(Phosphido)platinum Complexes by Sodium-Promoted Reaction ofcis-PtCl2(PHCy2)2 − Synthesis and Crystal Structure of [trans-Pt(PCy2H)2(PCy2)Cl], a Rare Example of a Terminal (Phosphido)platinum(II) Complex

Abstract

cis‐PtCl2(PHCy2)2 (1) reacts at 0 °C in toluene with sodium metal to give the dinuclear PtI complexes cis‐[(PHCy2)(H)Pt(μ‐PCy2)]2 (2) and [(PHCy2)(Cl)Pt(μ‐PCy2)Pt(PHCy2)2](Pt−Pt) (3). On standing in solution, complex 3 isomerizes to trans‐[(PHCy2)(Cl)Pt(μ‐PCy2)2Pt(PHCy2)(H)] (4). When treated with sodium at room temperature, complex 3 transforms into [Pt(μ‐PCy2)(PHCy2)]2(Pt−Pt) (5). The sodium reduction of 1 carried out at room temperature leads to the direct formation of the phosphido bridged dinuclear complex [Pt(μ‐PCy2)(PHCy2)]2(Pt−Pt) (5) along with the mononuclear platinum(II) complex [trans‐Pt(PCy2H)2(PCy2)Cl] (6). Complex 6, which has also been obtained by reaction of 1 with LiPCy2, unambiguously shows by single‐crystal X‐ray diffraction the presence of a pyramidal terminal phosphido ligand. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Reactivity of a Phosphinito-Bridged PtI−PtI Complex with Nucleophiles: Substitution versus Addition

“…The addition of one equivalent of PHCy 2 to a toluene solution of 1 caused its transformation, after 3 h at 50 °C, into the symmetric Pt I dimer [(PHCy 2 )Pt(μ-PCy 2 )] 2 ( Pt − Pt ) ( 2 ) with contemporary elimination of P(O)HCy 2 . Complex 2 was previously obtained by us, and its spectroscopic features have been discussed elsewhere . Here it is sufficient to note that substitution of the phosphinito bridge with a phosphido bridge caused the expected strong deshielding in the 31 P NMR signal of μ-PCy 2 (from δ 137 in 1 to δ 242 in 2 ) due to the presence of two phosphides bridging two Pt atoms linked by a single bond …”

“…In particular, all of the signals in the 31 P{ 1 H} NMR spectrum of the mixture after reaction [which contained an excess of P(O)HCy 2 ] were very broad except for that of the bridging phosphide. The broadness of the free P(O)HCy 2 signal was due to an exchange process involving formation and rupture of the hydrogen bonds between free P(O)HCy 2 and coordinated P(O)Cy 2 in the adducts of 4 with free P(O)HCy 2 ; the broadness of the signals from the coordinated P(O)Cy 2 and PHCy 2 ligands had to be attributed to hindered rotation about the Pt−P bonds. , Exchange between free P(O)HCy 2 and coordinated P(O)Cy 2 could be ruled out on the basis of the relative sharpness of the phosphide signal along with the absence of cross-peaks in 31 P{ 1 H} and 1 H EXSY experiments…”

Reactivity of a Phosphinito-Bridged PtI−PtI Complex with Nucleophiles: Substitution versus Addition

“…The addition of one equivalent of PHCy 2 to a toluene solution of 1 caused its transformation, after 3 h at 50 °C, into the symmetric Pt I dimer [(PHCy 2 )Pt(μ-PCy 2 )] 2 ( Pt − Pt ) ( 2 ) with contemporary elimination of P(O)HCy 2 . Complex 2 was previously obtained by us, and its spectroscopic features have been discussed elsewhere . Here it is sufficient to note that substitution of the phosphinito bridge with a phosphido bridge caused the expected strong deshielding in the 31 P NMR signal of μ-PCy 2 (from δ 137 in 1 to δ 242 in 2 ) due to the presence of two phosphides bridging two Pt atoms linked by a single bond …”

“…In particular, all of the signals in the 31 P{ 1 H} NMR spectrum of the mixture after reaction [which contained an excess of P(O)HCy 2 ] were very broad except for that of the bridging phosphide. The broadness of the free P(O)HCy 2 signal was due to an exchange process involving formation and rupture of the hydrogen bonds between free P(O)HCy 2 and coordinated P(O)Cy 2 in the adducts of 4 with free P(O)HCy 2 ; the broadness of the signals from the coordinated P(O)Cy 2 and PHCy 2 ligands had to be attributed to hindered rotation about the Pt−P bonds. , Exchange between free P(O)HCy 2 and coordinated P(O)Cy 2 could be ruled out on the basis of the relative sharpness of the phosphide signal along with the absence of cross-peaks in 31 P{ 1 H} and 1 H EXSY experiments…”

Multinuclear and Dynamic NMR Study of trans-[Pt(Cl)(PHCy2)2(PCy2)], [Pt(Cl)(PHCy2)3][BF4], [Pt(Cl)(PHCy2)3][Cl], trans-[Pt(Cl)(PHCy2)2{P(S)Cy2}], and trans-[Pt(Cl)(PHCy2)2{P(O)Cy2}]. Influence of Intramolecular PO···H−P and Cl···H−P Interactions on Restricted Rotation about Pt−P Bond. X-ray Structure of trans-[Pt(Cl)(PHCy2

“…We believe that the rotamer stable at low temperatures is the sterically least hindered conformer depicted in Figure and found in the crystal 3 PLUTON 28 view of the rotamer found in the crystal of 1 . …”

“…As for the electronic effects that affect the inversion barrier, our crystallographic and 31 P NMR results 10 point out a low s character of the P X -Pt bond in 1 which should lead to a high inversion barrier because of the rehybridization energy necessary to reach the sp 2 transition state. 26 Taking the 31 P X -195 Pt coupling constant as a probe of the s character of the P X -Pt bond (the lower the constant, the lower the s character) 5 and the 1102-1112 Hz 1 J 31 P X -195 Pt value found for cyclometalated dimesityl phosphide Pt(II) complexes (for which pure inversion barriers of ca.…”

Synthesis and Structure of P-Halogenated Benzazaphospholes and Their Reactivity toward Pt(0) Sources

“…Using MestreNova, simulated 31 P NMR signals of 4–I that closely fit the experimental spectrum were produced and are shown in Figure . Additional 31 P NMR signals due to the doubly labeled isotopologue (two 195 Pt nuclei), which have been previously observed in related Pt­(I)–Pt­(I) dimers , and should statistically compose approximately one-ninth of the product, were not observed, even on the 600 MHz NMR spectrometer (242 MHz for 31 P nuclei). Although featuring slightly different 1 J Pt–P , 2 J PP , and 3 J PP values, the 31 P­{ 1 H} NMR spectrum of 4–Br mirrored what was observed with 4–I .…”

Reactivity of a Phosphinito-Bridged PtI−PtI Complex with Nucleophiles: Substitution versus Addition

“…The addition of one equivalent of PHCy 2 to a toluene solution of 1 caused its transformation, after 3 h at 50 °C, into the symmetric Pt I dimer [(PHCy 2 )Pt(μ-PCy 2 )] 2 ( Pt − Pt ) ( 2 ) with contemporary elimination of P(O)HCy 2 . Complex 2 was previously obtained by us, and its spectroscopic features have been discussed elsewhere . Here it is sufficient to note that substitution of the phosphinito bridge with a phosphido bridge caused the expected strong deshielding in the 31 P NMR signal of μ-PCy 2 (from δ 137 in 1 to δ 242 in 2 ) due to the presence of two phosphides bridging two Pt atoms linked by a single bond …”

“…In particular, all of the signals in the 31 P{ 1 H} NMR spectrum of the mixture after reaction [which contained an excess of P(O)HCy 2 ] were very broad except for that of the bridging phosphide. The broadness of the free P(O)HCy 2 signal was due to an exchange process involving formation and rupture of the hydrogen bonds between free P(O)HCy 2 and coordinated P(O)Cy 2 in the adducts of 4 with free P(O)HCy 2 ; the broadness of the signals from the coordinated P(O)Cy 2 and PHCy 2 ligands had to be attributed to hindered rotation about the Pt−P bonds. , Exchange between free P(O)HCy 2 and coordinated P(O)Cy 2 could be ruled out on the basis of the relative sharpness of the phosphide signal along with the absence of cross-peaks in 31 P{ 1 H} and 1 H EXSY experiments…”

Multinuclear and Dynamic NMR Study of trans-[Pt(Cl)(PHCy2)2(PCy2)], [Pt(Cl)(PHCy2)3][BF4], [Pt(Cl)(PHCy2)3][Cl], trans-[Pt(Cl)(PHCy2)2{P(S)Cy2}], and trans-[Pt(Cl)(PHCy2)2{P(O)Cy2}]. Influence of Intramolecular PO···H−P and Cl···H−P Interactions on Restricted Rotation about Pt−P Bond. X-ray Structure of trans-[Pt(Cl)(PHCy2

“…We believe that the rotamer stable at low temperatures is the sterically least hindered conformer depicted in Figure and found in the crystal 3 PLUTON 28 view of the rotamer found in the crystal of 1 . …”

“…As for the electronic effects that affect the inversion barrier, our crystallographic and 31 P NMR results 10 point out a low s character of the P X -Pt bond in 1 which should lead to a high inversion barrier because of the rehybridization energy necessary to reach the sp 2 transition state. 26 Taking the 31 P X -195 Pt coupling constant as a probe of the s character of the P X -Pt bond (the lower the constant, the lower the s character) 5 and the 1102-1112 Hz 1 J 31 P X -195 Pt value found for cyclometalated dimesityl phosphide Pt(II) complexes (for which pure inversion barriers of ca.…”

Synthesis and Structure of P-Halogenated Benzazaphospholes and Their Reactivity toward Pt(0) Sources

“…Using MestreNova, simulated 31 P NMR signals of 4–I that closely fit the experimental spectrum were produced and are shown in Figure . Additional 31 P NMR signals due to the doubly labeled isotopologue (two 195 Pt nuclei), which have been previously observed in related Pt­(I)–Pt­(I) dimers , and should statistically compose approximately one-ninth of the product, were not observed, even on the 600 MHz NMR spectrometer (242 MHz for 31 P nuclei). Although featuring slightly different 1 J Pt–P , 2 J PP , and 3 J PP values, the 31 P­{ 1 H} NMR spectrum of 4–Br mirrored what was observed with 4–I .…”

Reactivity of a Phosphinito-Bridged PtI−PtI Complex with Nucleophiles: Substitution versus Addition

“…The addition of one equivalent of PHCy 2 to a toluene solution of 1 caused its transformation, after 3 h at 50 °C, into the symmetric Pt I dimer [(PHCy 2 )Pt(μ-PCy 2 )] 2 ( Pt − Pt ) ( 2 ) with contemporary elimination of P(O)HCy 2 . Complex 2 was previously obtained by us, and its spectroscopic features have been discussed elsewhere . Here it is sufficient to note that substitution of the phosphinito bridge with a phosphido bridge caused the expected strong deshielding in the 31 P NMR signal of μ-PCy 2 (from δ 137 in 1 to δ 242 in 2 ) due to the presence of two phosphides bridging two Pt atoms linked by a single bond …”

“…In particular, all of the signals in the 31 P{ 1 H} NMR spectrum of the mixture after reaction [which contained an excess of P(O)HCy 2 ] were very broad except for that of the bridging phosphide. The broadness of the free P(O)HCy 2 signal was due to an exchange process involving formation and rupture of the hydrogen bonds between free P(O)HCy 2 and coordinated P(O)Cy 2 in the adducts of 4 with free P(O)HCy 2 ; the broadness of the signals from the coordinated P(O)Cy 2 and PHCy 2 ligands had to be attributed to hindered rotation about the Pt−P bonds. , Exchange between free P(O)HCy 2 and coordinated P(O)Cy 2 could be ruled out on the basis of the relative sharpness of the phosphide signal along with the absence of cross-peaks in 31 P{ 1 H} and 1 H EXSY experiments…”

Multinuclear and Dynamic NMR Study of trans-[Pt(Cl)(PHCy2)2(PCy2)], [Pt(Cl)(PHCy2)3][BF4], [Pt(Cl)(PHCy2)3][Cl], trans-[Pt(Cl)(PHCy2)2{P(S)Cy2}], and trans-[Pt(Cl)(PHCy2)2{P(O)Cy2}]. Influence of Intramolecular PO···H−P and Cl···H−P Interactions on Restricted Rotation about Pt−P Bond. X-ray Structure of trans-[Pt(Cl)(PHCy2

“…We believe that the rotamer stable at low temperatures is the sterically least hindered conformer depicted in Figure and found in the crystal 3 PLUTON 28 view of the rotamer found in the crystal of 1 . …”

“…As for the electronic effects that affect the inversion barrier, our crystallographic and 31 P NMR results 10 point out a low s character of the P X -Pt bond in 1 which should lead to a high inversion barrier because of the rehybridization energy necessary to reach the sp 2 transition state. 26 Taking the 31 P X -195 Pt coupling constant as a probe of the s character of the P X -Pt bond (the lower the constant, the lower the s character) 5 and the 1102-1112 Hz 1 J 31 P X -195 Pt value found for cyclometalated dimesityl phosphide Pt(II) complexes (for which pure inversion barriers of ca.…”

Synthesis and Structure of P-Halogenated Benzazaphospholes and Their Reactivity toward Pt(0) Sources

“…Using MestreNova, simulated 31 P NMR signals of 4–I that closely fit the experimental spectrum were produced and are shown in Figure . Additional 31 P NMR signals due to the doubly labeled isotopologue (two 195 Pt nuclei), which have been previously observed in related Pt­(I)–Pt­(I) dimers , and should statistically compose approximately one-ninth of the product, were not observed, even on the 600 MHz NMR spectrometer (242 MHz for 31 P nuclei). Although featuring slightly different 1 J Pt–P , 2 J PP , and 3 J PP values, the 31 P­{ 1 H} NMR spectrum of 4–Br mirrored what was observed with 4–I .…”