Anna Becalska

Photolithography of amorphous films of (η5-C5H5)2Ti(N3)2 on silicon (111) resulting in TiO2: The mechanism of the photodeposition reaction

Photolithography to produce TiO2 patterns from amorphous films of (η5-C5H5)2Ti(N3)2 has been demonstrated. The efficiency of the reaction has been measured yielding a quantum yield of 0.025. The mechanism of the photoreactions of (η5-C5H5)2Ti(N3)2 has been studied using Fourier transform-infrared spectroscopy in both a low-temperature 1,2-epoxyethylbenzene glass and as surface films. In each case the primary photochemical process was found to be loss of a single azido group. The result of subsequent photolysis was found to be dependent upon medium and temperature. In the low-temperature glass no further photochemistry was observed. The exhaustive photolysis of films at 20 K, or room temperature, under a vacuum or in air led to loss of all ligands and the formation of TiO2.

Photochemistry of (η5-C5Me5)Re(CO)2Br2 on Si(III) surfaces at low temperature

Abstract The photolysis of (η5-C5Me5)Re(CO)2Br2 on Si(III) surfaces at 77 K results in cis to trans isomerism. The mechanism of the photoreaction involves CO loss to generate an isomer of (η5-C5Me5)Re(CO)Br2 which, upon warming, reacts thermally with CO to generate only trans-(η5-C5Me5)Re(CO)2Br2. The first isomer of (η5-C5Me5)Re(CO)Br2 is photosensitive and converts to a second isomer which upon reaction with CO yields exclusively cis-(η5-C5Me5)Re(CO)2Br2.

Photochemical reactions of [(η5-C5R5)Mn(CO)2(NO)]+ (R5≡H5, H4Me, Me5) as films and in low temperature glasses

Abstract The photolysis of [(η5-C5R5)Mn(CO)2(NO)]+ (R5  H5, H4Me, Me5) was studied by Fourier transform IR spectroscopy in a low temperature 1,2-epoxyethylbenzene glass and in surface films. In each case the primary photoproduct was found to be [(η5-C5R5)Mn(CO)(NO)]+. The result of subsequent photolysis was observed to be dependent on medium and temperature. In the low temperature glass, NO+ was photoextruded and the resultant organometallic was {(η5-C5R5)Mn(μ-CO)}2. In the film at 77 K, two competing processes were observed: loss of NO and loss of NO+. Unlike the result in the glass, both terminal and bridging CO groups were observed following NO+ loss. Exhaustive photolysis at room temperature in the film led to loss of NO+ and ultimately loss of CO and the cyclopentadienyl ring.

Electron paramagnetic resonance studies of the 19-electron complexes, (η5-C5H5)NiL2 (L = PR3, P(OR)3)

Abstract Photolysis of (η 5 -C 5 H 5 )Ni(R)PPh 3 (R = Me, Et) in air-free benzene leads to the production of the stable radical (η 5 -C 5 H 5 )Ni(PPh 3 ) 2 . In the presence of free ligands, L (L = PPh 3 , P( p -FPh) 3 , P( p -MeOPh) 3 , P( n -Bu) 3 , P(OEt) 3 , P(OPh) 3 , P(OMe) 3 , dppe/2, bipy/2, C 2 Ph 2 and HCCPh), photolysis of (η 5 -C 5 H 5 )Ni(R)PPh 3 leads to the production of (η 5 -C 5 H 5 )Ni(L) 2 . The ESR spectra of several derivatives of the radical, (η 5 -C 5 H 5 )NiL 2 , have been analysed and the variation of the sp hybridization of the phosphorus donor atom determined.

Photochemical reactions of the isostructural 17- and 18-electron complexes (η5-C5H5)M(Me)PPh3 (MCo, Ni)

Abstract The photochemical reactions of the title complexes were studied in air-free benzene solution. In both cases photolysis leads to the production of complexes of the formula (η 5 -C 5 H 5 )M(PPh 3 ) 2 . Both reactions are the result of the initial loss of a methyl radical from the excited state. The primary photoproduct, (η 5 -C 5 H 5 )MPPh 3 (MCO, Ni), then scavenges neutral ligands from the solution to yield, in the case of PPh 3 , (η 5 -C 5 H 5 )M(PPh 3 ) 2 . In the absence of uncoordinated ligand in the reaction solution, the cobalt derivative reacts with the starting material to yield (η 5 -C 5 H 5 )Co(PPh 3 ) 2 , a methyl radical and (η 5 -C 5 H 5 )Co(solvent) n .

Synthesis and characterization of novel 17 electron species of manganese with stable metal–alkyl bonds

The new 17 electron complexes, (η5-C5H4Me)Mn(NO)R2, R = Me, Et, Pr, prepared by alkylation of (η5-C5H4Me)Mn(NO)(PPh3)I, are stable in the absence of oxygen and have been characterized by their 1H n.m.r. and e.s.r. spectra.

The initial reaction of Os3(CO)12 with halogens

The reaction of Os3(CO)12 with chlorine or bromine yields as the first observed product ax,eq-Os3(CO)12(X)2(X = Cl or Br) whereas the corresponding reaction with iodine gives [Os3(CO)12(I)][I3].