Christopher N. Harmer

Sterically induced cis isomerism in an Sb(III) imido dimer; synthesis, structure and solution dynamics of [(Me2N)Sb(μ-NDipp)]2 (Dipp = 2,6-Pr2iC6H3)

Abstract The reaction of [Sb(NMe2)3] with the sterically bulky amine [DippNH2] gives the unusual cis dimer [(Me2N)Sb(μ-NDipp)]2 1, containing a puckered Sb2N2 core. 1H NMR studies show that the cis conformation is retained in solution.

Loosely bonded adducts of plumbocene; structures and solution dynamics of [(η-C5H5)2Pb·tmeda] and [(η-C5H5)2Pb·4,4′-Me2bipy](tmeda = Me2NCH2CH2NMe2, 4,4′-Me2bipy = 4,4′-dimethylbipyridine)

The first Lewis-base adducts of a neutral p-block group metallocene, [(η-C5H5)2Pb·tmeda] 1 and [η-C5H5)2Pb·4,4′-Me2bipy] 2, result from the addition of tmeda and 4,4′-Me2bipy to [Pb(η-C5H5)2](1:1 equiv.); X-ray and solution studies reveal that the Lewis bases are only loosely associated to the PbII centres in these complexes.

Synthesis and structure of [Sb{(Pr i N) 2 CNHPr i }{(Pr i N) 2 CNPr i }]; a distorted trigonal-bipyramidal antimony(iii) complex with a helical hydrogen-bond network

1,2,3-Triisopropylguanidine [(Pr i NH) 2 CNPr i ], reacts with antimony tris(dimethylamide) [Sb(NMe 2 ) 3 ] to provide [Sb{(Pr i N) 2 CNHPr i }{(Pr i N) 2 CNPr i }] 1, a heavily distorted trigonal-bipyramidal complex in which the Sb is chelated by a [C(NPr i ) 3 ] 2- dianion and a [(Pr i N) 2 CNHPr i ] - monoanion; in the solid state the complexes form helices by N–H···N hydrogen bonding of the single proton.

Nucleophilic substitution vs. acid–base reactions of[Mn{N(SiMe3)2}2]·2thf;syntheses and structures of2[Li(thf)4]+[Mn(C12H8N)4]2-·C6H5Me and[Mn(C12H8N)2]·3thf(thf = tetrahydrofuran,C12H8N = carbazol-9-yl)

The ion-separated complex 2[Li(thf) 4 ] + [Mn(C 12 H 8 N) 4 ] 2- 1 has been obtained from the nucleophilic substitution reaction of [Mn{N(SiMe 3 ) 2 } 2 ]·2thf with Li[C 12 H 8 N] (1∶4 equivalents) (thf = tetrahydrofuran, C 12 H 8 N = carbazol-9-yl), and the molecular species [Mn(C 12 H 8 N) 2 ]·3thf 2 from the acid–base reaction of [Mn{N(SiMe 3 ) 2 } 2 ]·2thf and C 12 H 8 NH (1∶2 equivalents). They are among the few amidomanganese(II) complexes containing simple (sterically undemanding) dialkyl- or diaryl-amido groups to be characterised. The crystal structures of both were determined: 1 contains the first tetraamidomanganese(II) dianion and 2 possesses the highest co-ordination number for Mn II in such a compound.

STRUCTURED ASSEMBLY OF HETEROMETALLIC ARRAYS

A range of heterometallic cage complexes can be prepared by step-wise metallation reactions of monolithiated primary amines and phosphines ([REHLi]n; E= N, P) with various Group 13, 14 and 15 metal reagents. The p block imido and phosphinidine anions present in these species are novel ligand systems to main group and transition metals. This simple synthetic approach thereby provides a basis for structured assembly of a range of heterometallic cage and ring compounds.

Metal selection of ligand functionality in[(mes)2P(O)2Li·2thf]2 and[{(Me3Si)2N}Cd{(mes)2PO}2Li·2thf] (mes =C6H2Me3-2,4,6)

The reaction of LiBu n with [(mes) 2 P(H)O] affords the diorganophosphinate complex [(mes) 2 P(O) 2 Li·2thf] 1 and [(mes) 2 PLi], however, addition of [Cd{N(SiMe 3 ) 2 } 2 ] to the mixture gives the diorganophosphinite complex [{Me 3 - Si) 2 N}Cd{(mes) 2 PO} 2 Li·2thf] 2; the formation of these complexes illustrates that the ligand functionality of 1 can be controlled by the character of the coordinated metal ion.

Synthesis and structure of [{Sb(NCy)3}{Cd[N(SiMe3)2]}3]· [Li{N(SiMe3)2}·thf]2, containing a bimetallic [SbCd3] cage

The reaction of [{Sb(NCy)3}2Li6] with [Cd{N(SiMe3)2}2] (1∶6 equivalents) gave the unusual co-complex [{Sb(NCy)3}{Cd[N(SiMe3)2]}3]·[Li{N(SiMe3)2}·thf]2, containing a heterobimetallic [SbCd3] cage.

[(DippNH)2Al(µ-NHDipp)2Li·thf] and [thf·Li(µ-NHCy)3Sn(µ-NHCy)3Li·thf]·C6H5Me, potential building blocks for heterometallic imido compounds (Dipp = 2,6-Pri2C6H3)

[(DippNH)2Al(µ-NHDipp)2Li·thf] 1 and [thf·Li(µ-NHCy)3Sn(µ-NHCy)3Li·thf]·C6H5Me 2 are produced from the reactions of AlCl3 and SnCl4 or MeAlCl2 and MeSn(NMe2)3 with the apporopriate primary amido lithium precursors [RNHLi; R = 2,6-Pri2C6H3 (Dipp), C6H11 (Cy)]; both complexes have ion-paired structures in the solid state with the retention of potentially reactive N–H functionality providing precursors for heterometallic species containing [M(NR)x(NHR)n – x](1 + x)– anions (M = Al, n = 4; M = Sn, n = 6).