Hydrozirconation of an η2-ligated phosphaalkyne. A new synthetic route to η2-ligated phosphaalkenes

Article abstract of DOI:10.1039/a703201c

The phosphaalkyne complex [Pt(dppe)(η²-Bu^tC≡P)] undergoes ready hydrozirconation with [ZrHCl(η⁵-C₅H₅)₂] to give the metallaphosphaalkene complex [Pt(dppe){η²-Bu^tCH=PZrCl(η⁵-C ₅H₅)₂}] which is a useful precursor for the synthesis of η²-phosphaalkene complexes.

Full text of DOI:10.1039/a703201c

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2
Hydrozirconation of an h -ligated phosphaalkyne. A new synthetic route to
2
h -ligated phosphaalkenes
Maria Helena A. Benvenutti, Nathalie Cenac and John F. Nixon*
School of Chemistry, Physics and Environmental Science, University of Sussex, Brighton, Sussex, UK, BN1 9QJ
2
The phosphaalkyne complex [Pt(dppe)(h -ButC·P)] under-
new approach; furthermore as discussed elsewhere,5 the
reactivity of 2 towards halogeno-compounds offers con-
siderable synthetic potential to generate other metallaphos-
phaalkene complexes by treatment with appropriate metal
halides.
We thank both the EPSRC and the EEC/CNPq for their
financial support of other aspects of phosphaalkyne chemistry
research at Sussex.
5
goes ready hydrozirconation with [ZrHCl(h -C5H5)2] to give
2
the
metallaphosphaalkene
complex
[Pt(dppe){h -
ButCHNPZrCl(h -C5H5)2}] which is a useful precursor for
5
2
the synthesis of h -phosphaalkene complexes.
The recent report of the formation of a phosphaalkenyl
ruthenium(ii) complex by hydroruthenation of the phos-
phaalkyne ButC·P1,2 prompts us to describe the first examples
of the facile conversion of the h -ligated ButC·P by a synthetic
2
route which offers considerable potential for the synthesis of a
2
range of h -ligated ButCHNPX derivatives.
Footnotes
Thus treatment of [Pt(dppe)(h -ButC·P)] 13 with the
2
* E-mail: j.nixon@sussex.ac.uk
5
Schwartz reagent, [ZrHCl(h -C5H5)2], quantitatively affords
† NMR data for 2: 31P {1H} (121.4 MHz, C6D6); d 47.7 (dd, CH2PPh2, 2JPP
53.9, 2JPP 35.5, 1JPPt 3233.6 Hz), 52.7 (dd, PCBut, 2JPP 35.5, 2JPP 15.3, 1JPPt
282.2 Hz). 13C{1H} (75.4 MHz, C6D6); d 30.5 (dd, CH2, JCP 33.0, JCP 15.9,
2JCPt 16.0 Hz), 33.2 (dd, CH2, JCP 32.4, JCP 14.7, 2JCPt 19.0 Hz), 33.8 (dd,
CH3, JCP 6.1, JCP 5.7, 3JCPt 32.9 Hz), 74.1 (ddd, CH, JCP 83.6, JCP 50.0, 2JCP
3.7, JCPt 341.3 Hz), 109.6–109.7 (m, C5H5), 126.5 (s, Ph), 126.9 (dd, Ph, JCP
8.4, JCP 0.8 Hz), 127.3 (d, Ph, JCP 6.0 Hz), 127.6 (d, Ph, JCP 9.9 Hz), 128.1
(dd, Ph, JCP 42.5, JCP 1.1, JCPt 54.7 Hz), 129.3 (dd, Ph, JCP 38.8, JCP 10.0
Hz), 130.9 (d, Ph, JCP 11.0, JCPt 11.2 Hz), 131.4 (d, Ph, JCP 12.6, JCPt 19.0
Hz), 133.1 (d, Ph, JCP 12.6, JCPt 21.8 Hz), 134.4 (dd, Ph, JCP 13.7, JCP 2.4,
2
2
the h -ligated metallaphosphaalkene complex [Pt(dppe){h -
ButCHNPZrCl(h -C5H5)2}] 2 which occurs as a single iso-
5
mer.†
PZrCl(η5-C5H5)2
(dppe)Pt
CHBut
2
J
CPt 24.2 Hz); quaternary carbons unidentified. 1H (300 MHz, C6D6); d 1.28
5
(s, 9 H, CH3), 2.00 (m, 4 H, CH2), 4.19 (ddd, 1 H, CH, JHP 7.5, JHP 7.5, JHP
3.8, 2JHPt 55.6 Hz), 5.80–6.01 (m, 10 H, C5H5), 6.80–8.21 (m, 20 H, Ph).
‡ NMR data for 3a and 3b: 3a 31P{1H} (C6D6); d 154.7 (dd, PH, JPP 52.1,
It is interesting to note that the [ZrCl(h -C5H5)2] fragment
adds solely to the phosphorus atom which is at the positive end
of the dipole in uncoordinated ButC·P. Hydrozirconation of
phosphaalkenes R2CNPRA has been the subject of a very recent
review,3 where it was pointed out that the course of these
reactions depends strongly on the nature of the substituents
attached to phosphorus or carbon.
J
PP 11.0, JPPt 286.7, JPH 138.5 Hz), 51.8 (dd, PPh2, JPP 52.1, JPP 45.8, JPPt
3226.1 Hz), 56.9 (dd, PPh2, JPP 45.8, JPP 11.0, JPPt 2929.7 Hz). 13C{1H}
(thf); d 27.5 (dd, CH2, JCP 32.6, JCP 14.1, 2JCPt 13.9 Hz), 31.5 (dd, CH2, JCP
2
3
33.6, JCP 18.1, JCPt 20.5 Hz), 33.8 (dd, CH3, JCP 8.5, JCP 5.8, JCPt 30.7
Hz), 69.6 (ddd, CH, JCP 65.9, JCP 52.0, JCP 4.2 Hz), 126.5–134.3 (m, Ph);
quaternary carbons unidentified. 1H (C6D6); d 1.41 (s, 9 H, CH3), 2.00 (m,
4 H, CH2), 2.70 (ddd, PH, 1JHP 150, 3JHP 12.5, 3JHH 9.6, 2JHPt 51.8 Hz), 4.38
Treatment of 2 with H2O at 260 °C in thf for 1 h readily
2
2
affords the yellow h -phosphaalkene complex [Pt(dppe)(h -
ButCHNPH)] as a 3:1 mixture of cis- and trans-isomers 3a and
3b.‡ The uncoordinated phosphaalkene is unknown.
2
3
3
3
2
(dddd, 1 H, CH, JHP 18.8, JHH 9.6, JHP 3.0, JHP 3.1, JHPt 58.0 Hz),
6.99–8.15 (m, 2 Ph). 3b 31P{1H} for the minor product: d 2167.0 (dd, PH,
3JPP 49.9, JPP 6.2, JPPt 325.6, JPH 145.8 Hz), 50.3 (dd, PPh2, JPP 49.9, JPP
48.0, JPPt 3237.7 Hz), 56.9 (dd, PPh2, JPP 48.0, JPP 6.2, JPPt 2929.7 Hz).
§ NMR data for 4: 31P{1H} (CD2Cl2) d 280.0 (ddd, PCH, 1JPP 213.2, 2JPP
54.0, 2JPP 9.6, 1JPPt 297.9 Hz), 212.7 (ddd, PPh2, 1JPP 213.2, 3JPP 9.4, 3JPP
5.8, 2JPPt 38.0 Hz), 51.5 (ddd, CH2PPh2, 2JPP 54.0, 2JPP 39.8, 3JPP 5.8, 1JPPt
3198.0 Hz), 53.9 (ddd, CH2PPh2, 2JPP 39.8, 2JPP 9.6, 3JPP 5.4, 1JPPt 2951.5
Hz).
PH
(dppe)Pt
CHBut
3
The synthetic potential of the intermediate 2 in the generation
of other phosphaalkene complexes is illustrated by its reaction
5
with Ph2PCl leading to ready elimination of [ZrCl2(h -C5H5)2]
References
and formation of the diphenylphosphino-phosphaalkene com-
2
plex [Pt(dppe)(h -ButCHNPPPh2)] 4 as a mixture of cis- and
1 R. B. Bedford, A. F. Hill and C. Jones, Angew. Chem., Int. Ed. Engl.,
1996, 35, 547.
trans-isomers.§
2 R. B. Bedford, A. F. Hill, C. Jones, A. J. P. White, D. J. Williams and
J. D. E. T. Wilton-Ely, Chem. Commun., 1997, 179.
3 J.-P. Majoral, M. Zablocka, A. Igau and N. Cenac, Chem. Ber., 1996, 129,
879.
4 L. Weber, Angew. Chem., Int. Ed. Engl., 1996, 35, 271.
5 M. H. A. Benvenutti, N. Cenac, S. D’Arbeloff and J. F. Nixon, paper in
preparation.
PPPh2
(dppe)Pt
CHBut
4
The field of metallaphosphaalkene complexes has recently
been reviewed by Weber4 but the synthesis of 2 represents a
Received in Cambridge, UK, 9th May 1997; Com. 7/03201C
Chem. Commun., 1997
1327