Multinuclear NMR Study and Crystal Structure oftrans-[PtCl2(PHtBu2)2]

Abstract

trans‐[PtCl2(PHtBu2)2] (1) was thoroughly characterised by 1H, 31P{1H} and 195Pt{1H} NMR spectroscopy. Two rotational conformers were found to be stable in solution at room temperature. Force field calculations confirmed that these two conformers are very similar in energy. They co‐crystallise in the tetragonal space group P4bar as revealed by X‐ray diffraction studies. The dynamics of trans‐[PtCl2(PHtBu2)2] is here reported together with spectroscopic evidence of a phosphido‐bridged reduction product.

Synchronized Fluxional Motion and Cyclometalation of Ligands in Platinum(II) Complexes

“…These observations are entirely compatible with hindered rotation around the metal−phosphorus bond. This has been suggested before for the bulky P( o -OMePh) 3 in the parent methoxy complex 4 and for other bulky phosphanes in a variety of square-planar compounds . When the temperature was raised, the signals of the aromatic proton pairs H 3 and H 8 , H 4 and H 7 , and of the substituent methyl groups in the 2 and 9 positions of the phenanthroline showed a definite broadening, indicating a site exchange of the two nitrogen atoms of the dmphen ligand.…”

Synchronized Fluxional Motion and Cyclometalation of Ligands in Platinum(II) Complexes

“…These observations are entirely compatible with hindered rotation around the metal−phosphorus bond. This has been suggested before for the bulky P( o -OMePh) 3 in the parent methoxy complex 4 and for other bulky phosphanes in a variety of square-planar compounds . When the temperature was raised, the signals of the aromatic proton pairs H 3 and H 8 , H 4 and H 7 , and of the substituent methyl groups in the 2 and 9 positions of the phenanthroline showed a definite broadening, indicating a site exchange of the two nitrogen atoms of the dmphen ligand.…”

Steric Control in the Synthesis of Phosphinous Acid-Coordinated Mono- and Binuclear Platinum(II) Complexes

“…After 12 h of reaction (Table , entry 1), the 31 P NMR spectrum of 24 showed two signals with satellites at δ 109.4 and 110.3 ppm (7.7:1 ratio) (Figure ), corresponding to anti ( J Pt−P 2409 Hz) and syn ( J Pt−P 2432 Hz) trans complexes, respectively. This assignment is based on NMR data reported by Mastorilli et al for the platinum complex 29 in equilibrium between syn / anti conformations ( anti / syn = 1.2) (Scheme ). These conformers showed a coupling constant of J Pt−P = 2429 Hz for syn - 29 and J Pt−P = 2421 Hz for anti - 29 .…”

“…Similarly the Pt−P bond length average (2.324 Å) is in agreement with the Pt−P average value (2.320 Å, Figure b) for trans PtCl 2 L 2 . For example, the corresponding values in several complexes containing a trans Cl−Pt−Cl are in the range 2.266 to 2.379 Å and 2.25 to 2.42 Å for trans P−Pt−P. , In platinum square-planar complexes Pt−Cl bond lengths are between 2.276(3) and 2.313(2) Å (Table ) . The slightly larger P(1)−Pt−Cl(2) angles in comparison with P(1)−Pt−Cl(1) angles accommodate an intramolecular hydrogen bonding (O−H···Cl) (Table ).…”

Bridging and Terminal (Phosphanido)platinum Complexes

“…Complex [(PEt 3 )Pt{μ‐P(SiMe 3 ) 2 }] 2 (Pt–Pt) ( 29 ) was obtained by reaction of [PtCl 2 (PEt 3 ) 2 ] with LiP(SiMe 3 ) 2 24. [(PH t Bu 2 )Pt(μ‐P t Bu 2 )] 2 (Pt–Pt) ( 30 ), which is one of the products of Na reduction of trans ‐[PtCl 2 (PH t Bu 2 ) 2 ],37 can be prepared by deprotonation of the corresponding terminal hydride species with n ‐butyllithium 7. Carbonylation of 30 gives [(PH t Bu 2 )Pt(μ‐P t Bu 2 ) 2 Pt(CO)] (Pt–Pt) ( 32 ), which, in turn, reacts (i) with CS 2 to give the product of CO substitution [(PH t Bu 2 )Pt(μ‐P t Bu 2 ) 2 Pt(CS 2 )] (Pt–Pt) ( 33 ),7 (ii) with p ‐tolylisonitrile to give [(L)Pt(μ‐P t Bu 2 ) 2 Pt(CNR)] (Pt–Pt) ( 34a , b ) and, with 3.5 equiv.…”

Synchronized Fluxional Motion and Cyclometalation of Ligands in Platinum(II) Complexes

“…These observations are entirely compatible with hindered rotation around the metal−phosphorus bond. This has been suggested before for the bulky P( o -OMePh) 3 in the parent methoxy complex 4 and for other bulky phosphanes in a variety of square-planar compounds . When the temperature was raised, the signals of the aromatic proton pairs H 3 and H 8 , H 4 and H 7 , and of the substituent methyl groups in the 2 and 9 positions of the phenanthroline showed a definite broadening, indicating a site exchange of the two nitrogen atoms of the dmphen ligand.…”

Steric Control in the Synthesis of Phosphinous Acid-Coordinated Mono- and Binuclear Platinum(II) Complexes

“…After 12 h of reaction (Table , entry 1), the 31 P NMR spectrum of 24 showed two signals with satellites at δ 109.4 and 110.3 ppm (7.7:1 ratio) (Figure ), corresponding to anti ( J Pt−P 2409 Hz) and syn ( J Pt−P 2432 Hz) trans complexes, respectively. This assignment is based on NMR data reported by Mastorilli et al for the platinum complex 29 in equilibrium between syn / anti conformations ( anti / syn = 1.2) (Scheme ). These conformers showed a coupling constant of J Pt−P = 2429 Hz for syn - 29 and J Pt−P = 2421 Hz for anti - 29 .…”

“…Similarly the Pt−P bond length average (2.324 Å) is in agreement with the Pt−P average value (2.320 Å, Figure b) for trans PtCl 2 L 2 . For example, the corresponding values in several complexes containing a trans Cl−Pt−Cl are in the range 2.266 to 2.379 Å and 2.25 to 2.42 Å for trans P−Pt−P. , In platinum square-planar complexes Pt−Cl bond lengths are between 2.276(3) and 2.313(2) Å (Table ) . The slightly larger P(1)−Pt−Cl(2) angles in comparison with P(1)−Pt−Cl(1) angles accommodate an intramolecular hydrogen bonding (O−H···Cl) (Table ).…”

Bridging and Terminal (Phosphanido)platinum Complexes

“…Complex [(PEt 3 )Pt{μ‐P(SiMe 3 ) 2 }] 2 (Pt–Pt) ( 29 ) was obtained by reaction of [PtCl 2 (PEt 3 ) 2 ] with LiP(SiMe 3 ) 2 24. [(PH t Bu 2 )Pt(μ‐P t Bu 2 )] 2 (Pt–Pt) ( 30 ), which is one of the products of Na reduction of trans ‐[PtCl 2 (PH t Bu 2 ) 2 ],37 can be prepared by deprotonation of the corresponding terminal hydride species with n ‐butyllithium 7. Carbonylation of 30 gives [(PH t Bu 2 )Pt(μ‐P t Bu 2 ) 2 Pt(CO)] (Pt–Pt) ( 32 ), which, in turn, reacts (i) with CS 2 to give the product of CO substitution [(PH t Bu 2 )Pt(μ‐P t Bu 2 ) 2 Pt(CS 2 )] (Pt–Pt) ( 33 ),7 (ii) with p ‐tolylisonitrile to give [(L)Pt(μ‐P t Bu 2 ) 2 Pt(CNR)] (Pt–Pt) ( 34a , b ) and, with 3.5 equiv.…”

Synchronized Fluxional Motion and Cyclometalation of Ligands in Platinum(II) Complexes

“…These observations are entirely compatible with hindered rotation around the metal−phosphorus bond. This has been suggested before for the bulky P( o -OMePh) 3 in the parent methoxy complex 4 and for other bulky phosphanes in a variety of square-planar compounds . When the temperature was raised, the signals of the aromatic proton pairs H 3 and H 8 , H 4 and H 7 , and of the substituent methyl groups in the 2 and 9 positions of the phenanthroline showed a definite broadening, indicating a site exchange of the two nitrogen atoms of the dmphen ligand.…”

Steric Control in the Synthesis of Phosphinous Acid-Coordinated Mono- and Binuclear Platinum(II) Complexes

“…After 12 h of reaction (Table , entry 1), the 31 P NMR spectrum of 24 showed two signals with satellites at δ 109.4 and 110.3 ppm (7.7:1 ratio) (Figure ), corresponding to anti ( J Pt−P 2409 Hz) and syn ( J Pt−P 2432 Hz) trans complexes, respectively. This assignment is based on NMR data reported by Mastorilli et al for the platinum complex 29 in equilibrium between syn / anti conformations ( anti / syn = 1.2) (Scheme ). These conformers showed a coupling constant of J Pt−P = 2429 Hz for syn - 29 and J Pt−P = 2421 Hz for anti - 29 .…”

“…Similarly the Pt−P bond length average (2.324 Å) is in agreement with the Pt−P average value (2.320 Å, Figure b) for trans PtCl 2 L 2 . For example, the corresponding values in several complexes containing a trans Cl−Pt−Cl are in the range 2.266 to 2.379 Å and 2.25 to 2.42 Å for trans P−Pt−P. , In platinum square-planar complexes Pt−Cl bond lengths are between 2.276(3) and 2.313(2) Å (Table ) . The slightly larger P(1)−Pt−Cl(2) angles in comparison with P(1)−Pt−Cl(1) angles accommodate an intramolecular hydrogen bonding (O−H···Cl) (Table ).…”

Bridging and Terminal (Phosphanido)platinum Complexes

“…Complex [(PEt 3 )Pt{μ‐P(SiMe 3 ) 2 }] 2 (Pt–Pt) ( 29 ) was obtained by reaction of [PtCl 2 (PEt 3 ) 2 ] with LiP(SiMe 3 ) 2 24. [(PH t Bu 2 )Pt(μ‐P t Bu 2 )] 2 (Pt–Pt) ( 30 ), which is one of the products of Na reduction of trans ‐[PtCl 2 (PH t Bu 2 ) 2 ],37 can be prepared by deprotonation of the corresponding terminal hydride species with n ‐butyllithium 7. Carbonylation of 30 gives [(PH t Bu 2 )Pt(μ‐P t Bu 2 ) 2 Pt(CO)] (Pt–Pt) ( 32 ), which, in turn, reacts (i) with CS 2 to give the product of CO substitution [(PH t Bu 2 )Pt(μ‐P t Bu 2 ) 2 Pt(CS 2 )] (Pt–Pt) ( 33 ),7 (ii) with p ‐tolylisonitrile to give [(L)Pt(μ‐P t Bu 2 ) 2 Pt(CNR)] (Pt–Pt) ( 34a , b ) and, with 3.5 equiv.…”