The 6π, phosphide-stabilised stannylene dianion [C6H4P2Sn]2−; the first member of a new class of Arduengo-type carbene analogues

Abstract

Dilithiation of 1,2-(PH2)2C6H4 with nBuLi followed by reaction with Sn(NMe2)2 in the presence of the Lewis base donor tmeda [Me2NCH2CH2NMe2] gives [(C6H4P2Sn)(Li.tmeda)2] , containing the phosphide-stabilised, 6pi stannylene dianion [C6H4P2Sn]2-.

Structure and Bonding in Stannadiphospholes and their Dianions SnC2P2R2m (R=H, tBu m=0, −2): A Comparative Study with C5H5+ and C5H5− Analogues

“…[6] The p-electron delocalisation is severely affected by the large differences in the energies of the p orbitals from C, P and Sn involved in the p bonding. One major consequence of this can be anticipated in the ligating properties of these rings: the recently reported structure for the dilithio salt of the C 6 H 4 P 2 Sn 2À di-A C H T U N G T R E N N U N G anion, [8] for example, has a different h…”

“…[6][7][8][9][10][11] They also can exhibit enhanced p-acceptor properties, such as in the cases of 1,2,4-or 1,2,3-triphospholide anions [4,6,7] and the 1,2,3-triphosphaindenyl anion C 6 H 4 P 3 À . The last of these is prepared by the simple procedure of deprotonation of 1,2-diphosphinobenzene with nBuLi followed by treatment with PCl 3 [6] or SbA C H T U N G T R E N N U N G (NMe 2 ) 3 [7] in the presence of [Li[12]crown-4) 2 ]…”

“…Other isoelectronic analogues are prepared by deprotonation of 1,2-(YH 2 ) 2 C 6 H 4 (Y = N, P) with nBuLi/EA C H T U N G T R E N N U N G (NMe 2 ) m (E = Sn, Sb and m = 2, 3) in the presence of N,N,N',N'-tetramethylethylenediamine (TMEDA) as the solvent. [8] This procedure also affords sideproducts, such as Hittorfs phosphorus [6] or Zintl-type [9] ions [Sb 7 {Li 3 ·6 NHMe 2 }]. [2] The diphosphoindenyl ions are also isoelectronic with dithiazolyl radicals [10] and triazolyl anions, [11] which have been extensively used in magnetic storage devices and in coordination chemistry, respectively.…”

“…In the case of Sn, the p donation into the vacant orbital of the two-coordinate Sn II centre makes it a substantial new class of Arduengo-type carbenes. [8] Interestingly, the first reported metal 1,3-diphosphadicyclobutadiene complex [Sn h 4 -(tBu 2 C 2 P 2 )], which involves a Sn II centre [12] is a 24 e À five-vertex nido cluster possessing six interstitial p electrons according to ring-capping criteria. [13] Its Mçssbauer spectrum and 119 Sn NMR chemical shift are consistent with a tin(II) complex, [12b, c] whereas the photoelectron spectrum coupled with DFT calculations indicate that the tin binds to the diphosphacyclobutadiene through interactions between the three lowest-energy p orbitals of the ring and three valence orbitals of the metal.…”

Utilising hydraulic transient excitation for fatigue crack monitoring of a cast iron pipeline using optical distributed sensing

“…Recent advancements of the technology allows DOFS to perform continuous and in situ monitoring of pipeline integrity. The distributed optical sensing has been implemented to monitor the pipe response due to ground movement, [3] leak detection, [4] and pipe buckling. [5] Vectorial dislocations of pipes induced by bending can also be detected using three DOFS installed 120°apart along the axial length of the pipes.…”