Victor Christou - Academia.edu (original) (raw)
Papers by Victor Christou
Proceedings of SPIE, Jun 25, 2002
The periodic helical structure of an aligned cholesteric liquid crystal gives rise to circular Br... more The periodic helical structure of an aligned cholesteric liquid crystal gives rise to circular Bragg reflection such that circularly polarised light of the same handedness as the helix is reflected while counter circularly polarised light is transmitted. The resulting circularly polarised 1D photonic band gap can be used to suppress or enhance circularly polarised photoluminescence from a fluorescent guest material embedded in a chiral host whose resonance region coincides with the emission of the fluorophor. The periodic structure of the host suppresses emission of one circular handedness of certain frequencies and enhances the suppressed emission at the edges of the reflection band. To avoid the effects of redistributing the photon density of states across the spontaneous emission spectrum and to observe inhibition of spontaneous emission of one handedness a very narrow fluorophor is needed. In this paper, an organoterbium complex is embedded in a cholesteric reactive mesogen (RM) host, which is subsequently polymerized by UV-exposure to generate a chiral polymer. The reflection band of the chiral host is tuned to completely overlap the different emission lines of the organolanthanide as well as to lie in between them. We investigate how the suppression of one emission channel causes a redistribution of probabilities for the remaining pathways resulting in a spectral and spatial redistribution of emission.
The Journal of Physical Chemistry A, 2002
The excitation energy transfer rates between the excited states of a Tb(III) complex containing t... more The excitation energy transfer rates between the excited states of a Tb(III) complex containing the ligand 1-phenyl-3-methyl-4-(trimethylacetyl)pyrazol-4-one, are described. Energy transfer rate constants are derived from time-gated and time-correlated single photon counting measurements. Comparison with the analogous Gd(III) complex shows that there is efficient intramolecular energy transfer from a singlet state of the ligand to excited terbium f-electron states. There is no evidence of bi-exciton annihilation in these materials, even at very high exciton densities. The use of this complex as the active medium for electroluminescent device applications is addressed. We note the particular properties of the ligand which make it suitable for this application and suggest possible improvements.
Journal of the Chemical Society, Dalton Transactions, 1998
... 26, DR Cary, GE Ball and J. Arnold, J. Am. ... 34, GAUSSIAN 94 (Revision A.1), MJ Frisch, GW ... more ... 26, DR Cary, GE Ball and J. Arnold, J. Am. ... 34, GAUSSIAN 94 (Revision A.1), MJ Frisch, GW Trucks, HB Schlegel, PMW Gill, BG Johnson, MA Robb, JR Cheeseman, TA Keith, GA Petersson, JA Montgomery, K. Ragavachari, MA Al-Laham, VG Zakrewski, JV Ortiz, JB Foresman, J ...
SID Symposium Digest of Technical Papers, 1999
Organic EL devices with excellent red CIE colour coordinates, based upon the new lanthanide EL ma... more Organic EL devices with excellent red CIE colour coordinates, based upon the new lanthanide EL material Eu[Ph2P(O)NP(O)Ph2]3(Eupip3) are described. Several device structures are reported and the effects of charge transport layers on device structure critically assessed. Improved device performance from an unencapsulated device using an aluminum cathode is achieved in a three layer structure with TPD and TAZ as the charge transport layers. This device has an efficiency of 0.02 % at 20 cd/m2 at 25 V and 1 mA/cm2.
SPIE Proceedings, 2002
The periodic helical structure of an aligned cholesteric liquid crystal gives rise to circular Br... more The periodic helical structure of an aligned cholesteric liquid crystal gives rise to circular Bragg reflection such that circularly polarised light of the same handedness as the helix is reflected while counter circularly polarised light is transmitted. The resulting circularly ...
Thin Solid Films, 2000
In this paper, a vacuum-deposited multilayer cathode for organic light-emitting diodes OLEDs with... more In this paper, a vacuum-deposited multilayer cathode for organic light-emitting diodes OLEDs with reduced reflectivity is Ž 3 3. Ž. butylphenyl-1,2,4-triazole TAZ , the injection properties of such a multilayer cathode are presented and compared to those of AlrMg and CrAl cathodes. Such a cathode shows promise for contrast improvements in OLEDs.
Synthetic Metals, 2001
Single layer devices of the organolanthanide complex, terbium Tris-(1-phenyl-3-methyl-4-(tertiary... more Single layer devices of the organolanthanide complex, terbium Tris-(1-phenyl-3-methyl-4-(tertiarybutyryl)pyrazol-5-one)triphenylphosphine oxide [(tb-PMP) 3 Tb(Ph 3 PO)] were made to investigate its light emission and current transporting properties. Ca and Mg layers were used for the cathode contact. A higher current density at much lower voltages can be attained with Ca cathode because of the enhanced electron injection. The maximum brightness of a single layer device with a Ca cathode was 226 cd/m 2 at 18 V and the best electroluminescence (EL) ef®ciency was 0.67 cd/A at 14 V and 70 cd/m 2 .
Synthetic Metals, 2000
Ž. w Ž. Ž. x Ž. Organic electroluminescent EL devices based upon the new lanthanide EL material T... more Ž. w Ž. Ž. x Ž. Organic electroluminescent EL devices based upon the new lanthanide EL material Tb Ph P O NP O Ph Tbpip are described. 2 2 3 3 Several device structures are reported and the effect of charge transporting material and layer thickness on device performance critically assessed. Device performance is optimised in a three-layer structure containing TPD and Alq as the charge transport layers. This device has an efficiency of 0.7 cd A y1 at 20 cd m y2 at 25 V and 1 mA cm y2 .
Synthetic Metals, 2002
Devices containing the europium complex Eu(TTFA) 3 (phen) were fabricated by spin-coating. The co... more Devices containing the europium complex Eu(TTFA) 3 (phen) were fabricated by spin-coating. The complex was doped into poly(9vinylcarbazole) (PVK) along with (4-tert-butylphenyl)biphenyloxadiazole (PBD) as electron-transporting material. Addition of an evaporated layer of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (bathocuproine, BCP) forming a two-layer device structure between indium-tin oxide (ITO) and Ca:Al electrodes gave enhanced brightness and ef®ciency. A device 3 wt.% Eu(TTFA) 3 (phen):32 wt.% PBD:PVK with a BCP hole-blocking layer gave Eu emission with a maximum luminance of 417 cd m À2 at 25 V and 175 mA cm À2 .
Journal of the American Chemical Society, 1992
The latter measurements were performed on thin films heat-treated under conditions identical to 3... more The latter measurements were performed on thin films heat-treated under conditions identical to 3, except for the ionomer-intercalated MOO, which was heated at 50 O C. (19) XPS measurements on thin films of 2, 3, and Na,MoO, all showed an O/Mo ratio of close to 3, and Mol,, high-resolution spectra showed no significant difference in the Mo(V)/Mo(VI) ratio. If deoxygenation was responsible for the increased conductivity, we would also have expected it to occur in monomer-intercalated MOO,.
Journal of the American Chemical Society, 1993
The preparation of a series of chalcogenolate species (sol),LiEY(SiMe3)3 (sol = THF, n = 1,2; sol... more The preparation of a series of chalcogenolate species (sol),LiEY(SiMe3)3 (sol = THF, n = 1,2; sol = DME, n = 1; E = S, Se, Te; Y = C, Si, Ge) by direct insertion of elemental E into Li-Y bonds of (THF),LiC(SiMe,),, (THF),LiSi(SiMe&, or (THF),LiGe(SiMe& is reported. Two derivatives, (THF)zLiSeSi(SiMe& and (THF)-LiSSi(SiMe3),, are more conveniently prepared by novel chalcogen metathesis reactions whereby tellurium is displaced from (THF)zLiTeSi(SiMe& by either Se or S in THF at-55 OC. Protonation of the chalcogenolate anions leads to the stable chalcogenols, HEY(SiMe3)3, which have been fully characterized. In methyl isobutyl ketone (MIBK), the pKa values of HTeC(SiMe&, HTeSi(SiMe3)3, HTeGe(SiMe&, HSeC(SiMe&, HSeSi(SiMe&, and HSSi(SiMes), are determined to be 9.3, 7.3, 7.4, 10.8, 8.3, and 10.7, respectively. The X-ray structure of the mono-THF adduct (THF)LiTeSi(SiMe&, prepared from (THF)Li[N(SiMe&] and HTeSi(SiMe&, is also described; it crystallizes in the triclinic space group Pi with a = 9.083(4) A, b = 11.181(4) A, c = 12.053(8) A, a = 93.16(4)O, 0 = 104.68(5)O,
Journal of the American Chemical Society, 1993
... Victor Christou, Stephen P. Wuller, and John Arnold' ... Addition of only 1 equiv of tel... more ... Victor Christou, Stephen P. Wuller, and John Arnold' ... Addition of only 1 equiv of tellurol at 20 OC results in protonation of a single Zr-Me bond and formation of the orange-red methyl (17) For examples of typical CpzTiL2 type structures see: (a) Davis, B. R.; Bernal, I. J . Organome ...
Journal of Applied Physics, 2000
... V. Christou, M. Etchells, O. Renault, PJ Dobson, OV Salata, G. Beamson, RG Egdell. ... Plasma... more ... V. Christou, M. Etchells, O. Renault, PJ Dobson, OV Salata, G. Beamson, RG Egdell. ... Plasma oxidation or chemical oxidation also reduces the level of carbon contamination on ITO surfaces (Table ), but as will emerge in the discussion below we believe that the removal of ...
Inorganica Chimica Acta, 2010
Treatment of the ligands 3,5-tBu2-2-(OH)C6H2CHNR [R=2-(CO2H)C6H4 (1a) and 2-(CO2H)C10H6 (1b)] wit... more Treatment of the ligands 3,5-tBu2-2-(OH)C6H2CHNR [R=2-(CO2H)C6H4 (1a) and 2-(CO2H)C10H6 (1b)] with trimethylborate, B(OMe)3, in toluene yields, after work-up, the yellow crystalline complexes {[3,5-tBu2-2-(O)C6H2CHNR]B(OMe)} [R=2-(CO2)C6H4 (2a) and 2-(CO2)C10H6 (2b)], respectively. Further treatment of these complexes with trifluoromethanesulfonic (triflic) acid, CF3SO3H, followed by recrystallisation from tetrahydrofuran (thf) afforded the triflate salts [{3,5-tBu2-2-(O)C6H2CHNR}B(thf)][CF3SO3] [R=2-(CO2)C6H4 (3a) and 2-(CO2)C10H6 (3b)]. An electroluminescent device was constructed using 2a, which produced orange-green light with broad emission spectra (maximum brightness of 5cd/m2 being observed at 13V). Compounds 1a and 2b·2MeCN have been characterised by single crystal X-ray structure determinations.
Inorganic Chemistry, 1996
ABSTRACT A combination of either salt metathesis reactions between MCl4 (M = Zr, Hf) and (THF)2Li... more ABSTRACT A combination of either salt metathesis reactions between MCl4 (M = Zr, Hf) and (THF)2LiSeSi(SiMe3)3 (THF = tetrahydrofuran) or between TiCl3(THF)3 and (THF)2LiESi(SiME3)3 (E = Se, Te), or chalcogenolysis reactions between M(CH2Ph)4 (M = Zr, Hf) and HESi(SiMe3)3 (E = Se, Te) afforded the series of compounds M[ESi(SiMe3)3]4 (M = Ti, Zr, Hf; E = Se, Te). The X-ray structures of M[TeSi(SiMe3)3]4 (M = Zr, Hf) and Zr[SeSi(SiMe3)3]4 have been determined and are presented for comparison. Reaction of group 4 tetrabenzyls with 3 equiv of HSeSi(SiMe3)3 gave the complexes M[SeSi(SiMe3)3]3(CH2Ph) (M = Ti, Zr, Hf) in high yields. Treatment of the zirconium and hafnium homoleptic tellurolates with 2 equiv of xylyl isocyanide produced the bis-L trans adducts M[TeSi(SiMe3)3]4[CN(xylyl)]2 (M = Zr, Hf) in moderate yields. The related six-coordinate DMPE adducts M[TeSi(SiMe3)3]4(DMPE) (M = Zr, Hf; DMPE = 1,2-bis(dimethylphosphino)ethane) were similarly prepared. Reaction of the mono-DMPE complexes with a second equilvalent of DMPE led to the elimination of Te[Si(SiMe3)3]2 and the formation of the seven-coordinate bis(tellurolate), bis(DMPE), terminal tellurides M[TeSi(SiMe3)3]2(Te)(DMPE)2 (M = Zr, Hf). Both of the tellurides have been structurally characterized. The homoleptic zirconium selenolate reacts with 1 equiv of DMPE, yielding a bright red material with the stoichiometry Zr[SeSi(SiMe3)3]2(Se)(DMPE). The diphosphine DMPM (DMPM = 1,2-bis(dimethylphosphino)methane) also reacted with M[SeSi(SiMe3)3]4 (M = Zr, Hf) to give the bis(μ-Se), A-frame dimers {M[SeSi(SiMe3)3]2(μ-Se)(μ-η2-DMPM)}2 (M = Zr, Hf) in relatively low yields (40 and 23%). The structure of the zirconium derivative has been confirmed using X-ray crystallography. Crystallographic data are as follows: Zr[SeSi(SiMe3)3]4, monoclinic, P21/c, a = 22.6944(34) Å, b = 15.2943(55) Å, c = 22.7758(61) Å, β = 105.695(17)°, Z = 4, R = 5.29, Rw = 3.69; Hf[TeSi(SiMe3)3]4, monoclinic, P21/c, a = 22.494(5) Å, b = 15.609(5) Å, c = 22.742(5) Å, β = 104.480(5)°, Z = 4, R = 4.48, Rw = 5.45; Hf[TeSi(SiMe3)3]2(Te)(DMPE)2, monoclinic, P21, a = 14.795(3) Å, b = 14.289(3) Å, c = 15.4212(2) Å, β = 102.543(3)°, Z = 2, R = 4.78, Rw = 6.70; {Zr[SeSi(SiMe3)3]2(μ-Se)(μ-η2-DMPM)}2, monoclinic, P21/n, a = 14.7651(13) Å, b = 18.8579(17) Å, c = 18.6072(17) Å, β = 111.031(1)°, Z = 2, R = 8.26, Rw = 8.13.
Proceedings of SPIE, Jun 25, 2002
The periodic helical structure of an aligned cholesteric liquid crystal gives rise to circular Br... more The periodic helical structure of an aligned cholesteric liquid crystal gives rise to circular Bragg reflection such that circularly polarised light of the same handedness as the helix is reflected while counter circularly polarised light is transmitted. The resulting circularly polarised 1D photonic band gap can be used to suppress or enhance circularly polarised photoluminescence from a fluorescent guest material embedded in a chiral host whose resonance region coincides with the emission of the fluorophor. The periodic structure of the host suppresses emission of one circular handedness of certain frequencies and enhances the suppressed emission at the edges of the reflection band. To avoid the effects of redistributing the photon density of states across the spontaneous emission spectrum and to observe inhibition of spontaneous emission of one handedness a very narrow fluorophor is needed. In this paper, an organoterbium complex is embedded in a cholesteric reactive mesogen (RM) host, which is subsequently polymerized by UV-exposure to generate a chiral polymer. The reflection band of the chiral host is tuned to completely overlap the different emission lines of the organolanthanide as well as to lie in between them. We investigate how the suppression of one emission channel causes a redistribution of probabilities for the remaining pathways resulting in a spectral and spatial redistribution of emission.
The Journal of Physical Chemistry A, 2002
The excitation energy transfer rates between the excited states of a Tb(III) complex containing t... more The excitation energy transfer rates between the excited states of a Tb(III) complex containing the ligand 1-phenyl-3-methyl-4-(trimethylacetyl)pyrazol-4-one, are described. Energy transfer rate constants are derived from time-gated and time-correlated single photon counting measurements. Comparison with the analogous Gd(III) complex shows that there is efficient intramolecular energy transfer from a singlet state of the ligand to excited terbium f-electron states. There is no evidence of bi-exciton annihilation in these materials, even at very high exciton densities. The use of this complex as the active medium for electroluminescent device applications is addressed. We note the particular properties of the ligand which make it suitable for this application and suggest possible improvements.
Journal of the Chemical Society, Dalton Transactions, 1998
... 26, DR Cary, GE Ball and J. Arnold, J. Am. ... 34, GAUSSIAN 94 (Revision A.1), MJ Frisch, GW ... more ... 26, DR Cary, GE Ball and J. Arnold, J. Am. ... 34, GAUSSIAN 94 (Revision A.1), MJ Frisch, GW Trucks, HB Schlegel, PMW Gill, BG Johnson, MA Robb, JR Cheeseman, TA Keith, GA Petersson, JA Montgomery, K. Ragavachari, MA Al-Laham, VG Zakrewski, JV Ortiz, JB Foresman, J ...
SID Symposium Digest of Technical Papers, 1999
Organic EL devices with excellent red CIE colour coordinates, based upon the new lanthanide EL ma... more Organic EL devices with excellent red CIE colour coordinates, based upon the new lanthanide EL material Eu[Ph2P(O)NP(O)Ph2]3(Eupip3) are described. Several device structures are reported and the effects of charge transport layers on device structure critically assessed. Improved device performance from an unencapsulated device using an aluminum cathode is achieved in a three layer structure with TPD and TAZ as the charge transport layers. This device has an efficiency of 0.02 % at 20 cd/m2 at 25 V and 1 mA/cm2.
SPIE Proceedings, 2002
The periodic helical structure of an aligned cholesteric liquid crystal gives rise to circular Br... more The periodic helical structure of an aligned cholesteric liquid crystal gives rise to circular Bragg reflection such that circularly polarised light of the same handedness as the helix is reflected while counter circularly polarised light is transmitted. The resulting circularly ...
Thin Solid Films, 2000
In this paper, a vacuum-deposited multilayer cathode for organic light-emitting diodes OLEDs with... more In this paper, a vacuum-deposited multilayer cathode for organic light-emitting diodes OLEDs with reduced reflectivity is Ž 3 3. Ž. butylphenyl-1,2,4-triazole TAZ , the injection properties of such a multilayer cathode are presented and compared to those of AlrMg and CrAl cathodes. Such a cathode shows promise for contrast improvements in OLEDs.
Synthetic Metals, 2001
Single layer devices of the organolanthanide complex, terbium Tris-(1-phenyl-3-methyl-4-(tertiary... more Single layer devices of the organolanthanide complex, terbium Tris-(1-phenyl-3-methyl-4-(tertiarybutyryl)pyrazol-5-one)triphenylphosphine oxide [(tb-PMP) 3 Tb(Ph 3 PO)] were made to investigate its light emission and current transporting properties. Ca and Mg layers were used for the cathode contact. A higher current density at much lower voltages can be attained with Ca cathode because of the enhanced electron injection. The maximum brightness of a single layer device with a Ca cathode was 226 cd/m 2 at 18 V and the best electroluminescence (EL) ef®ciency was 0.67 cd/A at 14 V and 70 cd/m 2 .
Synthetic Metals, 2000
Ž. w Ž. Ž. x Ž. Organic electroluminescent EL devices based upon the new lanthanide EL material T... more Ž. w Ž. Ž. x Ž. Organic electroluminescent EL devices based upon the new lanthanide EL material Tb Ph P O NP O Ph Tbpip are described. 2 2 3 3 Several device structures are reported and the effect of charge transporting material and layer thickness on device performance critically assessed. Device performance is optimised in a three-layer structure containing TPD and Alq as the charge transport layers. This device has an efficiency of 0.7 cd A y1 at 20 cd m y2 at 25 V and 1 mA cm y2 .
Synthetic Metals, 2002
Devices containing the europium complex Eu(TTFA) 3 (phen) were fabricated by spin-coating. The co... more Devices containing the europium complex Eu(TTFA) 3 (phen) were fabricated by spin-coating. The complex was doped into poly(9vinylcarbazole) (PVK) along with (4-tert-butylphenyl)biphenyloxadiazole (PBD) as electron-transporting material. Addition of an evaporated layer of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (bathocuproine, BCP) forming a two-layer device structure between indium-tin oxide (ITO) and Ca:Al electrodes gave enhanced brightness and ef®ciency. A device 3 wt.% Eu(TTFA) 3 (phen):32 wt.% PBD:PVK with a BCP hole-blocking layer gave Eu emission with a maximum luminance of 417 cd m À2 at 25 V and 175 mA cm À2 .
Journal of the American Chemical Society, 1992
The latter measurements were performed on thin films heat-treated under conditions identical to 3... more The latter measurements were performed on thin films heat-treated under conditions identical to 3, except for the ionomer-intercalated MOO, which was heated at 50 O C. (19) XPS measurements on thin films of 2, 3, and Na,MoO, all showed an O/Mo ratio of close to 3, and Mol,, high-resolution spectra showed no significant difference in the Mo(V)/Mo(VI) ratio. If deoxygenation was responsible for the increased conductivity, we would also have expected it to occur in monomer-intercalated MOO,.
Journal of the American Chemical Society, 1993
The preparation of a series of chalcogenolate species (sol),LiEY(SiMe3)3 (sol = THF, n = 1,2; sol... more The preparation of a series of chalcogenolate species (sol),LiEY(SiMe3)3 (sol = THF, n = 1,2; sol = DME, n = 1; E = S, Se, Te; Y = C, Si, Ge) by direct insertion of elemental E into Li-Y bonds of (THF),LiC(SiMe,),, (THF),LiSi(SiMe&, or (THF),LiGe(SiMe& is reported. Two derivatives, (THF)zLiSeSi(SiMe& and (THF)-LiSSi(SiMe3),, are more conveniently prepared by novel chalcogen metathesis reactions whereby tellurium is displaced from (THF)zLiTeSi(SiMe& by either Se or S in THF at-55 OC. Protonation of the chalcogenolate anions leads to the stable chalcogenols, HEY(SiMe3)3, which have been fully characterized. In methyl isobutyl ketone (MIBK), the pKa values of HTeC(SiMe&, HTeSi(SiMe3)3, HTeGe(SiMe&, HSeC(SiMe&, HSeSi(SiMe&, and HSSi(SiMes), are determined to be 9.3, 7.3, 7.4, 10.8, 8.3, and 10.7, respectively. The X-ray structure of the mono-THF adduct (THF)LiTeSi(SiMe&, prepared from (THF)Li[N(SiMe&] and HTeSi(SiMe&, is also described; it crystallizes in the triclinic space group Pi with a = 9.083(4) A, b = 11.181(4) A, c = 12.053(8) A, a = 93.16(4)O, 0 = 104.68(5)O,
Journal of the American Chemical Society, 1993
... Victor Christou, Stephen P. Wuller, and John Arnold' ... Addition of only 1 equiv of tel... more ... Victor Christou, Stephen P. Wuller, and John Arnold' ... Addition of only 1 equiv of tellurol at 20 OC results in protonation of a single Zr-Me bond and formation of the orange-red methyl (17) For examples of typical CpzTiL2 type structures see: (a) Davis, B. R.; Bernal, I. J . Organome ...
Journal of Applied Physics, 2000
... V. Christou, M. Etchells, O. Renault, PJ Dobson, OV Salata, G. Beamson, RG Egdell. ... Plasma... more ... V. Christou, M. Etchells, O. Renault, PJ Dobson, OV Salata, G. Beamson, RG Egdell. ... Plasma oxidation or chemical oxidation also reduces the level of carbon contamination on ITO surfaces (Table ), but as will emerge in the discussion below we believe that the removal of ...
Inorganica Chimica Acta, 2010
Treatment of the ligands 3,5-tBu2-2-(OH)C6H2CHNR [R=2-(CO2H)C6H4 (1a) and 2-(CO2H)C10H6 (1b)] wit... more Treatment of the ligands 3,5-tBu2-2-(OH)C6H2CHNR [R=2-(CO2H)C6H4 (1a) and 2-(CO2H)C10H6 (1b)] with trimethylborate, B(OMe)3, in toluene yields, after work-up, the yellow crystalline complexes {[3,5-tBu2-2-(O)C6H2CHNR]B(OMe)} [R=2-(CO2)C6H4 (2a) and 2-(CO2)C10H6 (2b)], respectively. Further treatment of these complexes with trifluoromethanesulfonic (triflic) acid, CF3SO3H, followed by recrystallisation from tetrahydrofuran (thf) afforded the triflate salts [{3,5-tBu2-2-(O)C6H2CHNR}B(thf)][CF3SO3] [R=2-(CO2)C6H4 (3a) and 2-(CO2)C10H6 (3b)]. An electroluminescent device was constructed using 2a, which produced orange-green light with broad emission spectra (maximum brightness of 5cd/m2 being observed at 13V). Compounds 1a and 2b·2MeCN have been characterised by single crystal X-ray structure determinations.
Inorganic Chemistry, 1996
ABSTRACT A combination of either salt metathesis reactions between MCl4 (M = Zr, Hf) and (THF)2Li... more ABSTRACT A combination of either salt metathesis reactions between MCl4 (M = Zr, Hf) and (THF)2LiSeSi(SiMe3)3 (THF = tetrahydrofuran) or between TiCl3(THF)3 and (THF)2LiESi(SiME3)3 (E = Se, Te), or chalcogenolysis reactions between M(CH2Ph)4 (M = Zr, Hf) and HESi(SiMe3)3 (E = Se, Te) afforded the series of compounds M[ESi(SiMe3)3]4 (M = Ti, Zr, Hf; E = Se, Te). The X-ray structures of M[TeSi(SiMe3)3]4 (M = Zr, Hf) and Zr[SeSi(SiMe3)3]4 have been determined and are presented for comparison. Reaction of group 4 tetrabenzyls with 3 equiv of HSeSi(SiMe3)3 gave the complexes M[SeSi(SiMe3)3]3(CH2Ph) (M = Ti, Zr, Hf) in high yields. Treatment of the zirconium and hafnium homoleptic tellurolates with 2 equiv of xylyl isocyanide produced the bis-L trans adducts M[TeSi(SiMe3)3]4[CN(xylyl)]2 (M = Zr, Hf) in moderate yields. The related six-coordinate DMPE adducts M[TeSi(SiMe3)3]4(DMPE) (M = Zr, Hf; DMPE = 1,2-bis(dimethylphosphino)ethane) were similarly prepared. Reaction of the mono-DMPE complexes with a second equilvalent of DMPE led to the elimination of Te[Si(SiMe3)3]2 and the formation of the seven-coordinate bis(tellurolate), bis(DMPE), terminal tellurides M[TeSi(SiMe3)3]2(Te)(DMPE)2 (M = Zr, Hf). Both of the tellurides have been structurally characterized. The homoleptic zirconium selenolate reacts with 1 equiv of DMPE, yielding a bright red material with the stoichiometry Zr[SeSi(SiMe3)3]2(Se)(DMPE). The diphosphine DMPM (DMPM = 1,2-bis(dimethylphosphino)methane) also reacted with M[SeSi(SiMe3)3]4 (M = Zr, Hf) to give the bis(μ-Se), A-frame dimers {M[SeSi(SiMe3)3]2(μ-Se)(μ-η2-DMPM)}2 (M = Zr, Hf) in relatively low yields (40 and 23%). The structure of the zirconium derivative has been confirmed using X-ray crystallography. Crystallographic data are as follows: Zr[SeSi(SiMe3)3]4, monoclinic, P21/c, a = 22.6944(34) Å, b = 15.2943(55) Å, c = 22.7758(61) Å, β = 105.695(17)°, Z = 4, R = 5.29, Rw = 3.69; Hf[TeSi(SiMe3)3]4, monoclinic, P21/c, a = 22.494(5) Å, b = 15.609(5) Å, c = 22.742(5) Å, β = 104.480(5)°, Z = 4, R = 4.48, Rw = 5.45; Hf[TeSi(SiMe3)3]2(Te)(DMPE)2, monoclinic, P21, a = 14.795(3) Å, b = 14.289(3) Å, c = 15.4212(2) Å, β = 102.543(3)°, Z = 2, R = 4.78, Rw = 6.70; {Zr[SeSi(SiMe3)3]2(μ-Se)(μ-η2-DMPM)}2, monoclinic, P21/n, a = 14.7651(13) Å, b = 18.8579(17) Å, c = 18.6072(17) Å, β = 111.031(1)°, Z = 2, R = 8.26, Rw = 8.13.