the insertion processes. The reactions of the platinum complexes 6 towards neutral ligands (L=CO, py, PPh 2 H, CN t Bu) in a 1:1 molar ratio afford related diplatinum derivatives 10 – 13 , whereas treatment with CN t Bu (1:2 molar ratio) or 2,2′‐bipy (1:1 molar ratio) results in the opening of the chelating ring to give cis , cis ‐[Pt(C 6 F 5 )(L) 2 μ ‐{1‐ κC 1 :2‐ κPP ′‐C(R)C(PPh 2 )C(PPh 2 )C(R)(C 6 F 5 )}Pt(C 6 F 5 ) 2 ] ( 14, 15 ). The unsaturated or solvento complexes are unstable in solution evolving firstly, through an unexpected formal 4‐1 R (Ph, Tol) migration, to the intermediate diphosphanylbutadienyl isomer derivatives [Pt(C 6 F 5 )(S) μ ‐{C(C 6 F 5 )C(PPh 2 )C(PPh 2 )C(R) 2 }M(C 6 F 5 ) 2 ] ( 16, 18 ) (X‐ray, R=Ph, M=Pt) and, finally, to 1‐pentafluorophenyl‐2,3‐bis(diphenylphosphanyl)naphthalene mononuclear complexes ( 17, 19 ) by annulation of a phenyl or tolyl group.