Formation of η1-P-(2-phosphinophenol)Ni(0)(PMe3)3 and oxidation to cis/trans-bis(2-phosphinophenolato)nickel(II) complexes

Article abstract of DOI:10.1515/znb-1999-1004

o-Phosphinophenols 1 (P^∩OH) react with equimolar amounts of Ni(PMe₃)₄ at low temperatures to give yellow Ni(0) complexes such as [(HO～P)Ni(PMe₃)₃] 2a with only P coordination of the P^∩OH ligand. Oxidation of solutions of 1 and Ni(PMe₃)₄ by dioxygen leads to brown bis(o-phosphinophenolato-P^∩O)nickel chelate complexes 3a-d. Structure elucidation by NMR is consistent with a cis-square planar geometry for 3a-c and a trans-square planar solution structure of the tert-butylphenylphosphino derivative 3d. The geometric isomers were distinguished by different ranges of phosphorus coordination shifts and ³¹P-¹³C-2 and ³¹P-¹³C-1 coupling constants. In the solid state, 3d adopts also a cis-square planar geometry. The steric stress of the substituents causes anti-orientation of the tert-butyl groups at phosphorus (R,R and S,S diastereoisomers) and a significant distorsion (22°) of the planes of the two five-membered rings. With less bulky substituents the R,S and S,R diastereoisomers are preferred as in the cis-square planar complex 3c with syn-orientation of the two isopropyl and phenyl groups, respectively.

Full text of DOI:10.1515/znb-1999-1004

Formation of r71-P-(2-Phosphinophenol)Ni(0)(PMe3)3and Oxidation
to cjs/fraws-Bis(2-phosphinophenolato)nickel(II) Complexes
Joachim Heinickea*, Attila Dala,b, Hans-Friedrich Kleinb’*, Olaf Hetcheb,
Ulrich Flörkec, and Hans-Jürgen Hauptc
a Institut für Chemie und Biochemie, Universität Greifswald, Soldmannstr. 16,
D-17487 Greifswald, Fax: (+49) 3834 864319, E-mail: heinicke@mail.uni-greifswald.de
b Institut für Anorganische Chemie, Technische Universität Darmstadt, Petersenstr. 18,
D-64285 Darmstadt, Fax: (+49) 6151 164173, E-mail: hfklein@hrz2.hrz.tu-darmstadt.de
c Fachbereich Anorganische und Analytische Chemie, Universität-GH Paderborn,
Warburger Str. 100, D-33098 Paderborn
* Reprint requests to Prof. Dr. J. Heinicke or Prof. Dr. H.-F. Klein.
Dedicated to Prof. Dr. Dr. h. c. Wilhelm Keim on the occasion ofhis 65th birthday
Z. Naturforsch. 54 b, 1235-1243 (1999); received May 19, 1999
Phosphinophenolate, Nickel, Complexes, Structure Elucidation, Solid State Structures
o-Phosphinophenols 1 (P^OH) react with equimolar amounts of Ni(PMe3)4 at low tempera-
tures to give yellow Ni(0) complexes such as [(HO~P)Ni(PMe3)3]2a with only P coordination
of the P^OH ligand. Oxidation of solutions of 1 and Ni(PMe3)4 by dioxygen leads to brown
bis(o-phosphinophenolato-P^O)nickel chelate complexes 3a-d. Structure elucidation by NMR
is consistent with a m-square planar geometry for3a-c and a rrans-square planar solution struc-
ture of the terr-butylphenylphosphino derivative 3d. The geometric isomers were distinguished
by different ranges of phosphorus coordination shifts and 3lP-l3C-2 and 3IP-13C-1 coupling
constants. In the solid state, 3d adopts also a cis-square planar geometry. The steric stress of
the substituents causes üw/z-orientation of the tert-butyl groups at phosphorus (R,R and S,S dia-
stereoisomers) and a significant distorsion (22°) of the planes of the two five-membered rings.
With less bulky substituents the R,S and S,R diastereoisomers are preferred as in the ds-square
planar complex 3c with sw-orientation of the two isopropyl and phenyl groups, respectively.
Introduction
portant as they form nickel complexes which cat-
alyze the polymerization [3 -7] and oligomeriza-
tion [7, 8] of ethylene and can be tuned by sub-
stituents at phosphorus and at the phenoxy group.
Therefore we investigated reactions of 6-ter/-butyl-
The recently reported reaction of substituted
phenols with Ni(PMe3)4 and molecular oxy-
gen in solution gives access to diphenolato-
bis(trimethylphosphine)nickel complexes, the first
representatives of acyclic molecular diphenola-
todiphosphine nickel complexes with a trans-
square-planar arrangement of soft phosphorus and
hard oxygen donor atoms [1, 2], Steric protection
was found to be essential for the existence of these
compounds as monomers. Effective steric shielding
was achieved by either a tert-butyl group, a chloro
or a bromo substituent in ortho-position. When o-
hydroxyaryl aldehydes were used, additional coor-
dination occurred leading to octahedral bis(0 ^ 0 -
2-phosphinophenols with Ni(PMe3
\in absence and
in presence of dioxygen. In this paper the formation
of a new hydroxyfunctional acyclic nickel(O) and
of cyclic bis(phosphinophenolato)nickel(II) com-
plexes is described.
Results and Discussion
Synthesis
2-Phosphinophenols are available by various
methods, including acid cleavage of 2-phosphino-
chelate) complexes with two PMeß ligands in trans- phenol ethers [9,10], metallation and rearrangement
position [1]. In this context the reactivity of phenols of 2-halogenophenoxyphosphines [1 1 ], substitution
bearing other donor groups in ortho-position was
of interest. o-Phosphinophenols are particularly im-
of C,O-dilithium reagents with chlorophosphines
[12], or Pd(0)-catalyzed arylation of PH-functional
0932-0776/99/1(XX)-1235 $ 06.00 (c) 1999 Verlag der Zeitschrift für Naturforschung, Tübingen •www.znaturforsch.com
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J. Heinicke et al. ■Formation of /7 '-P-(2 -Phosphinophenol)Ni(0 )(PMe3)3
1236
qua, 6/ph = 2.4 Hz (PMe3)]. Although the chemical
shift of b = 10.5 shows an increased acidity relative
to free la, a NiHP4+structure (6 = -17) as observed
la
lb
rac-lc rac-Id
for the more acidic phenols [2 ] can be excluded.
R1
R2
Ph
Ph
/Pr
/Bu
/Bu
The PMe integral is in accordance with three PMe3
ligands coordinated tonickel. The l3C data give evi-
dence for /;1-Pcoordination of the P^OH ligand by
doublets with '7 pc-2 = 29 Hz and lJpc-i = 24.4 Hz,
respectively, whereas the chemical shift of C-l is
shifted slightly downfield (zA<5 = 2.3) in contrast
la-d
/Bu
Me
/Bu
phosphines by iodophenol [13]. The representatives
la-d with tert-butyl substituents in o-position to the
hydroxyl group were synthesized by reaction of the
respective chlorophosphines with C,0-lithium/so-
dium reagents and acidic work-up.
to 2-phosphinophenolato Ni(II) complexes
=
Reaction of la with an equimolar amount of
Ni(PMe3)4 dissolved in pentane at low tempera-
ture rapidly led to an intensively yellow solution. In
contrast to the more acidic o-chlorophenol, which
forms with Ni(PMe3)4 a yellow precipitate (op-
timum yield in molar ratio 1:3) of the ion-pair
compound NiH(PMe3)4+H2(2 -C1C6H40 )3” [2], no
crystalline material could be isolated even after pro-
longed reaction periods at 20 °C and storage at
-27 °C. Removal of the solvent and volatile com-
ponents in vacuo furnished a waxy solid which
was identified by IR and multinuclear NMR spec-
troscopy to be the air-sensitive nickel(O) complex
2a (eq. (1)).
16 -19). The l3C resonance (AXYZ2 spin type) of
the trimethylphosphine ligands exhibits a pseudo-
quintet pattern. The 31P coordination shifts [A6 =
42.8 (o-P), 38.6 (PMe3)] are markedly and the 27p p -
coupling constants (33.4 Hz) are strongly reduced
as compared to those of square-planar complexes
of Ni(II) with phosphinophenolato ligands ([6 , 14]
and below).
When the reaction of la-d with Ni(PMe3)4 in
pentane (molar ratio 2 :1) was followed by slow ad-
dition ofdioxygen, 2-phosphinophenolate nickel(II)
complexes were formed. The progress of the con-
version was perceptible by the color change of
the solution to orange-red and later to dark red
or brown. The main part of trimethylphosphine
was oxidized to Me3PO. Work-up afforded 52- 78
P\ /Ph
B u t ^ P ^ f /
PMe3
Ni(PMe3)4
--------►
-78to20 °C
%
of fine red or brown crystals identified as bis-
la
r
y
\PMe3
PMe3
( 1)
(phosphinophenolato-P,0) nickel(II) chelates 3a-d
(eq. (2)). As shown for 3c these complexes were
also formed when the phosphinophenoles were re-
acted with N,N-diallylanilin(trimethylphosphine)-
nickel(O). The structures were elucidated by the
characteristic l3C (AXX' spin type) and proton
(A„XX'A'„ spin type) resonances, partially appear-
ing as triplets or multiplets with “virtual coupling”
(X, X' means 31P). In the cases of 3c and 3d crystal
structure analyses were also performed.
-PMe3
L
2a
The infrared spectrum of 2a shows the bands for
coordinated PMe3 (e.g. pMe at 930 cm "1) in the
range typical for Ni(0) complexes. The z'oh band
is very broad and observed in the range 2500 -
3300 cmr1.The proton NMR reveals a sharp singlet
at 6 = 0.76 for three PMe3 groups and adouble quar-
tet for the hydroxyl proton [d, 47ph = 8 Hz (o-P);
,
W
7
D
U
*
P
h
R
l
R
l
P h
1. Ni(PMe3)4
2. 1-2 O2
r2
la-d
►
or
Ni(PhNAll2)(PMe3)
3a-c
3d (solid)
(2)
3d (solution)
rac-3d
3a
3b
rac-3c
R'
Ph
Ph
/Pr
/Bu
/Bu
R2
/Bu
Me
/Bu
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1237
Table I. Comparison of characteristic NMR data of cis- and frans-bis(2-phosphinophenolato)nickel complexes 3.
J. Heinicke et al. ■Formation of ?7l-P-(2 -Phosphinophenol)Ni(0 )(PMe3)3
Compound
A8m
‘C-l jV(i3C-23
31P2) A6U
C-2 /V(13C-63
P /V(‘3C-1
’P2) 7V(i3C-43IP2)
’P2) A6]2
3a
3b
18.9
17.5
61.2
60
55.8
54
-1.1
« 14
~ 14
12.8
~ 8
« 8
7.2
71.1
70.5
77.5
[6] 74.1
rac-3c
[Ni(2-Ph/PrP-4-MeC6H30)2]
17.7
16.6
19.1
15.5
-5.2
-7.9
6.9
13.8
rac-3d
trans-[Ni(2-/Pr2P-4,6-
rBu2C6H20)2] [14]
28.7
30.5
« 5
6.4
54.0
62.0
15.5
17.1
46.8
42.6
-3.7
-4.7
« 7
7.4
Ph R1
is further supported by the values of N(I3C-131P2)
and /V(l3C-231 P2) (Table I). The former is signifi-
cantly larger for 3d (28.7 Hz) than for the cis-com-
plexes 3a,c (19 and 18 Hz) but it is comparable
with those of mms-fNi^-ZP^P^ö-rB^Cö^O^]
(30.5 Hz) [14] and even the monochelate com-
plexes ?rafts-[NiMe(2-RR'P-arylO)(PMe3 )] (22 -
26 Hz) [14],
\
But
Distinction of cis- and trans-isomers in solution
Whereas unsymmetrical cis- and trans-2-
phosphinophenolato nickel phosphine complexes
N(13C-231P2) shows the opposite trend and is
can be easily distinguished by the grossly differ- smaller for 3d (46.8 Hz), frans-[Ni(2-/Pr2P-4 ,6-
ent two-bond 3lP3lP-coupling constants (cis 70 -
rBu2C6H20 )2](42.6 Hz) and trans-[N\Me(2-RRT-
90 Hz [6 , 15, 16], trans ca. 300 Hz [8, 14]) the arylO)(PMe3)] (41 -49 Hz) [14] than for the cis-
pattern for symmetrical cis- and fra/w-square pla- complexes 4a-c (55.8 -61.2 Hz). The latter effect
nar isomers is usually very similar. Pseudo-triplets
were found since the intensity of the outer bands
which are different for the isomers is too low. A
comparison of the multinuclear NMR data of 3a-d
with those of related 2-phosphinophenolato nickel
is observed on a smaller scale also for the carbon
atoms C-6 (trans N « 7 -9 Hz, cis N & 13 -14 Hz)
and C-4 (trans N « 4 -7 Hz, cis N « 7 - 8 Hz)
in the other ortho- and the /?ara-position relative to
oxygen and it reflects the different donor-acceptor
complexes [6, 14, 15] indicates, however, that the interplay in trans- and c/s-complexes with opposite
coordination shifts AS = 6(3) - 6(1) of 31P and of P,P / 0,0- or P,0 arrangements. The higher A<$3IP
13C-1 nuclei as well as the 13C-31P couplings N = \J
/| of C-l and C-2 (Table I) possess high diagnos-
values of cis- as compared to frans-isomers may be
attributed to stronger donor interactions with nickel,
tic value for the distinction of cis- and /rans-square due to more ionic character ofthe trans-Ni-O bonds,
+
planar bis(phosphinophenolato)nickel complexes.
The phosphorus coordination shifts of cis-
[Ni(Ph2P-arylO)2]species were found in the region
Z\63IP = 62 -70 with the 6-rm-butyl derivatives
3a,b at the upper end, those of alkylphenylphos-
phino derivatives [Ni(AlkPhP-arylO)2] (Aik = Me,
/Pr) with higher donor and lower acceptor strength
atphosphorus atnoticeably higher values Z\6(31 P) =
73 -78. In contrast, the coordination shifts of trans-
[Ni(2-rBuPhP-4-MeC6H30)2] (A63]P = 43 [15])
and also of the more P-basic trans-[N\(2-iPr2P-
4,6-röu2C6H20)2](zA631P = 62 [14]) are markedly
whereas the higher Af(13C-231P2) values may be in-
terpreted in terms of a strengthened 7r-back bonding
in the P-Ni bonds, enforced by the electron donation
from trans-oxygen atoms. The strong influence of
the acceptor strength at phosphorus on ‘/pc-2 is un-
derlined by decreasing coupling in the order PfbP
> AlkPhP > Alk2P and the very low one-bond cou-
pling if back-bonding is not possible, e. g. lJpc-2 =
6 Hz ofthe recently published d°-transition metal 2-
phosphinophenolato complex [/^-CpTiCL^-PfbP-
6-/BuC6H30)] [17],
The influence of P-substituents in cis-3a-c on
lower. This allows the conclusion that 3a-c pre- _A631P and /V(13C-23IP2) can be separated from
fer a cis-, the more bulky and P-basic rm-butyl- the influence of a different geometry by opposite
phenylphosphino substituted complex 3d, however, trends of the two values and smaller effects. In the
a trans-square planar configuration in solution. This alkylphenylphosphino complex 3c zA631P is larger
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1238
J. Heinicke et al. ■Formation of /7’-P-(2 -Phosphinophenol)Ni(0 )(PMe3)3
C37
C121
Fig. 1. Molecular structure of (S,R)-3c; selected distances [A] and angles [°]: Nil-01 1.869(10), Nil-02 1.890(10),
Nil-Pl 2.157(4), Nil-P2 2.166(5), 01-C6 1.31(2), C6-C1 1.40(2), Pl-Cl 1.79(2), P1-C18 1.82(2), P1-C15 1.828
(14), C5-C6 1.41(2); 01-Nil-P2 170.3(3), 02-Nil-PI 171.2(4), 02-Nil-01 85.0(5), PI-Nil-P2 102.9(2), 0 1-Ni1-PI
86.4(3), C6-01-Nil 122.3(11), 01-C6-C1 120(2), C6-C1-PI 111.6(12), C2-C1-P1 125.5(14), Cl-Pl-Nil 99.7(5),
C1-P1-C15 109.0(7), C1-P1-C18 107.4(8), C18-P1-C15 106.6(7), 01-C6-C5 122(2), C6-C5-C7 120(2), C4-C5-C7
122(2), C4-C5-C6 118(2), C3-C4-C5 122(2).
3d, however, are at variance with the properties of
the other fra^s-complexes which form less soluble
whereas /V(13C-231P2) is smaller than in 3a or 3b.
The pattern of the proton multiplets of H-3 and the
diastereotopic Me groups (N larger for downfield green solids suggesting an alternative c/s-geometry
than for up-field Me groups) of the isopropylphos- in the solid state. This was verified by the crystal
structure analysis of 3d (Fig. 1). Interestingly, there
phino derivatives cis-3c and fra«.s-[Ni(2-/Pr2P-4 ,6-
rB ^C ö^O ^] [14] wasfound tobe different forcis- are considerable differences as compared with the
cis-structure of 3c (Fig. 2) investigated for com-
(“filled in” multiplets) and trans-geometry (doublet
of pseudotriplets).
parison.
The preference for the cis- or rra/w-arrangement
of the rigid 2-phosphinophenolato ligands depends
on the steric demand and/oron the basicity ofthe 2-
phosphino substituents. Two tert-buty\ or isopropyl
groups at phosphorus favor the formation of trans-
complexes as seen for mms-[Ni(2-rBu2PQ,H4 0 )2]
[9] and trans-[Ni(2-iPr2P-4,6-tBu2C6H20)2] [14].
The a-branched alkylphenylphosphinophenolato
complexes [Ni(2-AlkPh-4-MePC6H3 0 )2] (Aik =
tBu, /Pr) [6, 15, 18] were found to be borderline
Crystal and solid state molecular structures of 3c
and 3d
Crystals of compound 3d are monoclinic, space
group C2/c, with eight molecules in the centrosym-
metric unit cell. S,S and R,R molecules are built
up with two pairs of enantiomeric ligands. The
bulky tert-butyl groups are in anti-positions, thus
reducing sterical hindrance. The Pl-Ni-P2 angle
is widened to 107.06(8)°, the 01-Ni-02 and Ol-
cases, where replacement of a rm-butyl by an iso- Ni-Pl/02-Ni-P2 angles are diminished to 85.6 and
propyl group causes a switch from the trans- to the 84.45/85.45( 14)°, respectively, and the planes ofthe
two five-membered rings (PI/O 1/C1/C2/Ni 1 and
cis-structure. The NMR spectra of 3c and 3d bear-
ing additional bulky substituents in o-position to P2/02/C25/C26/Nil) are twisted by an angle of
22.3°. The deviation of nickel from the “best plane”
of P1/01/P2/02 is 0.036(1) A.
the oxygen atom confirm a similar behavior in solu-
tion. The brown color and thehigh solubility of solid
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1239
J. Heinicke et al. ■Formation of/7l-P-(2 -Phosphinophenol)Ni(0 )(PMe3)3
Fig. 2. Molecular structure of (5,5j-3d; selected distances [A] and angles [°]: Nil-01 1.878(4), Nil-02 1.874(4),
Ni 1-PI 2.172(2), Nil-P2 2.174(2), Ol-Cl 1.331(6), C1-C2 1.412(8), P1-C2 1.809(6), P1-C19 1.814(6), P1-C15
1.880(7), C1-C6 1.420(8); 01-Nil-P2 162.4, 02-Nil-Pl 164.7(2), 02-Nil-01 85.6(2), Pl-Nil-P2 107.06(8), 01-
Nil-Pl 84.45(14), C l-01-Nil 120.4(4), Ol-Cl-C2 120.5(6), Cl-C2-P1 108.8(5), C3-C2-P1 129.3(5), C2-Pl-Nil
99.7(2), C2-P1-C15 105.2(3), C2-P1-Cl9 106.8(3), Cl 9-PI-Cl5 108.7(3), Ol-Cl-C6 121.1(6), C1-C6-C7 120.5(6),
C5-C6-C7 122.8(6), C5-C6-C1 116.7(6), C4-C5-C6 125.7(7).
The triclinic crystals of3c contain four molecules
in the centrosymmetric unit cell (space group Pi).
The two independent molecules per asymmetric
cw-bis(chelates). The P-Ni-O and 01-Ni-02 angles
are only slightly diminished (1-3°) as compared to
[Ni(2-/PrPh-4 -MePC6H30 )2].Thedistortions in the
unit are very similar. Surprisingly the isopropyl and phenyl rings by the 4- and 6-terf-butyl groups are
phenyl groups are arranged each in ^/i-position (RS much larger. One of the terr-butyl groups of 3d and
and SR configuration) with a nearly staggered ar- all tert-butyl groups of 3c show rotational disorder
rangement of the isopropyl (torsion angle C15-P1- around the C-C axis as shown in Fig. 1.
P2-C38 20.3°) and phenyl groups (torsion angle
C18-P1-P2-C41 21.0°) which is facilitated by the
lack of a third substituent at the a-carbon atoms
C15 and C38. The two five-membered rings show
different distorsions. Whereas the deviation of Ni
from the plane P1/P2/01/02 is only 0.009(2) A, the
deviations ofPI and P2 from thebest planes ofring 1
and ring 2 are 0.018 and 0.14 A, respectively. The
dihedral angle of these planes (11.3°) is consider-
ably smaller than for 3d but noticeably larger than
Experimental Section
General procedures and materials
Handling of air-sensitive materials and all reactions
were conducted under an atmosphere of purified argon
using standard vacuum or Schlenk techniques. Solvents
were dried and kept under argon and freshly distilled
before use.
Tetrakis(trimethylphosphine)nickel(0) [19], N,N-di-
allylanilin(trimethylphosphine)nickel(0) [20] and the 2-
phosphinophenols la [12a] and lb [21] were prepared
according to known procedures. The syntheses of lc and
Id [12a] were improved as given below. Infrared spectra
were recorded on a Nicolet Impact 400 FTIR spectrom-
eter, NMR spectra on Bruker AM200, Bruker WM 300
or Bruker ARX 300 multinuclear Fourier transform spec-
in cis-[Ni(2-iPrPh-4-MePC6H30)2] (0
= 7.1°) [6 ]
with tfnr/-positioned isopropyl and phenyl groups.
The reason of the different structures is not clear.
The 6-terf-butyl groups, exerting a strong influence
on the conformation of O-substituted 2-phosphi-
nophenols, have rather low steric importance in
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1240
J. Heinicke et al. ■Formation of ry'-P-(2 -Phosphinophenol)Ni(0 )(PMe3)3
trometers. Shift references are tetramethylsilane for 'H
and l3C, and H3PO4 (85%) for 11P. For resonances which
are part of an AXX' spin system (X,X' = ’’P) vc and r
denote “virtual coupling” and a triplet pattern of the A-re-
sonance,/V= |7+/|. Atom numberings in theassignments
correspond to numbers according to the nomenclature of
Torr), and the residue was extracted with hot methanol
and recrystallized to yield 6.6 g (39%) of Id.
Analysis for C24H35OP (370.51)
Calcd C 77.80 H 9.52 P 8.36%,
Found C 77.89 H 9.35 P 8.39%.
31P (6 -18.8), 'H and 13C NMR data in CDCI agree
3
phosphinophenols, i, o, in and p denote the positions in
with those given in [12a],
phenyl substituents. Elemental analyses were performed
in the microanalytical laboratory of the TUD using a CHN
240A instrument (Perkin Elmer).
{4,6-Di-tert-butyl-2-(diphenylphosphino)phenol[P]}-
tris(trimethylphosphine)nickel(0) (2a)
rac-4,6-Di-tert-butyl-2-(isopropylphenylphosphino)-
770 mg (2.04 mmol) ofla was added at -78 °C to a
solution of Ni(PMe3)4 (740 mg, 2.04 mmol) in pentane
(50 ml). The resulting yellow solution was stirredfor 16h.
Removal of the solvent and of all volatiles afforded 2a as
a waxy yellow solid. IR (nujol): £> = 956 st, 933 sst. -
phenol(lc)
54 ml of an 1.6 N solution of n-butyllithium
(86.4 mmol) in hexane was added with cooling to a solu-
tion of 2-bromo-4,6-di-f-butylphenol (12.7 g, 43.1 mmol)
in ether (90 ml). After stirring for 3 h at room temper-
ature 8.06 g (43.1 mmol) of /PrPhPCl was added and
the mixture was stirred overnight. Then the reaction was
quenched by addition of 2 ml of glacial acetic acid.
Volatiles were removed in vacuo and the residue was ex-
tracted with ether. Ether was evaporated in vacuo and the
product of colorlesslc, m. p. 64 -65 °C, was crystallized
from methanol, 9.2 g (60%).
'H NMR (300 MHz, C6D6):
6 = 0.76 (s, 27H, PMe3),
0.79 (s, 9H, CMe3), 1.30 (s, 9H. CMe3), 6.33 (dd. 47HH=
2.3, 3/ph = 7.1 Hz, 1H, H-3), 6.76 (m, 7H, Ph, H-5),
7.19 (m, 4H, Ph), 10.5 (d qua, 47PH= 8.0, 6JPH= 2.4 Hz,
1H, OH). - l3C NMR (75.5 MHz, C6D6): <5= 23.6 (“qui”,
average line distance « 9.1 Hz, PMe3), 30.5 (CMe?,), 31.7
(CMe.,), 32.3 (CMe3), 34.5 (CAf<?3), 122.3 (d qua, ]JPC
29.0, 3yPc = 6.1 Hz, C-2), 124.4 (C-5), 128.0 (d, V PC =
9.2 Hz, C-m), 128.3 (C-p), 128.4 (C-3), 133.0 (d, 2JPC
=
=
15.3 Hz, C-o), 134.9 (C-6), 140.2 (d, 3/ PC= 3.0 Hz, C-4),
141.8 (d qua, 1JPC = 24.4, VPC = 8 Hz, C-i), 158.2 (d,
2J pc = 13.7 Hz, C-l). - 31P NMR (81 MHz, d8-THF):
Analysis for C23H33OP (356.48)
Calcd C 77.49 H 9.33 P 8.69%,
Found C 78.32 H 9.40 P 8.15%.
6
= -24.7 (d, 2JPP = 33.4 Hz, PMe3), 13.1 (qua, 27PP =
'H NMR (300 MHz, dg-THF):
6 = 0.94 (m, 3H, Mea),
33.4 Hz, P-2); impurity at -21.0 (br s).
1.06 (m, 3H, Meb), 1.23 (s, 9H, CMe3), 1.40 (s, 9H,
CMe3), 2.49 (m, 1H, CH), 3.27 (s, 1H, OH), 7.19 (m,
1H, H-3), 7.28 -7.32 (3H, Ph), 7.50 -7.56 (m, 3H, H-
5, Ph). - l3C NMR (75.5 MHz, dg-THF): 6 = 17.5 (d,
2J pc = 15.2 Hz, Me), 18.5 (d, 2J PC = 20.5 Hz, Me), 24.2
(d, Vpc = 4.3 Hz, CHMe2), 28.2 (CMe3), 30.0 (CMey),
33.2 (CMe3), 33.9 (CMe?), 119.4 (d, '/PC= 3.4 Hz, C-2),
124.3 (C-5), 126.1 (C-3 or C-p), 127.2 (d, V PC= 7.3 Hz,
C-m), 127.5 (C-p or C-3), 132.0 (d, 2JPC= 18.2 Hz, C-o),
134.0 (C-6), 135.6 (d, '7PC = 7.9 Hz, C-i), 140.3 (C-4),
156.0 (d, I/pc = 21.0 Hz, C-l). - 3IP NMR (81 MHz,
cis-Bis{4,6-di-tert-butyl-2-(diphenylphosphino)-
phenolato[0,P]}nickel(II) (3a)
Dry oxygen (50 ml, 2.23 mmol) was introduced into a
cold (-78 °C) solution of Ni(PMe3)4 (430 mg, 1.18 mmol)
and la (831 mg, 2.13 mmol) in THF (70 ml). Within
16 h the colorless solution turned via red-orange to dark
red. The solvent was removed in vacuo, the residue was
washed with ether and then extracted with THF to afford,
on cooling, 520 mg (50 %) of red crystals of 3a, m. p. >
220 °C.
d8-THF):
6
-23. (NMR data in CDCI [12a]).
3
Analysis for C52H6(,Ni02P2 • 2 THF (981.22)
Calcd C 73.45 H7.81 P 6.31%,
Found C 73.98 H 7.65 P6.95%.
rac-4,6-Di-tert-butyl-2-(tert-butylphenylphosphino)-
phenol(Id)
'H NMR (300 MHz, dg-THF): 6=1.11 (s, 9H, CMerf,
1.46 (s, 9H, CMei), 6.61 (m vc, 47Hh ~ 3, VPH« 10 Hz,
1H. H-3), 7.15 (m, 5H. H-5, H-o,m), 7.32 (m, 2H, H-p),
A solution of 2-bromo-4,6-di-r-butylphenol (13.1 g,
45.9 mmol) in ether (300 ml) was refluxed with NaH
(1.1g, 45.8 mmol) for 8 h and stirred for 1d at 20 °C, fol-
lowed by addition of 29 ml of a 1.6 N solution of /?BuLi
in ether. After 3 h, 9.2 g (45.9 mmol) of /BuPhPCl was
slowly added at -40 °C. The mixture was stirred for 19 h,
and 3 ml (52 mmol) of glacial acetic acid was added. Af-
ter filtration the volatiles were removed in vacuo (10“~
7.45 (m, 4H, Ph). - l3C NMR (75.5 MHz, dg-THF):
6 =
29.7 (CMei), 32.0 (CMe*), 34.6 (CMe3), 36.0 (CMe3),
118.8 (r, N = 61,2 Hz, C-2), 125.0 (C-5), 128.1 (C-3),
129.3 (t , N = 10.6 Hz, C-m), 130.8 (t, N = 49.1 Hz,C-/),
131.2 (C-p), 134.0 (t,N= 10.6 Hz, C-o), 137.6 (r, W «
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J. Heinicke et al. •Formation of /71-P-(2 -Phosphinophenol)Ni(0 )(PMe3)3
1241
8 Hz, C-4), 138.1 (r,
N
«
14 Hz, C-6), 173.4 (r,
N =
(CMe3), 111.6 (r,
3 and C-5), 127.8 (r,
45.8 Hz, C-0, 129.7 (C-p), 131.3 (r,
134.4 ( t , N a Hz, C-4), 136.1 (r, N = 12.2 Hz, C-6),
= 18.3 Hz, C-l). - 3IP NMR (121.5 MHz,
= 52.
N
= 54.9 Hz, C-2), 124.7, 126.2 (C-
18.9 Hz, C-l). - 3IP NMR (81 MHz, d8-THF):
6
=41.4.
N
= 9.2 Hz, C-m), 129.1 ( t ,
N =
N
= 9.2 Hz, C-o),
1
cis-Bis{6-tert-butyl-4-methyl-2-(diphenylphosphino)-
173.3 (r,
dx-THF):
N
phenolato[0,P]}nickel(II) (3bj
6
Ni(PMe3)4 (1.0 g, 2.76 mmol) and lb [21] (1.92 g,
5.51 mmol) were dissolved in THF (70 ml), and dry oxy-
gen (50 ml, 2.23 mmol) was introduced at -78 °C. The
resulting orange solution was stirred for 16h at room tem-
perature, the solvent was removed in vacuo and 1.08 g (47
%) of red 3b, m. p. > 220 °C, was obtained by extraction
of the residue with ether and crystallization.
rac-cis-Bis{4,6-di-tert-butyl-2-(tert-butylphenyl-
phosphino)phenolato[0,P]}nickel(II) (3d)
Dry oxygen (50 ml, 2.23 mmol) was introduced at
-78 °C into a solution of Id (1.76 g, 4.75 mmol) and
Ni(PMe3)4 (860 mg, 2.37 mmol) in THF (70 ml) causing
a color change to red. After stirring for 16 h at room
temperature the volatiles were removed in vacuo. The
residue was washed with a small amount of pentane and
extracted with ether to afford 1.40 g (74%) of 3d as small
brown crystals, m. p. > 220 °C.
Analysis for C46H48Ni02P2 • 1THF (825.63)
Calcd C 72.74 H 6.84 P7.50%,
Found C 71.67 H6.31 P7.96%.
'H NMR (300 MHz, d8-THF):
b = 1.41 (s,9H,CA/e3),
2.01 (s, 3H, 4-Me), 6.39 (vc, 1H, H-3), 6.86 (br s, 1H,
Analysis for C^HösNiChPi (797.83)
Calcd C 72.26 H 8.59 P7.76%,
Found C 71.65 H 8.54 P8.10%.
H-5), 7.11 (m, 4H, Ph), 7.31 (m, 2H, H-p), 7.44 (m, 4H,
Ph). - 13C NMR (75.5 MHz, d8-THF):
27.9 (CMei), 33.8 (s, CMe3), 117.8 (r, N = 60 Hz, C-2),
122.1 (r, /V « 8 Hz, C-4), 126.8 (C-5), 127.4 (r,
9.2 Hz, C-m), 128.7 (r, = 42.3 Hz, C-i), 129.3 (C-p),
130.0 (C-3), 132.0 (r, = 10.5 Hz, C-o), 136.9 (r,/V «
14 Hz, C-6), 171 (t,C-1).-3iPNMR(81 MHz, d8-THF):
6 = 18.8 (4-Me),
1H NMR (300 MHz, d8-THF): 6 = 1.14 (s, 9H, CMei),
N
=
1.24 (s, 9H, CMe3), 1.48 (r,
N = 14.9 Hz, 9H, PCMe3),
N
7.07 (d, 47hh = 2.4 Hz, 1H, H-5), 7.28 (m, 1H, H-3), 7.49
(m, 3H, Ph), 8.31 (m, 2H, Ph). - l3C NMR (75.5 MHz, d8-
N
THF):
b = 28.1 (PCMey), 29.6 (CMe,), 31.5 (CMe3), 33.9
6
= 40.7.
(CMe3), 34.8 (d, 1JPC = 11.3 Hz, PCMe3), 35.0 (CMe3),
rac-cis-Bis{4,6-di-tert-butyl-2-(isopropy!phenyl-
phosphino)phenolato[O,P]}nickel(II) (3c)
115.4 (r,
128.6 (r,
N
N
= 46.8 Hz, C-2), 126.7, 126.8 (C-3 and C-5),
= 9.1 Hz, C-m), 130.3 (C-p), 130.8 (r,
N
=
N
=
a) Reaction of crude lc and Ni(PMe3)4 followed by
partial air oxidation gave 3c. Single crystals were grown
from aTHF solution.31P NMR (121.5 MHz, d6-acetone):
6 = 47.5. 'H- and l3C NMR data agree with those given
below.
33.2 Hz, C-i), 134.6 (t, N= 11.3 Hz, C-o), 135.9 (r,
« 4 Hz, C-4), 138.6 (r, « 7 Hz, C-6), 173.5 (r,
N
N
28.7 Hz, C-l). - 31P NMR (81 MHz, d8-THF):
6 = 35.2.
Crystal structure analysis
b) A solution of lc (5.81 g, 16.3 mmol) in THF
(50 ml) was added at room temperature to a solution of
N,N-diallylanilin-(trimethylphosphine)nickel(0) (2.51 g,
8.15 mmol) [20] in THF (30 ml). The resulting red mix-
ture was allowed to stand for 2 d. Then all volatiles were
removed in vacuo. The red residue was dissolved in ether
/ pentane (1:2). From this solution 4.75 g (76%) of red
cubic crystals of 3c were obtained which on drying in
vacuo loose solvent to form an orange-red powder, m. p.
261 °C (dec.).
3c. A crystal was sealed under argon into a glass
capillary and mounted on a Siemens R3m diffractome-
ter which used graphite monochromated MoKa radia-
tion 0.71073 A. Lattice parameters were refined from
25 centered reflections. Intensities were collected (u:-2
9
scans) and LP and absorption (psi-scans) corrections ap-
plied. The structure was solved by direct and conventional
Fourier methods. Full-matrix least-squares refinement are
based on F2and 898 parameters. All non-hydrogenatoms,
except the butyl carbon atoms which were treated with
a split model, were refined anisotropically. Hydrogen
atoms were refined with a riding model in idealized posi-
tions. All butyl groups show disorder of the CH3groups
by rotation along the common C-C axis. Positions C12-
C14, C35, C36, and C81-C83 of the second independent
molecule were refined with a split model and half oc-
cupation each. Some diffuse electron density in the final
.IF map could not be assigned properly but may result
from enclosed ether solvent. 3d. Crystal mounting and
Analysis for C46H64Ni02P2 (769.62)
Calcd C 71.79 H 8.38 P 8.05%,
Found C 71.72 H 8.05 P 8.18%.
'H NMR (300 MHz, d8-THF):
6 = 0.92 (m, 6H,
CHMea), 1.23 (s, 18H, CMe^), 1.33 (m, 6H, CHMeb),
1.45 (s, 18H, CMe3), 2.39 (br m, 2H, C//Me2), 6.46 (m,
2H, H-3), 7.13 (m, 2H, H-5), 7.18-7.19 (m, 2H, Ph), 7.46-
7.61 (m, 8H, Ph). - l3C NMR (75.5 MHz, d8-THF):
15.1 (br, CHMe), 17.7 (br, CHMe), 23.2 (r, = 27.3 Hz,
CHMe2), 27.7 (CMe^), 30.2 (CMe3), 32.6 (CMe3), 34.0
6 =
N
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1242
J. Heinicke et al. ■Formation of r/]-P-(2 -Phosphinophenol)Ni(0 )(PMe3)3
Table II. Crystallographic data of compounds rac-3c and rac-3d.
rac-3c
rac-3d
Empirical formula
Molecular mass
Temperature [K]
Crystal system
C48H68NiO.PT
797.67
293 (2)
Monoclinic
C2/c
28.702 (9)
16.933 (4)
21.747 (5)
C46H64NiO.P2
769.62
293 (2)
Triclinic
Space group
Unit cell dimensions
Pi
15.790 (4)
18.686 (6)
20.385 (5)
109.68 (2)
94.76 (2)
114.15(2)
4994 (2); 4
1.024
0.482
1656
0.40 x 0.25 x 0.10
2.20 to 22.55
a
[A]
b[k]
[A]
a [ °
c
]
113.63(2)
ß[°]
7 [°]
V
[A ] ; Z
9683 (4); 8
1.094
0.500
Density (calculated) [Mg/m3]
Absorption coefficient [mm-1]
F(000)
3440
Crystal size [mm]
0.30 x 0.21 x 0.20
2.23 to 26.07
0 < h < 35, 0 < k <20, -26 < I < 24
9631
9439 (Rm = 0.0646)
none
6 Range for data collection [°]
Limiting indices
-17 < /? < 5, -20 < k < 18, 0 < / < 21
10204
Reflexions collected
Independent reflexions
Absorption correction
Max. & min.transmission
Data / restraints / parameters
Goodness-of-fit on F2
10030 (/?int = 0.0557)
Psi-scan
0.759 and 0.884
10028/116/898
1.048
9437/31 / 510
1.018
Final
R indices [I > 2o{I)]
indices (all data)
R
R
1= 0.1033, wR2 = 0.2270
1= 0.2439, wR2 = 0.3094
R
R
1= 0.0700, wR2 = 0.1058
1= 0.2522, wR2 = 0.1533
R
Extinction coefficient
Largest diff. peak and hole
0.00018(3)
0.259 and -0.259 eA-3
0.0017(5)
1.041 and -0.347 eA-3
data collection as for 3c. No absorption correction. Struc-
ture solution and refinement (F2, 510 parameters) as for
3c. Butyl group at C35 refined with a split model and site
occupation factors of 0.76(2) for C361-C381 and 0.24(2)
for C362-C382. Pertinent crystal data for both structures
are given in Table II.
application to CCDC, 12 Union Road, Cambridge CB2
1EZ, UK [Fax: (internat.) + 44 (1223)336-033, E-mail:
deposit@ccdc.cam.ac.uk).
Acknowledgement
Financial support of this work by the Fonds der
Chemischen Industrie and the Deutsche Forschungsge-
meinschaft is gratefully acknowledged. Further we thank
Dr. M. K. Kindermann and B. Witt (Greifswald) for nu-
merous NMR experiments.
Crystallographic data (excluding structure factors)
have been deposited with theCambridge Crystallographic
Data Centre. Copies of the data [CCDC-120938 (3c),
CCDC-120939 (3d)] can be obtained free of charge on
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J. Heinicke et al. • Formation of /y1-P-(2 -Phosphinophenol)Ni(0 )(PMe3 )3
1243
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