Bis(amino)phosphines derived from N-phenylpiperazine and N-ethylpiperazine: Synthesis, Oxidation reactions, and molybdenum complexes

Article abstract of DOI:10.1080/15533174.2012.740709

Functionalized bis(amino)phosphines that are the type PhP(NR ₂)₂ (1,2) have been synthesized by treating PhPCl ₂ with N-phenylpiperazine or N-ethylpiperazine. Ligands react with aqueous hydrogen peroxide, elemental sulfur, or selenium to give the corresponding chalcogenides (3-8) in good yield. The molybdenum complexes of the bis(amino)phosphines (9,10) have been obtained. All of the compounds obtained in good yields and they were characterized by IR, NMR, microanalysis, and also quantum chemical calculations such as HOMO-LUMO energies, Mulliken charges, and dipole moment for compounds 1-8 and complex 9 were carried out by using B3LYP/6-31G(d,p), a version of the DFT method with standard Gaussian 09 software package program. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/15533174.2012.740709

This article was downloaded by: [Otterbein University]
On: 25 April 2013, At: 21:06
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Synthesis and Reactivity in Inorganic, Metal-Organic,
and Nano-Metal Chemistry
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/lsrt20
Bis(amino)phosphines Derived From N-
phenylpiperazine and N-ethylpiperazine: Synthesis,
Oxidation Reactions, and Molybdenum Complexes
Özlem Sarıöz a , Sena Öznergiz a & Fatma Kandemirli b
a Department of Chemistry, Faculty of Science-Arts, Niğde University, Niğde, Turkey
b Department of Chemistry, Faculty of Science-Arts, Kastamonu University, Kastamonu,
Turkey
Accepted author version posted online: 02 Nov 2012.Version of record first published: 28 Dec
2012.
To cite this article: Özlem Sarıöz , Sena Öznergiz & Fatma Kandemirli (2013): Bis(amino)phosphines Derived From N-
phenylpiperazine and N-ethylpiperazine: Synthesis, Oxidation Reactions, and Molybdenum Complexes, Synthesis and
Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:2, 185-195
To link to this article: http://dx.doi.org/10.1080/15533174.2012.740709
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to
anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation that the contents
will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should
be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims,
proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in
connection with or arising out of the use of this material.

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:185–195, 2013
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2012.740709
Bis(amino)phosphines Derived From N-phenylpiperazine
and N-ethylpiperazine: Synthesis, Oxidation Reactions,
and Molybdenum Complexes
1
1
2
¨
¨
Ozlem Sarıo¨z, Sena Oznergiz, and Fatma Kandemirli
1
˘
˘
Department of Chemistry, Faculty of Science-Arts, Nigde University, Nigde, Turkey
2Department of Chemistry, Faculty of Science-Arts, Kastamonu University, Kastamonu, Turkey
application as anticancer drugs, herbicides, and antimicrobial
agents, as well as neuroactive agents.[9]
Functionalized bis(amino)phosphines that are the type
PhP(NR2)2 (1,2) have been synthesized by treating PhPCl2 with N-
phenylpiperazine or N-ethylpiperazine. Ligands react with aque-
ous hydrogen peroxide, elemental sulfur, or selenium to give the
corresponding chalcogenides (3–8) in good yield. The molybdenum
complexes of the bis(amino)phosphines (9,10) have been obtained.
All of the compounds obtained in good yields and they were char-
acterized by IR, NMR, microanalysis, and also quantum chemical
calculations such as HOMO-LUMO energies, Mulliken charges,
and dipole moment for compounds 1–8 and complex 9 were car-
ried out by using B3LYP/6-31G(d,p), a version of the DFT method
with standard Gaussian 09 software package program.
Herein, we describe the synthesis of new bis(amino
)phosphine ligands and the corresponding bis(amino)phosphine
chalcogenides of the general formula PhP(E)(NR2)2 and their
molybdenum complexes. The compounds were fully character-
1
ized by IR, H NMR, and 31P NMR spectroscopic techniques,
and by elemental analysis. Quantum chemical calculations were
carried out by using B3LYP/6–31G(d,p), a version of the DFT
method that uses Becke’s three parameter functional (B3) and
includes a mixture of HF with DFT Exchange terms associated
with the gradient corrected correlation functional of Lee, Yang,
and Parr (LYP), in this paper.[13] The theoretical parameters were
calculated in gas phase by using Gaussian 09 software package
program.[14]
Keywords aminophosphines, oxidation, quantum chemical calcula-
tions, synthesis
INTRODUCTION
EXPERIMENTAL
The coordination and organometallic chemistry of phospho-
rus bearing ligands possessing one (or more) P-N bond(s) has re-
ceived some attention, especially of late.[1–7] Although they pos-
sess two potential donor atoms, their coordination compounds
involve almost exclusively the metal–phosphorus bond.[8] The
transition metal chemistry of aminophosphines is limited. This
is partly due to the sensitivity of the P(III)/N bonds toward acid
or base catalyzed hydrolysis during complexation reactions.[2]
Many aminophosphine ligands and their complexes have been
investigated in a number of catalytic processes.[5,9–12] The pres-
ence of P-N bidentate ligands enables many different and impor-
tant catalytic processes to occur including asymmetric hydrob-
oration, carbonylation of alkynes, Stille coupling, and asym-
metric hydrogenation of highly substituted alkenes to name a
few.[10] Some aminophosphines and derivatives have also found
Reactions were routinely carried out using Schlenk-line tech-
niques under pure dry nitrogen gas. Solvents were dried and
distilled prior to use. [Mo(CO)4(bipy)] was prepared according
to the literature procedures.[15] All other chemicals were reagent
grade, available commercially and used without further purifi-
cation. Melting points were determined on an Electrothermal A
1
9100 and are uncorrected. 31P-{ H} and 1H NMR spectra were
taken on Bruker UltraShield-400 spectrophotometer (Germany).
Infrared spectra were recorded on a Perkin Elmer FT-IR System
Spectrum BX (USA). Elemental analysis were performed in a
CHNS-932 (LECO, USA).
Preparation of PPh(NC4H8NC6H5)2 (1)
Triethylamine (2.3 mL, 16.59 mmol) and PhPCl2 (1.1 mL,
8.11 mmol) were sequentially added with stirring to a solution of
N-phenylpiperazine (2.5 mL, 16.37 mmol) in THF (20 mL). The
reaction mixture was stirred for 6 h and then filtered to remove
Et3N.HCl. The resulting solution was evaporated under reduced
pressure and the product extracted with diethyl ether at –78◦C.
The solvent was removed under vacuum to give a white solid of
the crude product, which was crystallized from CH2Cl2/diethyl
ether mixture (2:1) at 0◦C. Yield 2.87 g (82%). m.p.: 164–166◦C.
Received 26 October 2011; accepted 13 October 2012.
The authors are grateful to Research Foundation of The University
of Nig˘de (NUAF) for financial support.
¨
Address correspondence to Ozlem Sarıo¨z, Department of Chem-
istry, Faculty of Science-Arts, Nig˘de University, Nig˘de, Turkey. E-mail:
ozsarioz4@yahoo.com
185

¨ ¨
O. SARIOZ ET AL.
186
1
1H NMR (CDCl3, δ, ppm): 6.76.-7.30 (m, Ph, 15H), 3.25 (t, 0.95 (t, N-CH2-CH3, 6H). 31P-{ H} NMR (CDCl3, δ, ppm): 75.2
1
N-CH2, 8H), 3.05 (t, N-CH2, 8H). 31P-{ H} NMR (CDCl3, (s). Selected IR (KBr, cm–1): 906 (PN), 632 (PS), 1437 (PPh).
δ, ppm): 22.3 (s). Selected IR (KBr, cm–1): 917 (PN), 1438 Elemental Analysis: C18H31PN4S (366.50 gmol–1); Found (Re-
(PPh). Elemental Analysis: C26H31PN4 (430.52 gmol–1) Found quired): C, 58.83 (58.99); H, 8.39 (8.52); N, 15.12 (15.29); S,
(Required): C, 72.34 (72.53); H, 7.11 (7.26); N, 12.88 (13.01). 8.59 (8.75).
Preparation of PPh(NC4H8NC2H5)2 (2)
Preparation of PhP(Se)(NC4H8NC6H5)2 (7)
A similar procedure to that described in 1 was used. Yield
1
2.33 g (86%). m.p.: 197–198◦C. H NMR (CDCl3, δ, ppm):
Ligand 1 (1.06 g, 2.46 mmol) and grey Se (0.2 g, 2.53 mmol)
were refluxed in toluene (20 mL) for 6 h. The reaction mix-
ture was concentrated to ca. 1–2 mL in vacuo and diethylether
(20 mL) was added. The precipitate was filtered and dried in
air to yield 7. Yield 0.81 g (65%). m.p.: 157–158◦C. 1H NMR
(CDCl3, δ, ppm): 6.8–8.19 (m, Ph, 15H), 3.11 (m, N-CH2, 16H).
7.20–7.82 (m, Ph, 5H), 2.81 (t, N-CH2, 8H), 2.24 (q, N-CH2,
1
12H), 0.96 (t, N-CH2-CH3, 6H). 31P-{ H} NMR (CDCl3, δ,
ppm): 23.8 (s). Selected IR (KBr, cm–1): 920 (PN), 1435 (PPh).
Elemental Analysis: C18H31PN4 (334.44 gmol–1); Found (Re-
quired): C, 64.41 (64.64); H, 9.15 (9.34); N, 16.52 (16.75).
1
31P-{ H} NMR (CDCl3, δ, ppm): 78.2 (s, JPSe = 812.5 Hz).
Selected IR (KBr, cm–1): 910 (PN), 538 (PSe), 1438 (PPh).
Elemental Analysis: C26H31PN4Se (509.48 gmol–1) Found (Re-
quired): C, 61.13 (61.29); H, 5.98 (6.13); N, 10.86 (11.00).
Preparation of PhP(O)(NC4H8NC6H5)2 (3)
A THF solution (10 mL) of 1 (0.75 g, 1.74 mmol) and aque-
ous H2O2 (30% w/w, 0.2 mL) was stirred for 2 h at room tem-
perature. The reaction mixture was concentrated to ca. 1–2 mL
in vacuo and diethylether (20 mL) was added. The precipitate
was filtered and dried in air to yield 3. Yield 0.43 g (55%).
m.p.: 115–117◦C. 1H NMR (CDCl3, δ, ppm): 6.76–7.77 (m, Ph,
Preparation of PhP(Se)(NC4H8NC2H5)2 (8)
A similar procedure to that described in 7 was used. Yield
1
0.8 g (78%). m.p.: 184–186◦C. H NMR (CDCl3, δ, ppm):
15H), 3.50 (t, N-CH2, 8H), 3.37 (t, N-CH2, 8H). 31P-{ H} NMR
1
(CDCl3, δ, ppm): 8.4 (s). Selected IR (KBr, cm–1): 917 (PN),
1438 (PPh), 1172 (P = O). Elemental Analysis: C26H31PN4O
(446.52 gmol–1); Found (Required): C, 69.76 (69.93); H, 6.75
(7.00); N, 12.36 (12.55).
7.26–8.02 (m, Ph, 5H), 2.92 (t, N-CH2, 8H), 2.30 (q, N-CH2,
1
12H), 0.95 (t, N-CH2-CH3, 6H). 31P-{ H} NMR (CDCl3, δ,
ppm): 77.8 (s, JPSe = 818.30 Hz). Selected IR (KBr, cm–1): 906
(PN), 526 (PSe), 1437 (PPh). Elemental Analysis: C18H31PN4Se
(413.40 gmol–1); Found (Required): C, 52.13 (52.30); H, 7.34
(7.56); N, 13.36 (13.55).
Preparation of PhP(O)(NC4H8NC2H5)2 (4)
A similar procedure to that described in 3 was used. Yield
0.38 g (61%). m.p.: 118–119◦C. H NMR (CDCl3, δ, ppm):
1
Preparation of cis-[Mo(CO)4 {PPh(NC4H8NC6H5)2}2] (9)
Ligand 1 (0.76 g, 1.76 mmol) and [Mo(CO)4(bipy)] (0.32 g,
0.88 mmol) were refluxed in 20 mL CH2Cl2 for 4.5 h. The so-
lution was concentrated in vacuo, and the purple product was
precipitated with diethylether (30 mL). The residue was washed
with toluene (3 × 5 mL). Yield: 0.32 g (34%). m.p.: 151–153◦C
7.20–8.03 (m, Ph, 5H), 2.83 (t, N-CH2, 8H), 2.32 (q, N-
1
CH2, 12H), 0.95 (t, N-CH2-CH3, 6H). 31P-{ H} NMR (CDCl3,
δ, ppm): 15.8 (s). Selected IR (KBr, cm–1): 931 (PN), 1438
(PPh), 1171 (P = O). Elemental Analysis: C18H31PN4O (350.44
gmol–1); Found (Required): C, 61.52 (61.69); H, 8.75 (8.92); N,
15.76 (15.99).
1
(decomp). H NMR (CDCl3, δ, ppm): 7.0–7.8 (m. Ph, 30H),
1
3.35 (t, N-CH2, 16H), 3.09 (t, N-CH2, 16H). 31P-{ H} NMR
Preparation of PhP(S)(NC4H8NC6H5)2 (5)
(CDCl3, δ, ppm): 102.4. Selected IR (KBr, cm–1): 952 (PN),
1440 (PPh), 2008, 1913, 1864 and 1802 (CO). Elemental Anal-
ysis: C56H62P2N8O4Mo (1069.03 gmol–1); Found (Required):
C, 62.63 (62.92); H, 5.78 (5.85); N, 10.27 (10.48).
Ligand 1 (1.06 g, 2.46 mmol) and S8 (0.079 g, 2.46 mmol)
were refluxed in toluene (20 mL) for 6 h. The reaction mix-
ture was concentrated to ca. 1–2 mL in vacuo and diethylether
(20 mL) was added. The precipitate was filtered and dried in
air to yield 5. Yield 0.52 g (46%). m.p.: 182–184◦C. 1H NMR
(CDCl3, δ, ppm): 6.76–7.97 (m, Ph, 15H), 3.15 (t, N-CH2, 8H),
Preparation of cis-[Mo(CO)4 {PPh(NC4H8NC2H5)2}2]
(10)
1
3.09 (t, N-CH2, 8H). 31P-{ H} NMR (CDCl3, δ, ppm): 75.4
(s). Selected IR (KBr, cm–1): 912 (PN), 639 (PS), 1438 (PPh).
Elemental Analysis: C26H31PN4S (462.59 gmol–1); Found (Re-
quired): C, 67.33 (67.51); H, 6.62 (6.75); N, 11.92 (12.11); S,
6.76 (6.93).
A similar procedure to that described in 9 was used. Yield:
1
0.57 g (74%). m.p.: 137–139◦C (decomp). H NMR (CDCl3,
δ, ppm): 7.60–8.70 (m, Ph, 10H), 2.49 (t, N-CH2, 16H), 2.34
1
(q, N-CH2, 24H), 0.96 (t, N-CH2-CH3, 12H). 31P-{ H} NMR
(CDCl3, δ, ppm): 119.7. Selected IR (KBr, cm–1): 942 (PN),
1440 (PPh), 2008, 1896, 1866 and 1778 (CO). Elemental Anal-
ysis: C40H62P2N8O4Mo (876.86 gmol–1); Found (Required): C,
54.13 (54.79); H, 6.98 (7.13); N, 12.57 (12.78).
Preparation of PhP(S)(NC4H8NC2H5)2 (6)
A similar procedure to that described in 5 was used. Yield
1
0.25 g (28%). m.p.: 175–177◦C. H NMR (CDCl3, δ, ppm):
7.26–8.02 (m, Ph, 5H), 2.9 (t, N-CH2, 8H), 2.3 (q, N-CH2, 12H),

BIS(AMINO)PHOSPHINES DERIVED FROM N-PHENYLPIPERAZINE AND N-ETHYLPIPERAZINE
187
1437–1438 cm–1. In the IR spectra of the compounds, while the
υP = O vibrations are observed in very narrow range, the υP-N
vibrations are observed in relatively wide range, suggesting that
P(III)-N bonds are quite sensitive to the substituents attached
to them. The IR spectra of 3 and 4 show υP O vibration at
1172 for 3 and 1171 cm–1 for 4. υ(P S) vibration is observed
at 639 cm–1 for 5 and 632 cm–1 for 7, and υ(P Se) vibration at
533 for 7 and 526 cm–1 for 8, respectively.
Vibrational analyses have been reported for some important
functional groups. The computed vibrational wavenumbers for
some important functional groups (raw values) with together
experimental values are collected in Table 1.
The υ(PN) bands of compounds 1–8 have been calcu-
lated in the region 893–909 cm–1 with B3LYP/6–31G(d,p)
and 961–971 cm–1 with RHF/LANL2DZ method. The ν(PPh)
bands have been calculated in the region 1475–1478 cm–1 for
B3LYP/6–31G(d,p) and 1475–1477 cm–1 for RHF/LANL2DZ
method. The υP O bands have been calculated at 1203 cm–1 for
3 and 1226 cm–1 for 4 with B3LYP method and 1233 cm–1 for 3
and 4 with RHF/LANL2DZ method, respectively. The υ(P S)
vibrations have been assigned at 727 cm–1 and 726 cm–1 with
B3LYP method, and 743 cm–1 and 737 cm–1 for RHF/LANL2DZ
method while the υ(P Se) bands have been calculated at
596 cm–1 and 556 cm–1 for B3LYP method, and 598 cm–1
and 564 cm–1 for RHF/LANL2DZ method, respectively. The-
oretical harmonic frequencies as seen from Table 1 typically
overestimate observed fundamentals due to the neglect of me-
chanical anharmonicity, electron correlation. and basis set ef-
fects. The correlation coefficient between theoretical and ex-
perimental values was found 0.9888 for B3LYP and 0.9919 for
RHF/LANL2DZ method, respectively.
RESULTS AND DISCUSSION
Synthesis and Structure Determination of the Compounds
Earlier works had shown that primary and secondary
amines react with chlorophosphines in the presence of
a
tertiary amine base to form aminophosphines.[16,17]
The reactions of N-ethylpiperazine or N-phenylpiperazine
with dichlorophenylphosphine afford the corresponding
derivatives bis(amino)phospine PhP(NC4H8NC6H5)2 (1) and
PhP(NC4H8NC2H5)2 (2) in good yield. Synthesis of
bis(amino)phosphine ligands 1 and 2 and their oxidation re-
actions are shown in Figure 1.
The structure of compounds 1 and 2 were confirmed by
spectroscopic analysis. The 31P-{ H} NMR spectra of the
1
bis(amino)phosphines show singlets at 22.3 ppm for 1 and
23.8 ppm for 2. The absence of a signal at 160.2 ppm indi-
cates that no unreacted PPhCl2 remained.[18] The 31P NMR and
1H NMR spectra are consistent with the proposed structure.
In the IR spectra of the ligands, the υ(PN) vibration is tenta-
tively assigned to a very strong absorption at 917 cm–1 for 1
and 920 cm–1 for 2, respectively.[19,20] The υ(PPh) bands are ob-
served in 1438 cm–1 for 1 and 1435 cm–1 for 2, respectively.[21]
Oxidation of 1, 2 aqueous hydrogen peroxide, elemental sul-
fur and selenium formed to the corresponding oxides (3 and
4), sulfides (5 and 6), and selenides (7 and 8), respectively.
Oxidation of 1, 2 using aqueous H2O2 was very rapid even at
ambient temperature. However, the reaction with elemental sul-
fur or selenium had to be carried out at elevated temperatures,
because elemental sulfur and selenium are weaker oxidizing
agents than hydrogen peroxide, especially toward phosphorus
atoms with bulky phenyl groups. As is typical of P(V) = E
compounds, 31P chemical shifts of compounds 3–8 occurred in
the δ 8.4–78.2 ppm range, and the chemical shift region is quite
consistent with the literature for analogous derivatives.[22–26]
As indicated in the literature, coupling constants of 1JPSe 812.5
–818.3 Hz are often seen for E Se.[26] The 1H NMR spectra are
consistent with the proposed structure.
The structures of the oxidized derivatives (3 and 4), sulfides
(5 and 6), and selenides (7 and 8) were further confirmed by
using microanalysis, and found to be in good agreement with
the theoretical values.
The molybdenum carbonyl derivatives, cis-[Mo(CO)4(L)2]
(L PPh(NC4H8NC6H5)2, 9; L PPh(NC4H8NC2H5)2, 10)
were obtained by the displacement of bipyridine from the
[Mo(CO)4(bipy)]. The molybdenum carbonyl derivatives are
shown in Figure 2.
In the IR spectra of 3–8, the υ(PN) vibration is observed at
917 cm–1 (3), 931 cm–1 (4), 912 cm–1 (5), 906 cm–1 (6), 910 cm–1
(7), and 906 cm–1 (8). The ν(PPh) bands are observed in range of
E
N
N
N
N
R
R
N
N
N
R
R
Et N
2
H2O2/S8/Se
3
PhPCl2
H
N
N R
+
PhP
PhP
- 2 Et3N.HCl
N
1-2
3-8
1; R= C6H5
2; R= C2H5
3; E=O, R= C6H5, 4; E= O, R= C2H5
5; E=S, R= C6H5, 6; E= S, R= C2H5
7; E=Se, R= C6H5, 8; E= Se, R= C2H5
FIG. 1. Synthesis of bis(amino)phosphine ligands 1 and 2 and their oxidation reactions.

¨
¨
188
O. SARIOZ ET AL.
TABLE 1
Some experimental and theoretical (B3LYP/631G(d,p) and RHF/LANL2DZ) vibrational data (in cm−1) for aminophosphine
derivatives
υ
Compound
B3LYP 6–31G(d,p)
RHF LANL2DZ(d,p)
Experimental
PPh(NC4H8NC6H5)2 (1)
PN
PPh
PN
896
1475
897
969
1475
968
917
1438
920
PPh(NC4H8NC2H5)2 (2)
PPh
PN
1475
907
1475
971
1435
917
PhP(O)(NC4H8NC6H5)2 (3)
PPh
PO
PN
1478
1203
893
1477
1233
970
1438
1172
931
PhP(O)(NC4H8NC2H5)2 (4)
PhP(S)(NC4H8NC6H5)2 (5)
PhP(S)(NC4H8NC2H5)2 (6)
PhP(Se)(NC4H8NC6H5)2 (7)
PhP(Se)(NC4H8NC2H5)2 (8)
PPh
PO
PN
PPh
PS
PN
PPh
PS
PN
PPh
PSe
PN
1477
1226
900
1476
727
907
1477
726
1477
1233
965
1477
743
965
1476
737
1438
1171
912
1438
639
906
1437
632
904
1477
596
961
1477
598
910
1438
533
909
963
906
PPh
PSe
1477
556
1477
564
1437
526
1
plexes (ꢀδ). In the 31P-{ H} NMR spectra, 9 and 10 exhibit
singlets that show the expected low-field shifts relative to the
uncoordinated ligands [9: 102.4 ppm (ꢀδ = 80.1 ppm) and 10:
The molybdenum carbonyl derivatives, cis-[Mo(CO)4(L)2]
(9, 10) were characterized by IR, NMR, and elemental analy-
sis. Ligands bearing both amine and tertiary phosphine donors
should behave as monodentate ligand (via P or N) or biden-
tate ligand (via P and N). The P-N bond in aminophosphines
is essentially a single bond, so the lone pairs on nitrogen and
phosphorus are available for donor bonding toward metal atoms.
However, no examples have been synthesized where both P and
N have acted as donor atoms. It is only P that acts as the donor
atom. The phosphorus chemical shift for complexes indicates
P-M interaction due to the low coordination shift value of com-
119.7 ppm (ꢀδ = 95.9 ppm).[19] The 31P–{ H} NMR chemical
1
shifts of 9 and 10 are also within the expected range for struc-
turally similar complexes.[20] The phosphorus chemical shifts
for the complexes indicate P–Mo interaction. In the IR spectra
of the molybdenum carbonyl complexes, the υ(PN) vibration is
tentatively assigned to a very strong absorption at 952 cm–1 for
9 and 942 cm–1 for 10, respectively, which is shifted to higher
wavenumbers for 9 (ꢀυ = 35 cm–1) and 10 (ꢀυ = 22 cm–1)
compared with their free ligands.[19,20] The ν(PPh) bands are
observed in 1440 cm–1 for 9 and 10. The infrared spectra of the
complexes [Mo(CO)4L2] exhibit four intense υ(CO) absorp-
tions, in the carbonyl region (2008–1778 cm–1), characteristic
of the presence of cis-[Mo(CO)4] with C2v symmetry.[5,27–30]
The generation of [Mo(CO)4L] complexes may be used to as a
rapid “spot test” for the donor properties of new ligands. This
attribute has been recognized for many years, and an extensive
literature exists for these complexes, allowing ready comparison
with a variety of other phosphorus(III) ligands. The value υCO
has been used to evaluate the ligand electronic properties.[31]
The position of υCO for the molybdenum complexes 9 and 10
CO
OC
OC
L
L
Mo
CO
9)
L=PhP(NC2H4NC6H5)2
L=PhP(NC H NC H )
5 2
9-10
10)
2
4
2
FIG. 2. Proposed structures of cis-[Mo(CO)4(L)2] complexes.

BIS(AMINO)PHOSPHINES DERIVED FROM N-PHENYLPIPERAZINE AND N-ETHYLPIPERAZINE
189
TABLE 2
is shown in Table 2. It was found that in the molybdenum com-
plex 9 and 10 have similar υCO stretching frequency, indicating
that 1 and 2 have electronic properties.
Comparison of υCO of [M(CO)4L2]
Complex
υCO cm−1
cis- [Mo(CO)4
2008, 1913, 1864, 1802
2008, 1896, 1866, 1778
Theoretical Calculations
{PPh(NC4H8NC6H5)2}2] (9)
Quantum chemical calculations on compounds 1–9 were per-
formed with full geometrical optimizations by using standard
Gaussian 09 software package.[14] Geometrical optimization
were carried out with two different methods: ab initio methods
at the Hartree-Fock (HF) level, and density functional theory
cis- [Mo(CO)4
{PPh(NC4H8NC2H5)2}2] (10)
The molecular structure of compounds 1–8 and their atom
(DFT) with the B3LYP change-correlation corrected functional numbering calculated by B3LYP/6–31(d,p) level are shown in
by using 6–31G(d,p) basis sets.
Figure 3.
FIG. 3. Optimized structures of compounds 1–8 (color figure available online).

¨ ¨
O. SARIOZ ET AL.
190
atom, P-N bond length is shortened from 1.748 to 1.739 and
P-C bond length changing is not important, and Mo-P length is
found as 2.898 Å.
As seen in Table 3, the angle of N38P1N37 for compounds
1, 3, 5, 7 are 112.5◦, 101.7◦, 101.1◦, and 101.4◦; C18P1N38
100.6◦, 109.4◦, 108.2◦, and 108.5◦; C18P1N37 100.6◦, 104.0◦,
102.9◦, and 103.4◦. When aminophosphine 1 coordinated to
molybdenum, the angle of N38P1N37 changed from 112.5◦ to
104.4◦. The P37-Mo-P38 bond angle is 104.4◦ that is larger
than the ideal angle of 90◦ and Mo-C bond angle (C belongs to
CO group) is 88.2◦ and C-Mo-P is 84.2◦, and both are slightly
smaller than the ideal angle of 90◦. The molybdenum atom is
coordinated with two phosphorus atoms of the aminophosphine
ligands and four carbonyl groups in a slightly distorted octahe-
drally.
The energies of HOMO and LUMO for compounds 1–8 were
calculated using B3LYP/6–31G(d,p) method (Figure 5). High
values of EHOMO indicates a tendency of the molecule to donate
electrons to appropriate acceptor molecules, as electron donat-
ing ability of a molecule is related with EHOMO. The energies
of HOMO and LUMO for aminophosphines are higher than
the energies of HOMO and LUMO for aminophosphine chalco-
genides. When we move from O to Se, the energies of HOMO
and LUMO decreases.
Molecular orbital calculations were carried out to calcu-
late the molecular orbital coefficients of the HOMO and
the LUMO levels for compounds 1–8 to explain the coor-
dination of them on the metal. The HOMO electronic den-
sity distribution for compounds 1–8, are plotted in Figu–
re 6.
Phosphines are considered a soft, strong σ-donor, but a
relatively weak π-acceptor ligand in organometallic chem-
istry. However, the donor–acceptor properties are found to al-
ter depending on the nature of substituents on the phospho-
rus.[19] In molecular orbital theory (e.g., Hartree-Fock theory or
Huckel theory), Pearson emphasized that the hardness is given
Eq. 1.[33]
FIG. 4. Optimized structure of molybdenum complex 9 (color figure available
online).
The molecular structure of complex 9 calculated by
RHF/LANL2DZ is shown in Figure 4.
Optimized molecular structural parameters by B3LYP meth-
ods with 6–31G(d,p) basis set for compounds under study and
their electronic parameters are summarized in Tables 3 and 4.
The P1–N37 bond lengths for compounds 1, 3, 5, 7, 2, 4, 6, and 8
are 1.748 Å, 1.720 Å, 1.735 Å, 1.740 Å, 1.748Å, 1.721 Å, 1.737
Å, and 1.741 Å, respectively, in the calculations carried out with
RHF/LANL2DZ method and 1.721 Å, 1.700 Å, 1,713 Å, 1,717
Å, 1,720 Å, 1,698 Å, 1,711 Å, and 1,714 Å, respectively, in the
calculatons carried out with B3LYP/6–31G(d,p) method. P-N
bond lengths in aminophosphine chalcogenides are shorter than
P-N bond length in the aminophosphine. When we move from
Se to O, the P–N bond length is shortened. With an increase in
the electronegativity of the chalcogen atom, enhanced electron
transfer from nitrogen to chalcogen atom occurs, thus the P–N
bond length reduces further.[32] The P1–C18 bond lengths for
compounds 1, 3, 5, 7, 2, 4, 6, and 8 are 1.878 Å, 1.843 Å, 1.854
Å, 1.858 Å, 1.879Å, 1.844 Å, 1.855 Å, and 1.858 Å, respec-
tively, on the calculations carried out by using RHF/LANL2DZ,
so the shortest P1-C18 bond lengths are obtained in aminophos-
phine oxides (3 and 4). P-O, P-S, P-Se bond lengths for 3–8
are calculated as 1.583 Å for 3, 2.111 Å for 5, 2.275 Å for 7,
1.584 Å for 4, 2.113 Å for 6, and 2.277 Å for 8, respectively, for
RHF/LANL2DZ method. In morpholino series of compounds,
P-O bond length for (OC4H8N)3PO and P-Se bond length for
(OC4H8N)3PSe are 1.486 Å and 2.106 Å, respectively.[32 ] As
ꢀ
ꢁ
ELUMO − EHOMO
η =
[1]
2
Softness (S), which is the reciprocal of hardness, is a prop-
erty of molecules that measures the extent of chemical reactivity.
Softness value calculated with Eq. 2 for compounds 1, 3, 5, 7,
2, 4, 6, and 8 are 12,09, 12.48, 12.81, 12.86, 11.62, 11.48,
11.74, and 11.90, respectively. the softness of the molecule
increases with the increase in the atomic size: O < S <
Se.
ꢀ ꢁ
1
s =
[2]
η
Figure 7 provides Mulliken charge values of some atoms
seen in Table 5, when ligand 1 coordinated to the molybdenum for different aminophosphine derivatives that illustrates the

BIS(AMINO)PHOSPHINES DERIVED FROM N-PHENYLPIPERAZINE AND N-ETHYLPIPERAZINE
191
TABLE 3
Selected bond length calculated with RHF and B3LYP method for compounds 1, 3, 5, 7
1
3
5
7
B3LYP
RHF
B3LYP
RHF
B3LYP
RHF
B3LYP
RHF
Bond length (Å)
6-31G(d,p)
lanl2dz
6-31G(d,p)
lanl2dz
6-31G(d,p)
lanl2dz
6-31G(d,p)
lanl2dz
P1-N37
P1-N38
P1-C18
C18-C19
C18-C20
N37-C3
N37-C2
N40-C47
N38-C11
N38-C10
N39-C41
P1-E63
1,721
1,721
1,852
1,404
1,404
1,467
1,465
1,406
1,467
1,465
1,406
1.748
1.748
1.878
1.400
1.397
1.467
1.465
1.421
1.467
1.464
1.422
1,700
1,699
1,827
1,405
1,400
1,475
1,468
1,407
1,479
1,477
1,408
1,497
1.720
1.715
1.843
1.398
1.396
1.475
1.468
1.422
1.476
1.476
1.422
1.583
1,713
1,709
1,839
1,406
1,402
1,475
1,474
1,408
1,481
1,480
1,410
1,969
1.735
1.725
1.854
1.400
1.395
1.474
1.473
1.422
1.478
1.478
1.422
2.111
1,717
1,707
1,837
1,405
1,402
1,475
1,472
1,408
1,484
1,483
1,410
2,106
1.740
1.728
1.858
1.400
1.395
1.474
1.474
1.422
1.478
1.479
1.422
2.275
Bond angle (◦)
N37-P1-N38
N38-P1-C18
N37-P1-C18
E63-P1-C18
E63-P1-N38
E63-P1-N37
112,5
100,6
100,6
108.6
100.8
102.2
101,7
109,4
104
110,6
119,2
111,3
102.2
110.3
105.2
110.1
117.3
110.1
101,1
108,2
102,9
112,6
117,3
113,5
102.7
108.4
103.8
112.7
115.2
113.0
101,4
108,5
103,4
112,6
116,6
113,3
102.4
108.0
103.4
113.4
114.9
113.6
TABLE 4
Selected bond length calculated with RHF and B3LYP method for compounds 2, 4, 6, and 8
2
4
6
8
B3LYP
RHF
B3LYP
RHF
B3LYP
RHF
B3LYP
RHF
Bond length (Å)
6-31G(d,p)
lanl2dz
6-31G(d,p)
lanl2dz
6-31G(d,p)
lanl2dz
6-31G(d,p)
lanl2dz
P1-N37
P1-N38
P1-C18
C18-C19
C18-C20
N37-C3
N37-C2
N40-C47
N38-C11
N38-C10
N39-C41
P1- E63
1,720
1,720
1,853
1,405
1,405
1,467
1,467
1,468
1,467
1,467
1,468
1.748
1.748
1.879
1.399
1.399
1.469
1.473
1.470
1.473
1.469
1.470
1,698
1,696
1,828
1,405
1,403
1,479
1,480
1,169
1,475
1,469
1,468
1,497
1.721
1.715
1.844
1.398
1.396
1.481
1.481
1.471
1.479
1.472
1.471
1.584
1,711
1,706
1,840
1,406
1,402
1,481
1,482
1,469
1,475
1,475
1,468
1,971
1.737
1.726
1.855
1.399
1.395
1.483
1.482
1.472
1.478
1.477
1.471
2.113
1,714
1,704
1,838
1,405
1,402
1,484
1,485
1,469
1,475
1,473
1,468
2,109
1.741
1.729
1.858
1.400
1.395
1.483
1.482
1.472
1.478
1.478
1.471
2.277
Bond angle (◦)
N37-P1-N38
N38-P1-C18
N37-P1-C18
E63-P1-C18
E63-P1-N38
E63-P1-N37
112,7
100,5
100,5
109.5
101.5
101.5
101,9
109,2
100,9
11,1
110,9
119,2
103.8
110.1
105.2
110.1
110.4
117.0
101,2
108,2
102,9
113,3
112,8
117,3
103.0
108.2
103.9
112.8
112.9
115.1
101,6
108,5
103,4
113,1
112,6
116,5
102.7
107.8
103.4
113.4
113.6
114.8

¨
¨
192
O. SARIOZ ET AL.
TABLE 5
Selected bond length calculated with RHF method for molybdenum complex 9
Bond length (Å)
RHF lanl2dz
RHF lanl2dz
Bond angle (◦)
RHF lanl2dz
P1-N37
P1-N38
P1-C18
C18-C19
C18-C20
N38-C11
N38-C10
N39-C52
N37-C2
N37-C3
Mo1-C4
C4-O8
1.739
1.739
1.879
1.400
1.395
1.479
1.470
1.397
1.667
1.467
2.077
1.150
N40-C41
Mo1-C3
C3-O7
Mo1-C2
C2-O6
Mo1-C5
C5-O9
Mo-P1
4.423
2.004
1.558
2.026
1.153
2.074
1.150
2.898
2.831
Mo(CO)6
2.105
1.143
N37-P1-N38
N38-P1-C18
N37-P1-C18
PMoP
104.4
99.7
104
104.2
Mo1-P11
effect of varying groups on the phosphorus centre and the Mul- Mulliken charges calculated with RHF/LANL2DZ on phospho-
liken charge for aminophosphine derivatives calculated by using rus atom are 1.203 for free ligand and 1.366 for molybdenum
B3LYP/6–31G(d,p) and RHF(LANL2DZ) methods. The elec- complex 9 (Figure 7). The Mulliken charge on N37, C2, C3,
tronic distribution of compounds are very sensitive to changes N38, C20, and N39 atoms are more negative than those of free
atoms coordinated to phosphorus. The Mulliken charges on ligand.
phosphorus atom for compounds 1, 3, 5, and 7, are 0.612
Dipole moment for compounds 1, 3, 5, and 7 are
e¯, 1.116 e¯, 0.827 e¯, and 0.963 e¯, respectively. The Mulliken given in Table 6. The dipole moment of compound 1 is
charge of N37 atom bonded to phosphorus atom (Figure 7) is 1.10 D and for aminophosphine chalcogenides 3, 5, and
–0.560 e¯ for compound 1, –0.599 e¯ for compound 3, –0.588 7 are 3.24 D, 4.07 D, and 3.96 D. Dipole moment of
e¯ for compound 5, and –0.590 e¯ for compound 7. The Mul- aminophosphine is less than those of aminophosphine chalco–
liken charge on C18 atom bonded to phosphorus atom (Fig- genides.
ure 7) is –0,142 e¯ for compound 1, –0.153 e¯ for compound 3,
The P1-C18 NBO composition is 0.585 P1 (sp4.44d0.07) +
–0,123 e¯ for compound 5, and –0135 e¯ for compound 7. The 0.811 C18(sp2.43). So, there are 34.26% localization on P1 and
FIG. 5. HOMO, HOMO-1, HOMO-2, HOMO-3, HOMO-4, HOMO-5, LUMO, LUMO + 1, LUMO + 2, LUMO + 3, LUMO + 4, LUMO + 5 (au) energy
values for compounds 1–8 (color figure available online).

BIS(AMINO)PHOSPHINES DERIVED FROM N-PHENYLPIPERAZINE AND N-ETHYLPIPERAZINE
193
FIG. 6. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) and ESP of the molecules 1–8 (color figure
available online).

¨
¨
194
O. SARIOZ ET AL.
FIG. 7. Mulliken Charges of molecules 1–8 calculated with (a) B3LYP/6-31G(d,p) and (b) RHF/LANL2DZ (color figure available online).
TABLE 6
65.74% localization on C18 for P1-C18 bond, and 23.78%,
localization on P1 and 76.22% localization on N37 and N38
for P1-N37 bond and P1-N38 bond. This describes a polar P-
C and P-N bonds. Percent localization on P1 of P1-C18 for
aminophosphine chalcogenides is slightly more than those for
aminophosphine. As seen Table 7, P = E (O, S, Se) NBO com-
position bond in aminophosphine chalcogenides are (0.4945.
Dipole moment calculated with B3LYP/6–31G(d,p) for
molecules 1, 3, 5, and 7
Compound
Dipole moment (debye)
B3LYP 6-31G(d,p)
RHF lanl2dz
0.6727
1
3
5
7
1.0996
3.2440
4.0694
3.9634
sp2.45d0.05) P1 + (0.8692. sp1.71d0.01) O63, (0.6942. sp2.40d0.04
)
4.8029
5.2021
5.0889
P1+ (0.7198. sp4.49d0.02) S63, and (0.7246. sp2.52d0.02) P1+
(0.6892. sp5.94d0.06) Se63, so there are 24.45%, 48.19%, and
52.50% localization on P1.

BIS(AMINO)PHOSPHINES DERIVED FROM N-PHENYLPIPERAZINE AND N-ETHYLPIPERAZINE
¨
195
TABLE 7
9. Durap, F.; Biricik, N.; Gu¨mgu¨m, B.; Ozkar, S.; Ang, W.H.; Fei, Z.; Scopel-
liti, R. Polyhedron 2008, 27, 196–202.
P-C, P-N, and P-E (E = O, S, Se) NBO compositions
calculated with B3LYP/6–31G(d,p) for molecules 1, 3, 5, and 7
10. Slawin, A.M. Z.; Wheatley, J.; Wheatley, M.V.; Woollins, J.D. Polyhedron
2003, 22, 1397–1405.
11. Saluzzo, C.; Breuzard, J.; Pellet-Rostaing, S.; Vallet, M.; Le Guyader, F.;
Lemaire, M. J. Organomet. Chem. 2002, 98, 643–644.
12. Cheng, J.; Wang, F.; Xu, J.; Pan, Y.; Zhang, Z. Tetrahedron Lett. 2003, 44,
7095–7098.
Compound
1
(0.585. sp4.44d0.07)P1 + (0.811. sp2.43) C18
(0.4877. sp5.42d0.11) P1 + (0.8730. sp1.90) N37
(0.4877. sp5.42d0.11) P1+ (0.8730. sp1.90) N38
(0.5826. sp2.89d0.06) P1+ (0.8128. sp2.45) C18
(0.4990. sp3.16d0.09) P1+ (0.8666. sp2.39) N37
(0.4975. sp3.29d0.09) P1+ (0.8675. sp2.30) N38
(0.4945. sp2.45d0.05) P1 + (0.8692. sp1.71d0.01) O63
(0.6031. sp2.96d0.05) P1+ (0.7977. sp2.46) C18
(0.5167. sp3.24d0.07) P1+ (0.8562. sp2.53) N37
(0.5134. sp3.32d0.07) P1 + (0.8581. sp2.29) N38
(0.6942. sp2.40d0.04) P1+ (0.7198. sp4.49d0.02) S63
(0.6052. sp2.90d0.04) P1 + (0.7961. sp2.46) C18
(0.5200. sp3.21d0.07) P1+ (0.8542. sp2.66) N37
(0.5144. sp3.26d0.07) P1 + (0.8576. sp2.26) N38
(0.7246. sp2.52d0.02) P1+ (0.6892. sp5.94d0.06) Se63
13. Lee, C.; Yang, W.; Parr, R.G. Phys. Rev, B. 1988, 41, 785–789.
14. Frisch, M.J.; Trucks, G.W.; Schlegel, H.B.; Scuseria, G.E.; Robb, M.A.;
Cheeseman, J.R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G.A.;
Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H.P.; Izmaylov, A.F.; Bloino,
J.; Zheng, G.; Sonnenberg, J.L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda,
R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,
H.; Vreven, T.; Montgomery, J.A. Jr.; Peralta, J.E.; Ogliaro, F.; Bearpark,
M.; Heyd, J.J.; Brothers, E.; Kudin, K.N.; Staroverov, V.N.; Kobayashi,
R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J.C.; Iyengar,
S.S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J.M.; Klene, M.; Knox, J.E.;
Cross, J.B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann,
R.E.; Yazyev, O.; Austin, A.J.; Cammi, R.; Pomelli, C.; Ochterski, J.W.;
Martin, R.L.; Morokuma, K.; Zakrzewski, V.G.; Voth, G.A.; Salvador, P.;
3
5
7
¨
Dannenberg, J.J.; Dapprich, S.; Daniels, A.D.; Farkas, O.; Foresman, J.B.;
Ortiz, J.V.; Cioslowski, J.; Fox, D.J. , Wallingford, CT, Gaussian, Inc.
2009.
15. Stiddard, M.H. B. J. Chem. Soc. 1962, 4712–4715.
16. Hill, T.G.; Haltiwanger, R.C.; Prout, T.R.; Norman, A.D. Inorg. Chem.
1989, 28, 3461–3467.
CONCLUSIONS
17. Sarıo¨z, O.; Serindag˘, O.; Abdullah, M.I. Phosphorous, Sulfur Silicon Relat.
Elem. 2009, 184, 1785–1795.
18. Hessler, A.; Stelzer, O. J. Org. Chem. 1997, 62, 2362–2369.
19. Ku¨hl, O.; Blaurock, S.; Sieler, J.; Hey-Hawkins, E. Polyhedron 2001, 20,
111–117.
In conclusion, the new bis(amino)phosphine and their ox-
ides, sulfides, selenides, and molybdenum complexes have
been prepared. The compounds were characterized. Although
aminophosphines possess two potential donor atoms, their co-
ordination compounds involve the metal–phosphorus bond. The
coordination through phosphorus is attributed to the low basicity
of the amine nitrogen because of the P–N π interaction between
the phosphorus dπ and nitrogen pπ orbitals.
20. Zubiri, M.R.; Slawin, A.M. Z.; Wainwright, M.; Woollins, J.D. Polyhedron
2002, 21, 1729–1736.
¨
¨
21. Aydemir, M.; Durap, F.; Baysal, A.; Akba, O.; Gu¨mgu¨m, B.; Ozkar, O.;
Yıldırım, L. Polyhedron 2009, 28, 2313–2320.
¨
22. Biricik, N.; Durap, F.; Kayan, C.; Gu¨mgu¨m, B.; Gu¨rbu¨z, N.; Ozdemir,
˙
I.; Ang, W.H.; Fei, Z.; Scopelliti, R. J. Organomet. Chem. 2008, 693,
2693–2699.
23. Rudd, M.D.; Creighton, M.A.; Kautz, J.A. Polyhedron 2004, 23,
1923–1929.
REFERENCES
1. Burrows, A.D.; Mahon, M.F.; Palmer, M.T. J. Chem. Soc. Dalton Trans.
2008, 3615–3619.
2. Priya, S.; Balakrishna, M.S.; Mague, J.T. (2003) J. Organomet. Chem. 2003,
679, 116–124.
24. Kingsley, S.; Vij, A.; Chandrasekhar, V. Inorg. Chem. 2001, 40, 6057–6060.
25. Balakrishna, M.S.; Mague, J.T. Polyhedron 2001, 20, 2421–2424.
26. Burrows, A.D.; Kociok-Ko¨hn, G.; Mahon, M.F.; Varrone, M.C. R. Chimie
2006, 9, 111—119
3. Necas, M.; St, J.; Foreman, M.R.; Dastych, D.; Novosad, J. Inorg. Chem.
Commun. 2001, 4, 36–40.
27. Lindner, E.; Mohr, M.; Nachtigal, C.; Fawzi, R.; Henkel, G. J. Organomet.
Chem. 2000, 595, 166–177.
4. Liu, H.; Banderia, N.A. G.; Calhorda, M.J.; Drew, M.G. B.; Felix, V.;
Novosad, J.; Fabrizi de Biani, F.; Zanello, P. J. Organomet. Chem. 2004,
689, 2808–2819.
5. Gaw, K.G.; Smith, M.B.; Steed, J.D. J. Organomet. Chem. 2002, 664,
294–297.
28. Balakrishna, M.S.; Abhyankar, R.M.; Mague, J.T. J. Chem. Soc. Dalton
Trans. 1999, 1407–1412.
29. Balakrishna, M.S.; McDonald, R. Inorg. Chem. Commun. 2002, 5, 782–
786.
30. Thurner, C.L.; Barz, M.; Spiegler, M.; Thiel, W.R. J. Organomet. Chem.
1997, 541, 39–49.
31. Zubiri, M.R.; Clarke, M.L.; Foster, D.F.; Cole-Hamilton, D.J.; Slawin,
A.M. Z.; Woollins, J.D. J. Chem. Soc. Dalton Trans. 2001, 969–
971.
6. Bhattacharyya, P.; Ly, T.Q.; Slawin, A.M. Z.; Woollins, J.D. Polyhedron
2001, 20, 1803–1808.
7. Guo, R.; Li, X.; Wu, J.; Kwok, W.H.; Chen, J.; Choi, M.C. K.; Chan, A.S.
C. Tetrahedron Lett. 2002, 43, 6803–6806.
¨
¨
8. Gu¨mgu¨m, B.; Akba, O.; Durap, F.; Yıldırım, L.T.; Ulku¨, D.; Ozkar, S.
32. Gopalakrishnan, J. Appl. Organomet. Chem. 2009, 23, 291–318.
33. Pearson, R.G. J. Am. Chem. Soc. 1986, 108, 6109–6114.
Polyhedron 2006, 25, 3133–3137.