Planar three-coordinate

Power and coworkers prepared the iron(V) bis-imide complex 3,5-Pr2 Ar Fe[N (1-Ad)]2l [42]. This complex has been characterized by X-ray crystallography with the iron in planar three-coordinate geometry. The Fe-N bond distances are 1.642(2) and 1.619(2)A. Magnetic studies of 3,5-Pr2 Ar Fe[N(l-Ad)]2 reveals that this complex has a low-spin cP configuration with S = jl ground state. This compound is notable as it is a stable Fe(V) imide being well characterized. 

Reduction of Ni11 chloride complexes [NiCl2(L)] (L = various diphosphinomethanes, -ethanes, and -propanes) with, for example, potassium naphthalenide in THF gives the corresponding Ni1 chlorides [NiCl(L)].2368 By treatment of (963) with LiNHAr, a terminal amido complex of Ni1 (964) was prepared (Scheme 13).2369 It contains planar three-coordinate nickel and a planar amido ligand with d(Ni—N) = 1.881(2) A. The P,Ni,P and C,N,H planes are orthogonal with a 91° dihedral angle. 

The above-mentioned [Hg(P—Z-Bu2)2]2 has been obtained in a phosphide-transfer reaction between HgMe2 and Ga(P-z-Bu2)3. If CdMe2 and Ga(P—/-Bu2)3 are reacted, the product is the trimeric [MeCd(P-/-Bu2)2]3 with a six-membered Cd3P3 ring in twist-boat conformation and exocyclic Cd—Me bonds thus, Cd achieves near-planar, three-coordinate geometry. The Cd—P bond lengths in the ring are all similar (rav(Cd—P) 258.5 pm) in solution these Cd—P bonds... 

Consequently, addition of a further phenoxide ligand should be possible, and this has indeed been realized in the anion of the compound K(thf)6][Cd(OC6H3t-Bu2)3], with planar three-coordinate Cd (/-av(Cd—O) 207.1pm).269... 

Silver tricyanomethide, AgC(CN)3, has been prepared by precipitation from a mixture of solutions of AgN03 and KC(CN)3. Flat needles could be obtained by recrystallization from dilute ammonia solution. The X-ray structure was undertaken to determine whether a planar three-coordinate species was formed. The results suggested that a distorted layer arrangement existed with three non-equivalent Ag—N bond lengths of between 211 and 226 pm. 

Mc2Cd reacts with Ga(P-t-Bu2)3 to give the phosphide derivative [MeCd(/x-P-t-Bu2)]3 (equation 23). The phosphide derivative is trimeric (15) and contains planar three-coordinate cadmium centers. 

There are also a number of short-lived artificially produced isotopes with at. wts from 184 to 200. The longest lived is Pt with fi/2 < 500 y. Nuclear magnetic moment (/u) 0.6. Planar three coordination rare. Trigonal bipyramidal five coordination rare. 

Complexes of Pt can be tetrahedral, planar three-coordinate, or hnear two-coordinate. Soft ligands and n-acceptor ligands are required to stabilize this low oxidation state. Acetylenes ([Pt(/ -PhC=CPh)2]), olefines (([Pt() -PhCH=CH2)3)]), and especially phosphines are the most common ligands found in zerovalent complexes of platinum. Compounds with mixed ligands, including p-block elements donor ligands, are also known. 

Zn(TBT)2(Et20)l was prepared from the reaction of [Zn(CH2SiMe3)2] with 2 eq of HTBT in the presence of ether (98). The X-ray crystal structure shows the zinc to have a T-shaped planar three-coordinate geometry, with a S—Zn—S angle of about 160° and the shortest Zn—S... 

OEt2)] and [Be(OC6H2-r-Bu3-2,4,6)2(OEt2)] (207), linear (two-coordinate) and planar (three-coordinate) beryllium atoms, respectively. 

Ag(PhTpCF3)(C2H4)j obtained from the lithium poly(pyrazolyl)-borate salt, AgOTf and ethylene, has a planar three-coordinate silver center whereas the ethylene-free [Ag(PhTpCF3)] adopts a helical structure with a hexagonal pore.199... 

Available structural details for these silicates, and for the wide range of other known species containing Mn" and silicate, are summarized in Table 23. Coordination numbers four (tetrahedral), five (both square pyramid and trigonal bipyramid and in-between structures), six (mainly octahedral and distorted, but including one trigonal prism), seven (of various shapes) and eight (dodecahe-dra and distorted rhombohedra) all are defined and there is evidence for three-coplanar in a zeolite the hydrated form is five-coordinate (3 x 2.28 A and 2 x 2.05 A) but, on dehydration of this Mn-exchanged zeolite, the solid contains planar three-coordinate Mn with Mn—O = 2.11 A, ... 

---