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The paper shows the determination of the transmission of one dimensional metal-dielectric photonic band gap materials (1D-MD PBG) theoretically and experimentally. It has been found that the location and bandwidth of transmission can be tailored by initiatively adopting a suitable structure. We proposed a special 1D-MD PBG obtained by magnetron sputtering, in which each layer of metal film is not continuous. These structures have a number of advantages such as high transmittance (55% or better), broad bandwidth (the full width at half of maximum ranges from 400 nm to 780 nm) and high electrical conductivity (the sheet resistance can be lower than 0.98 Ω /square). Meanwhile, it has been also theoretically and experimental indicated that both the light transmittance and electrical conductivity could be improved effectively by using the (pqp)N structure.

Five crystalline 2-(dimethylsila)pyrimidine derivatives ( Z ) have been prepared in excellent 1 – 4 or satisfactory 5 yield and characterised. The source of each was ultimately Li[CH(SiMe 2 R)(SiMe 2 OMe)] [R = Me ( B ) or OMe ( I )]. Compound 1 ( Z with Ar = Ph, X = SiMe 3 , n = 1) was obtained from Z [with Ar = Ph, X = Li(OEt 2 ), n = 4; previously isolated from B [P.B. Hitchcock, M.F. Lappert, X.-H. Wei, J. Organomet. Chem. 689 (2004) 1342]] and Me 3 SiCl. The potassium salt 2 [ Z with Ar = C 6 H 4 Bu t -4; X = K(thf) 3 , n = 2] was made from K[CH(SiMe 3 )(SiMe 2 OMe)] ( C ) (via B ) and 4-Bu t C 6 H 4 CN. Treatment of 2 with 1,2-dibromoethane afforded 3 ( Z with Ar = 4-Bu t C 6 H 4 ; X = H, n = 1); which when reacted with successively n -butyllithium and Me 3 SiCl produced 4 ( Z with Ar = 4-Bu t C 6 H 4 , X = SiMe 3 , n = 1). Compound 5 [ Z with Ar = 4-Bu t C 6 H 4 , X = Li(hmpa) 2 , n = 1] resulted from I with 4-Bu t C 6 H 4 CN and then OP(NMe 2 ) 3 (≡ hmpa). Plausible reaction pathways from the appropriate alkali metal alkyl C or I to 2 or 5 , respectively, are suggested; these involve regiospecific 1,3-migrations of SiMe 2 OMe from C → N and electrocyclic loss of Me 3 SiOMe or SiMe 2 (OMe) 2 , respectively. The X-ray structures of crystalline 1 , 2 and 5 are presented.

Treatment at ambient temperature in diethyl ether of one equivalent of [Li{CH(SiMe3)(SiMe2OMe)}]8 (A) with (i) two equivalents of PhCN, or (ii) successive equivalent portions of ButCN and PhCN gave from (i) (1) and (2) as well as the known lithium 1-azaallyl [Li{N(SiMe2OMe)C(Ph)CH(SiMe3)}]3, and from (ii) (3) The latter was also obtained from the known [Li{N(SiMe2OMe)C(But)CH(SiMe3)}]2 and PhCN under similar conditions. Recrystallisation of 2 from THF/hexane afforded (2′). X-ray diffraction data on 2, 2′ and 3 are presented; data for 1 were only adequate to confirm its gross tetrameric structure. The particularly novel feature of these transformations of the lithium alkyl A into lithium β-diketiminates 1, 2, 2′ or 3 is that while the first 1,3-carbon to nitrogen shift from the α-carbon of A is both silicotropic and regiospecific (in so far as SiMe2OMe > SiMe3 in migratory aptitude), the second migration is indiscriminate: silicotropy yielding 1 or 3 but prototropy giving 2 (or 2′). Consistent with these observations, the central carbon atom of the β-diketiminato ligand has significant carbanionic character in 2 or 2′, attributed to its stabilisation by the exocyclic Me3Si at C2, whereas in 1 or 3 there is π-delocalisation.

Crystalline [Li{N(SiMe2OMe)C(tBu)C(H)(SiMe3)}]2 (5), [Li{N(SiMe2OMe)C(Ph)C(H)(SiMe3)}]2 (6), [ Li{N(SiMe 2 OMe)C(C 6 H 3 Me 2 -2,5)N C(C6H3Me2-2,5)C(H)(SiMe3)}(TMEDA)](7), [Li{N(SiMe(OMe)2)C(tBu)C(H)(SiMe3)}(THF)]2 (8), Li{N(SiMe(OMe)2)C(Ph)C(H)(SiMe3)}(TMEDA) (9) and [Li{N(SiMe2OMe)C(tBu)C(H)(SiMe2OMe)}]2 (10) were readily obtained at ambient temperature from (i) [Li{CH(SiMe3)(SiMe2OMe)}]8 (1) and an equivalent portion of RCN (R=tBu (5), Ph (6) or 2,5-Me2C6H3 (7)); (ii) [Li{CH(SiMe3)(SiMe(OMe)2)}]∞ (2) and an equivalent portion of tBuCN (8) or PhCN (9); and (iii) [Li{CH(SiMe2OMe)2}]∞ (3) and one equivalent of tBuCN (10). Reactions (i) and (ii) were regiospecific with SiMe3−n(OMe)n>SiMe3 in 1,3-migration from C (in 1 or 2)→N. The 1-azaallyl ligand was bound to the lithium atom as a terminally bound κ1-enamide (8 and 10), a bridging η3-1-azaallyl (6), or a bridging κ1-enamide (5). The stereochemistry about the CC bond was Z for 5, 8 and 10 and E for 7. X-ray data are provided for 5, 6, 7, 8 and 10 and multinuclear NMR spectra data in C6D6 or C6D5CD3 for each of 5–10.

Reactions of bis(trimethylsilyl)methyl lithium reagent Li[CHR2] (R=SiMe3) and 1-azaallyllithium, [ LiN(R)C(Bu t )C HR]2 with cyanoamines R′CN (R′=Me2N, 1-piperidyl or o, p-pyridyl) yielded β-diketiminatolithiums (1, 2, 5, 7, 8) or symmetrically and mixed substituted triazines (3, 4, 6, 9, 10), respectively. The mechanistic pathways involve silicotropic rearrangements from C to N or N to N and an unusual elimination of Li[CHR2]. The complexes 1, 6, 7, and 10 had been characterized by X-Ray diffraction.