Synthesis and characterization of the neutral dinuclear hydrido complexes of platinum with bridging phosphides c/s-Pt2(H)2(PHBut2)2(-4-H)(n-PBut2) (Pt-Pt) and fraAW-[Pt(H)(PHBu'2)(u-PBu'2)]2 (Pt-Pt)

Article abstract of DOI:10.1039/b006341j

/raHs-PtCl₂(PHBu'2)₂ 1 reacts with NaBH4 in THF affording the dinuclear platinum(n) complexes cw-Pt2(H)₂(PHBu'2)₂(n-H)(u-PBu'2) (Pt-Pt) 2 and ?ra/is-[Pt(H)(PHBu'2)(u-PBu'2)]₂ (Pt-Pt) 3 along with the

Full text of DOI:10.1039/b006341j

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Synthesis and characterization of the neutral dinuclear hydrido
complexes of platinum with bridging phosphides cis-Pt (H) -
2
2
t
t
2
t
(
(
PHBu ) (ꢀ-H)(ꢀ-PBu ) (Pt–Pt) and trans-[Pt(H)(PHBu )-
2
2
2
t
ꢀ-PBu )] (Pt–Pt)
2
2
a
a
b
Piero Mastrorilli,* Mariangela Palma, Francesco Paolo Fanizzi and
a
Cosimo Francesco Nobile
a
Centro C.N.R. M.I.S.O. and Istituto di Chimica del Politecnico di Bari, via Orabona 4,
0125 Bari, Italy
Dipartimento di Biologia, Università di Lecce, via Monteroni, I-73100, Lecce, Italy and
Consortium C.A.R.S.O., Cancer Research Center, I-70010, Valenzano - Bari, Italy
7
b
Received 3rd August 2000, Accepted 11th October 2000
First published as an Advance Article on the web 16th November 2000
t
trans-PtCl (PHBu ) 1 reacts with NaBH in THF affording the dinuclear platinum() complexes cis-Pt (H) -
(
2
2
2
4
2
2
t
t
t
t
PHBu ) (µ-H)(µ-PBu ) (Pt–Pt) 2 and trans-[Pt(H)(PHBu )(µ-PBu )] (Pt–Pt) 3 along with the boron adduct
2 2 2 2 2 2
t
BH ؒPHBu 4. Pure 2 can be obtained in 85% yield in the reaction carried out in the presence of two equivalents
3
2
of di-tert-butylphosphine.
3
1
1
Introduction
during the reaction, the P{ H} NMR spectrum of the solution
showed three sets of signals which could be assigned to
three different species. A quartet (four 1:1:1:1 lines) without
We have recently described the spectroscopic and XRD charac-
terization of trans-PtCl (PHBu ) 1 that exists as a mixture of
t
2
2 2
195
Pt satellites centered at δ 48.84 with a coupling constant of
6.5 Hz, which split into a doublet of quartets [J(PH) 349 Hz]
in the proton coupled spectrum, could be easily assigned to the
BH –PHBu Lewis adduct 4. Such a species is characterised
by the observed B P 46.5 Hz coupling constant. Moreover
H, P, C and B NMR data of compound 4 are identical
with those of a pure sample of the adduct synthesised by con-
densation of PHBu with BH ؒMe S (at Ϫ20 ЊC) or BH ؒEt O
1
,2
rotational conformers. Aiming at preparing new, low-valent
platinum complexes a sodium reduction of 1 was carried out,
leading to a mixture of compounds among which the presence
4
t
2
t
2
t
1
3
of [Pt(µ-PBu )(PHBu )] could be detected.
11 31
2
2
Reductants commonly employed to access low-valent transi-
1
31
13
11
3
tion metal complexes such as sodium naphthalenide, zinc
4
5
dust and sodium methoxide were used unsuccessfully since
no reaction with 1 took place.
t
2
9
3
2
3
2
(
at room temperature).
The reactivity of sodium borohydride towards transition
metal complexes has been long studied, both for the prepar-
ation of zero-valent phosphino- and arsino- complexes, and
for the synthesis of hydrido species. In particular, NaBH4
reaction with Pt() dichloride diphosphine complexes, either
in the presence or absence of molecular hydrogen, resulted
nearly always in the substitution of one or both the chlorine
31
1
The other two sets of signals observed in the P{ H} NMR
spectrum of the filtrate reaction solution are both Pt coupled
and can be assigned to a mixture (ca. 1:1) of cis-Pt (H) -
195
6
2
2
t
t
t
(
(
PHBu ) (µ-H)(µ-PBu ) (Pt–Pt) 2 and trans-[Pt(H)(PHBu )-
2 2 2 2
t
µ-PBu )] (Pt–Pt) 3 on the basis of their multinuclear NMR
2
2
features. Ethanol extraction of the crude product obtained after
solvent evaporation from the filtrate allowed the removal of
adduct 4 from the mixture of the two Pt complexes. The lower
solubility of 2 with respect to 3 in a 1:1 C H –MeCN solution
allowed selective enrichment of 3 in the mixture, whereas pure
complex 2 could be synthesised by an alternative route as
described below.
The P{ H} NMR spectrum of complex 2 consists of two
signals coupled with each other [J(PP) 271 Hz], both flanked by
Pt satellites and centred at δ 188.0 (triplet) and 53.3 (doublet),
7
atoms with co-ordinated hydrides. Such hydrides, depending
on the bulkiness of the phosphorus ligands, can vary from
being very unstable (unhindered phosphines) in air to thermally
very stable (bulky phosphines). The only case of a PtCl P –
6
6
2
2
NaBH reaction that does not give rise to chloro/hydrogen
4
8
exchange is that reported by Brown and co-workers on PtCl -
31
1
2
(
dppm) [dppm = bis(diphenylphosphino)methane]. Such a
ϩ
reaction led to the binuclear cation [Pt H (µ-H)(µ-dppm) ] .
The reaction of NaBH4 with 1 carried out in refluxing
THF resulted in the synthesis of two neutral dimeric hydrido
complexes: cis-Pt (H) (PHBu ) (µ-H)(µ-PBu ) (Pt–Pt) 2 and
trans-[Pt(H)(PHBu )(µ-PBu )] (Pt–Pt) 3. The concomitant
formation of 3 was prevented by carrying out the reaction in
the presence of free di-tert-butylphosphine (PHBu ).
195
2
2
2
respectively (Fig. 1).
In the proton coupled spectrum the doublet split into a
doublet of doublets [J(PH) 323 Hz], and the triplet gave rise
only to negligible splitting. These findings, along with the
observation that low field P NMR resonances are charac-
teristic for bridging phosphides involved in three-membered
rings, support a dimeric structure in which two platinum
atoms, each carrying one terminal PHBu , are bridged by a
PBu 2 group. The large value of the phosphorus–phosphorus
coupling constant suggests that both of the terminally co-
t
t
2
2
2
2
2
t
t
2
2
2
31
t
2
10
t
2
Results and discussion
When a suspension of trans-PtCl (PHBu ) 1 was reacted for
t
t
2
2 2
1
2 h with NaBH in THF at reflux, hydrogen evolution was
ordinated phosphines are trans to the bridging phosphide.
The H NMR spectrum of 2 shows (i) a broad doublet
4
1
detected and a black suspension was obtained. After filtering
off the excess NaBH and the NaCl and platinum metal formed
centered at δ 5.02, (ii) two doublets in a 1:2 ratio at δ 1.55 and
4
4
272
J. Chem. Soc., Dalton Trans., 2000, 4272–4276
This journal is © The Royal Society of Chemistry 2000
DOI: 10.1039/b006341j

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1
Fig. 4 F2 projection of the 2D H J-resolved NMR spectrum of 2 in
the hydride region.
31
1
Fig. 1
P{ H} NMR spectrum of 2 (C D ).
6 6
1
Fig. 2 Hydride region in the H NMR spectrum of 2 (C D ).
6
6
Fig. 5 F1 slices of the δ Ϫ5.39 and Ϫ6.22 proton signals from the 2D
1
H J-resolved spectrum of 2: (a) terminal hydrides; (b) bridging hydride.
coupling in molecules containing one or two NMR active Pt
atoms, is also in accord with the presence of one bridging
hydride.
In order to extract the values for the coupling constants
between the terminal and bridging hydrides as well as between
the hydrides and the phosphorus atoms, a J-resolved 2D-NMR
experiment on a benzene-d6 solution of 2 was carried out
(
Fig. 3). In such an experiment the multiplets due to H–H
coupling are tilted in the second dimension (F1) and the
residual pattern, easily detected as the projection in the first
dimension (F2 projection), only contains the couplings between
hydrogens and heteroatoms.
The F2 projection of the terminal hydride signals consists of
a sharp doublet of doublets due to the isotopomer containing
no NMR active Pt atoms, in addition to lower signals due to the
H–Pt couplings in the isotopomers containing one or two NMR
active Pt atoms. In F2, the bridging hydride gives a doublet of
1
Fig. 3 Contour plot of the 2D H J-resolved NMR spectrum of 2
2
1
triplets due to couplings with the bridging phosphide [ J(HP)
(
hydride region). The top trace refers to the projection on the
H
2
chemical shift axis.
14 Hz] and terminal phosphines [ J(HP) 11 Hz], respectively
(
Fig. 4).
1
.32, and (iii) two further multiplets in a 2:1 ratio, both
Pt coupled, and centered at δ Ϫ5.39 and Ϫ6.22 (Fig. 2).
In the F1 dimension the signal of the terminal hydrides
195
results in a doublet of multiplets deriving from the overlapping
of two spin systems: an AAЈMXXЈ, due to the isotopomer
containing no or both NMR active Pt atoms, and an ABMXY,
due to the isotopomer containing only one NMR active
Pt atom. From this pattern it was possible to extract only the
These signals can be ascribed to: (i) the hydrogen directly bound
t
2
to the phosphorus atom for the co-ordinated PBu H
1
[
J(PH) 323 Hz], (ii) the tert-butyl groups of the phosphines
3
and of the phosphide [ J(PH) 14.2 and 13.8 Hz, respectively],
and (iii) two different kinds of co-ordinated hydrides.
Pt coupling of the upfield signals at δ Ϫ5.39 [ J(PtH) 1378
Hz] and Ϫ6.22 [J(PtH) 411 Hz] are typical for terminal and
2
J(HH) 12 Hz with the bridging hydride (Fig. 5).
195
1
The signal of the bridging hydride in the F1 dimension
consists of a sharp triplet of triplets due to the couplings with
8b,11
2
bridging hydrides respectively.
These experimental data
the terminal hydrides [ J(HH) 12 Hz] and with the hydrogens
suggest the dimeric structure proposed for 2 characterised by
directly bound to the phosphorus atoms in the terminal
3
two terminal hydrides cis to the bridging phosphide and one
phosphines [ J(HH) 5.5 Hz].
195
195
1
bridging hydride. The Pt satellite pattern of the δ Ϫ6.22
signal, which consists of two sets of resonances due to H–Pt
The Pt{ H} NMR spectrum (Fig. 6) consists of a doublet
of doublets of doublets centered at δ Ϫ5995 due to the
J. Chem. Soc., Dalton Trans., 2000, 4272–4276
4273

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12
a
in which J(XXЈ) = 0. Computer simulation of the spectrum,
Table 1 NMR parameters for 2
using as starting chemical shifts and coupling constants those
extractable directly from the experimental spectrum, gave
13
1
2
1
2
3
P
P
H
H
H
Pt
the following parameters: δ(P ) = 191.8, δ(P ) = 55.5 ppm,
b
t
2
2
2
2
2
1
2
J(AX) = J(AЈXЈ) = 264 Hz, J(AXЈ) = J(AЈX) = –1.5 Hz,
J(AAЈ) = 210 Hz.
Minor signals due to Pt satellites for the isotopomers con-
P
P
188.0
271
5.5
271
53.3
23.4
323
11
5.5
14
11
12
5.5
؊6.22
411
2105
2643
1378
23.4
؊5.39
1.5
323
1.5
5.02
5.5
1
2
3
195
H
H
H
taining one or two magnetically active platinum atoms allowed
14
12
411
؊5995
1
the calculation of J(PtP ) 2643 Hz (separation of the terminal
t
Pt
2105
2643
1378
1
phosphine satellites) and of the mean of the two J(PtPµ)
a
Solvent C D ; chemical shifts (bold typeface) are in ppm; coupling
6
6
coupling constants (1963 Hz, separation of the bridging
constants (normal type) are in Hz.
13
phosphide satellites).
1
The H spectrum shows, besides the resonances ascribed to
tert-butyl methyls and the PH signals [δ 5.25, J(PH) 318 Hz] a
multiplet centred at δ Ϫ5.40 flanked by two satellites [ J(HPt)
505 Hz] in the hydride region. The value of J(HPt) is again
1
H
1
1
1
in agreement with the proposed terminal co-ordination of the
hydrides. The satellites are doublets of pseudotriplets, owing to
the coupling with the phosphorus atoms.
195
1
The Pt{ H} NMR spectrum of 3 allowed assignment of
the chemical shift of the platinum atoms (δ Ϫ5914), to con-
Pt
1
2
firm the J(PtP ) (2643 Hz) and to extract the J(PPt) (64 Hz)
t
between the magnetically active platinum and the terminal
phosphine co-ordinated to the other platinum atom.
The main IR features of 3 could be obtained recording the
spectrum of the solid enriched in 3 (3:2 = 3.7:1). P–H and
Ϫ1
Pt–H stretching were found respectively at 2294 and 2085 cm .
Complex 3 has been proposed by Leoni et al. as the result
3
t
2
of the reaction of CpPt(η -C H ) with PHBu on the basis of
3
5
14
its reactivity. However, the authors describe the complex as
sparingly soluble in all common organic solvents. The dis-
crepancy between these results and ours can be explained by
admitting that the complex prepared by Leoni’s group is an
oligomer of 3. This could account for both its reactivity and its
lack of solubility.
195
1
Fig. 6
Pt{ H} NMR spectrum of 2 (C D ).
6 6
When NaBH reduction of 1 was carried out in the presence
4
t
of free PHBu 2 (2:1 P:Pt ratio) the reaction resulted in the
selective synthesis in high yield (85%) of complex 2. Pure 2 is
a white microcrystalline powder soluble in aromatic solvents
and THF, scarcely soluble in ethanol, methanol and diethyl
ether and insoluble in acetone and acetonitrile. Its IR spectrum
recorded in Nujol mull shows two strong sharp bands at 2067
Ϫ1
Ϫ1
and 2293 cm . The 2293 cm band is ascribable to the P–H
stretching of the co-ordinated di-tert-butylphosphines, whereas
Ϫ1
the 2067 cm band is ascribable to the Pt–H stretching of
the terminal hydrides. Similar resonances have been found
t
for the hydrido binuclear complexes [Pt (µ-PBu ) (H)-
2
Ϫ1
2
2
t
Ϫ1
15
(
PHBu ) ]C (CN) [2289 cm (νPH), 2031 cm (νPtH)], [Pt -
2
2
3
5
2
16
3
1
1
Ϫ1
Ϫ1
Fig. 7
P{ H} NMR spectrum of 3 (C D ). Asterisked peaks refer to
(µ-H)(H)(PCy )]2 [2090 cm (νPtH-t), 1550 cm (νPtH-b)],
3
Ϫ1
6
6
residual 2.
[Pt [P–P*] (H) ][BF ] [P–P* = (S)-prolophos: 2015 cm (νPtH);
2
2
3
4
Ϫ1
17
P–P* = (S)-butaphos: 2000 cm (νPtH)], [Pt [P–P] (H) ][BF ]
2
2
3
18
4
Ϫ1
isotopomer containing only one NMR active platinum atom
[
P–P = chelating diphosphine; 1975–2060 cm (νPtH)] and
1
1
2
t
t
t
[
J(PtP ) 2643 Hz, J(PtP ) 2105 Hz and J(PtP ) 43 Hz],
H {R(Bu )P(CH ) PR(Bu )} ]X [R = Bu , Ph; n = 2, 3;
t
µ
t
[Pt
2
3
2
n
2
Ϫ1
Ϫ1
19
together with minor signals originated by the X part of an
AAЈMXXЈ spin system (A and M are phosphorus atoms) due
to the isotopomer containing both NMR active platinum
atoms. The main multinuclear NMR features for 2 are collected
in Table 1.
X = BPh , OMe; 2000–2045 cm (νPtH-t), 1650 cm (νPtH-b)].
4
Ϫ1
A band centred at 1630 cm was also present in the IR
20
spectrum of 2 ascribable to Pt–H–Pt stretching.
The suggested mechanism for the formation of 2 is depicted
in Chart 1. The first step is the expected substitution of one
chloro ligand with a hydride leading to species A (all species
labeled with capital letters are supposed to be transient in solu-
tion). Such a species could in turn undergo HCl elimination
The other platinum complex present in the reaction mixture
31
1
showed the P{ H} NMR spectrum reported in Fig. 7. The
spectrum mainly consists of two sextets centered at δ 191.8 and
5
5.5, typical for two chemically equivalent bridging phosphides
responsible for the observed H2 evolution in the presence of
(
and two chemically equivalent terminal phosphines {further
splitting [J(PH) 318 Hz] is observed in the proton coupled
spectrum}, respectively, of a AAЈXXЈ spin system of the type
NaBH ) with formation of the terminal phosphido–hydrido co-
ordinatively unsaturated Pt() intermediate B. This intermedi-
ate could either give dimerisation with formation of 3 or react
4
4
274
J. Chem. Soc., Dalton Trans., 2000, 4272–4276

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Chart 1
with A to give the dimeric species C via nucleophilic attack of
2, 3 and 4, a weak doublet of doublets centered at δ 186 with
the electron-rich terminal phosphido ligand on the electrophilic
Pt centre of A which, in turn, undergoes displacement of one
phosphine and transformation of the terminal into bridging
hydride. Species C could generate 2 by further substitution of
the chloride with a hydride owing to the presence of excess
NaBH4.
trans J(PP) 263 and 228 Hz ascribable to the bridging
phosphide of C. Unfortunately, the crowding of peaks due to
the presence of 2, 3 and 4 did not allow the corresponding
signals in the PH region to be exactly located.
Experimental
It cannot be excluded that substitution of both chlorides with
Ϫ
hydrides could also take place by reaction of BH4 with 1 with
All manipulations were carried out under a pure dinitrogen
atmosphere, using freshly distilled and oxygen-free solvents.
Di-tert-butylphosphine was purchased from Aldrich and used
formation of the trans-dihydride D. In this case the formation
of 2 could be derived by nucleophilic attack of the phosphido
species B on D.
t
as received. trans-PtCl (PHBu ) was prepared as previously
described.
2
2 2
1
The key step of the proposed mechanism, e.g. the formation
of HCl from the moiety cis-M(Cl)(PR H) (M = metal) has
2
Infrared spectra were recorded on a Perkin-Elmer Spectrum
One spectrometer. Elemental analyses were carried out by using
a Carlo Erba model EA 1108 elemental analyser. NMR spectra
were recorded on a Bruker Avance DRX500 spectrometer
been already observed for the synthesis of complexes of type
21
13
[
M X (µ-PRЈ ) (PR ) ] (M = Pd, Pt ).
2 2 2 2 3 2
The observation that, in the presence of excess phosphine,
only 2 is formed in high yield and no platinum metal forms
could be explained invoking two main effects. The free phos-
1
13
(
CARSO); frequencies are referenced to Me Si ( H, C), 85%
4
31 11 195
H PO ( P), BF ؒEt O ( B) and H PtCl ( Pt). Simulated
3
4
3
2
2
6
phine could sequestrate the BH as it forms, giving the adduct
3
spectra were calculated with the program MestRe-C 2.0
t
2
3
PHBu ؒBH 4, and stabilise the intermediate B by occupying the
3
assuming the J(PP) between the two terminal phosphorus
free co-ordination site according to the following equilibrium.
atoms to be equal to zero.
Reaction of 1 with sodium borohydride
NaBH (0.200 g, 5.3 mmol) was added to a THF solution
4
t
3
of trans-PtCl (PHBu ) (0.651 g, 1.17 mmol in 20 cm ). The
2
2 2
resulting suspension was stirred at reflux for 12 h. Filtration
of the suspension and evaporation of the solvent from the
filtrate afforded a dark residue that was washed three times
The presence of such an equilibrium lowers the concen-
tration of B in solution and renders its dimerisation to 3
unlikely. As to the formation of platinum metal it may be due
to decomposition of species E formed by reaction between
3
with ethanol (3 × 7 cm ). A pale yellow solid (0.155 g) was
so obtained, the spectroscopic features of which indicate as a
mixture of 2 and 3 in a 1:1 ratio. Treating this mixture with
C H –MeCN 1:1 followed by filtration afforded a solution that
BH and B.
3
In order to verify this hypothesis we carried out an experi-
6
6
ment reacting 1 with excess NaBH in the presence of one
4
1
31
contained 2 and 3 in a 1:3.7 ratio as revealed by H and
P
equivalent of BH ؒEt O. This reaction led to the formation
3
2
NMR. Main NMR features of 3 are collected in Table 2. NMR
of only platinum metal, hydrogen, the adduct 4 and NaCl
according to the stoichiometry:
data other than those collected in Table 2 are, δ (C D ): 1.55
H
6
6
3
t
t
3
t
[
36H, d, J(Bu P ) 13.9 Hz, 4 Bu P ], 1.35 [36H, d, J(Bu P ) 13.9
t
t Ϫ1
µ
µ
t
2
Hz, 4 Bu P
]. IR (Nujol, νmax/cm ): (PH) 2294s, (PtH) 2085vs.
t
PtCl (PHBu ) ϩ 2 NaBH →
2
2
4
t
2
NaCl ϩ Pt ϩ H ϩ 2 BH ؒPHBu
2
2
3
Synthesis of [cis-dihydride-bis(di-tert-butylphosphine)-
(
ꢀ-hydride)(ꢀ-di-tert-butylphosphide)diplatinum(II)] 2
Although the attempts to isolate C were unsuccessful, the
31
1
t
P{ H} NMR spectrum of the crude product obtained after
filtration of excess NaBH showed, apart from the signals of
PHBu 2 (0.297 g, 2.03 mmol) was added to a solution of 1
in THF (0.567 g, 1.015 mmol in 20 cm ). NaBH (0.179 g,
3
4
4
J. Chem. Soc., Dalton Trans., 2000, 4272–4276
4275

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3
4
J. Chatt and G. A. Rowe, Nature, 1961, 191, 1191; J. Chatt, F. A.
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a
Table 2 NMR parameters for 3
2
1
2
3
1
2
6 L. Malatesta and S. Cenini, in Zerovalent Compounds of Metals,
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P
P
P
H
H
Pt
1
2
3
b
P
P
P
191.8
264
210
7
264
55.5
Ϫ1.5
7
318
2643
210
7
7
Ϫ1.5
191.8
23
318
b2643
7
B. L. Shaw and M. F. Uttley, J. Chem. Soc., Chem. Commun., 1974,
23
؊5.40
1.5
918; C. J. Moulton and B. L. Shaw, J. Chem. Soc., Chem. Commun.,
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2
H
H
1.5
5.25
1505
1
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b
b
Pt
1505
؊5914
a
Solvent C D ; chemical shifts (bold typeface) are in ppm; coupling
constants (normal type) are in Hz. [ J(PtP ) ϩ J(PtP )]/2 = 1963 Hz.
6
6
b
1
1
1
3
2
70, 363.
8
(a) M. P. Brown, R. J. Puddephatt, M. Rashidi and K. R. Seddon,
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5
.1 mmol) was then added to the yellow solution and stirred
at reflux for 20 h. The resulting white suspension was filtered
off and a colourless solution of cis-Pt (H) (PHBu ) (µ-H)-
5
16.
t
9 A. C. Gaumont, K. Bourumeau, J. M. Denis and P. Guenot,
J. Organomet. Chem., 1994, 484, 9.
10 P. E. Garrou, Chem. Rev., 1981, 81, 229; A. J. Carty, S. A.
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Bachechi, G. Bracher, D. M. Grove, B. Kellenberger, P. S. Pregosin,
L. M. Venanzi and L. Zambonelli, Inorg. Chem., 1983, 22, 1031;
R. S. Paonessa and W. C. Trogler, J. Am. Chem. Soc., 1982, 104,
2
2
2 2
t
t
(
µ-PBu ) 2 and BH ؒPHBu 4 was obtained. Evaporation of
2 3 2
3
the solvent followed by extraction of 4 with ethanol (3 × 7 cm )
yielded pure 2 as a white microcrystalline powder (0.361 g,
5%). mp (C H –MeCN) 200 ЊC decomp. (Found: C, 34.41; H,
6 6
.12; P, 11.08. C H P Pt requires C, 34.70; H, 7.16; P,
1.18%). IR (Nujol, νmax/cm ): (PH) 2293s, (PtH ) 2067vs,
PtH ) 1630m, 1261m, 1180m, 941w, 905m, 853s, 814vs, 682s,
20w, 588m, 468s, 390w. NMR data other than those collected
in Table 1 are, δ (C D ) 1.55 [18H, d, J(Bu P) 14.2 Hz, 2
Bu P ], 1.32 [36H, d, J(Bu P) 13.8 Hz, 4 Bu P ]; J(PtH ) 38
8
7
1
(
6
1
24
59
3
2
Ϫ1
t
b
3
t
H
6
3
6
t
1
t
t
2
2
3
529; M. P. Brown, S. J. Cooper, A. A. Frew, L. Manoijlovic-Muir,
t
Ϫ1
2
3
Ϫ1
K. W. Muir, R. J. Puddephatt and M. A. Thomson, J. Chem.
Soc., Dalton Trans., 1982, 299; A. R. Siedle, R. A. Newmark and
W. B . Gleason, J. Am. Chem. Soc., 1986, 108, 767; J. Jans, R. Naegeli,
L. M. Venanzi and A. Albinati, J. Organomet. Chem., 1983, 247,
C37; P. W. N. M. van Leeuwen, C. F. Roobeek, J. H. G. Frijns and
A. G. Orpen, Organometallics, 1990, 9, 1211; A. L. Bandini,
G. Banditelli and G. Minghetti, J. Organomet. Chem., 2000,
595, 224.
Hz; J(PtP ) 43 Hz. UV/VIS [λ /nm (ε/dm mol cm )] in
toluene (5.8 × 10 mol dm ): 287 (5280), 280 (2000).
t
max
Ϫ4
Ϫ3
Synthesis of di-tert-butylphosphineborane 4
t
3
PBu H (0.386 g, 2.65 mmol) was dissolved in 1.5 cm of THF
and 2.8 ml of a 1.0 mol dm BH solution in THF was added,
dropwise, and the system stirred for 45 min. The solution was
evaporated in vacuo obtaining pure 4 as a white solid (416 mg,
8%). Mp 64.8 ЊC (Found: C, 60.11; H, 13.79; P, 19.22. Calc. for
C H BP: C, 60.04; H, 13.86; P, 19.35%). IR (Nujol, ν /cm ):
2
Ϫ3
3
1
2 F. A. Bovey, Nuclear Magnetic Resonance Spectroscopy, Academic
Press, New York and London, 1969, p. 117.
3 J. B. Brandon and K. R. Dixon, Can. J. Chem., 1981, 59, 1188.
4 P. Leoni, S. Manetti and M. Pasquali, Inorg. Chem., 1995, 34,
749.
1
1
9
Ϫ1
8
22
max
2
1
8
3
384vs, (B–H) 2351vs, 2276m, (P–H) 2258m, 2125w, 1467vs,
15 P. Leoni, M. Pasquali, A. Fortunelli, G. Germano and A. Albinati,
J. Am. Chem. Soc., 1998, 120, 9564.
16 M. Green, J. A. K. Howard, J. Proud, J. L. Spencer, F. G. A. Stone
and C. A. Tsipis, J. Chem. Soc., Chem. Commun., 1976, 671.
393m, (B–P) 1369vs, 1196s, 1137s, 1066vs, 1025vs, 906vs,
1
19vs, 692s, 625s, 543m. NMR, δ (CDCl ): 3.74 [dq, J(PH)
H
3
3
1
3
49, J(HH) 6.8], 1.25 [qm, J(HB) 100], 1.033 [d, J(HP) 13.2];
1
7 A. L. Bandini, G. Banditelli, E. Cesarotti, F. Demartin,
M. Manassero and G. Minghetti, Gazz. Chim. Ital., 1994, 124,
43.
2
1
31
1
δ (CDCl ): 28.92 [d, J(CP) 1.7], 30.35 [d, J(CP) 27.0]; P{ H}
C
3
1
1
(
CDCl ): 48.84 [q, J(PB) 46.5]; δ (CDCl ): Ϫ42.69 [dq, J(BP)
3
B
3
1
4
6.8, J(BH) 98.5].
18 C. B. Knobler, H. D. Kaesz, G. Minghetti, A. L. Bandini,
G. Banditelli and F. Bonati, Inorg. Chem., 1983, 22, 2324.
1
2
9 T. H. Tulip, T. Yamagata, T. Yoshida, R. D. Wilson, G. A. Ibers and
S. Otsuka, Inorg. Chem, 1979, 8, 2239.
0 L. Mole, J. L. Spencer, S. A. Litster, A. D. Redhouse, N. Carr and
A. G. Orpen, J. Chem. Soc., Dalton Trans., 1996, 2315.
References
1
R. Giannandrea, P. Mastrorilli, C. F. Nobile, M. Palma, F. P. Fanizzi
and U. Englert, Eur. J. Inorg. Chem., in the press.
21 R. G. Hayter, J. Am. Chem. Soc., 1962, 84, 3046; R. Giannandrea,
P. Mastrorilli and C. F. Nobile, Inorg. Chim. Acta, 1999, 284,
116.
2
A. Bright, B. E. Mann, C. Masters, B. L. Shaw, R. M. Slade and
R. E. Steinbank, J. Chem. Soc. A, 1971, 1826.
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276
J. Chem. Soc., Dalton Trans., 2000, 4272–4276