Fernando O. Raineri Office Hours: MWF 9:30-10:30 AM Room 519 Tue. 3:00-5:00 CLC (lobby). Transition Metal Elements and Their Coordination Compounds 2 Compounds. Naming and Geometry. 1
3 p.1046a 4 Fig. 7-13, p.296 Compounds. Naming and Geometry. 2
Properties of Transition (d-block) elements Transition (d-block) elements occupy the central part of the periodic table, from periods 4 to 7. Their properties are intermediate between the s-block metals (very reactive) and the p-block metals (less reactive). They present a steady progression in properties from those of the s-block to those of the p-block. 5 Properties of Transition (d-block) elements metals (conduct electricity). ductile and malleable (wires and sheets) silvery or bluish (not Au and Cu) high melting and boiling temperatures (not Hg) high densities (up to 20 g cm 3 ) many form brightly-colored compounds some are paramagnetic, a few are ferromagnetic they form complex ions most have multiple oxidation states (except Zn 2+, Sc 3+ ) 6 Compounds. Naming and Geometry. 3
Properties of Transition (d-block) elements The number and distribution of d electrons affect the properties of the transition metal elements. n = 4 n = 5 n = 6 Reactive like Group-II metals Have filled (n-1)d and ns subshells 7 8 Fig. 7-15, p.300 Compounds. Naming and Geometry. 4
Electron Configurations All transition metal elements in period n have the electron configuration noble gas of period n1 x n1 d y ns n: period number (4 to 7) x: number of d electrons (up to 10) y: number of s electrons (1 or 2, except Pd) 10 Pd : Kr4d 0 5s The number of d electrons increases from left to right in each series. 9 Electron Configurations The progressive filling of d electrons along the first series is not uniform. 10 Compounds. Naming and Geometry. 5
Electron Configurations When transition metals lose electrons to form ions, they first loose the ns electrons and then the (n-1)d electrons. Fe 6 2 d s Ar 3 4 Ar 3d Fe F 6 2 Ar3d 4s 2 e 2 Fe 6 3 Ar 3d 5 e 3e 11 P1) What is the electron configuration of Cu 2+? 10 1 d s Cu: Ar 3 4 A. Ar 3d B. Ar 3d 10 10 C. Ar 3d 4s D. Ar 3d 9 1 E. Ar 3d 4s 9 8 1 Answer: D 12 Compounds. Naming and Geometry. 6
Oxidation States Except for the Sc (3+) and the Zn (2+) elements, all transition metal elements have multiple oxidation states. MnO 4 - MnO 2 Mn 2+ 13 Oxidation States Transition metals that form 2+ ions do so by losing nselectrons. Higher oxidation states involve losing of the (n-1)d electrons. Ar 3d x 4s y max. oxidation state # s x y x 14 Compounds. Naming and Geometry. 7
Transition Metals and Coordination Compounds Coordinate covalent bond: formed by the donation of an electron-pair from an atom to an empty orbital on another atom. H H + H + H N + H + H N H or H N H H H H Much of the chemistry of d-block transition metals is due to their ability (because they have vacant atomic orbitals) to make coordinate covalent bonds with molecules and ions that have lone-pair electrons. 15 Transition Metals and Coordination Compounds For example in aqueous solution Ni 2+ is coordinated by water molecules in an octahedral configuration: Complex Ion [Ni(H 2 O) 6 ] 2+ hexaaquanickel(ii) The molecules or ions coordinated to the central atom are called ligands 16 Compounds. Naming and Geometry. 8
Transition Metals and Coordination Compounds Coordinate covalent bond: formed by the donation of an electron-pair from an atom to an empty orbital on another atom. [Ar]d 10 {4s 0 4p 0 } Transition Metals and Coordination Compounds Compounds that contain metal ions surrounded by ligands are called coordination compounds. Coordination compounds are combined with opposite charged ions (counterions) to form neutral compounds. Ni C K Other examples: Ni 2 l in solution Ni 4 Cl solid state 2 4 2 HO NiH O 2 2 6 2 Cl cisplatin Pt NH 3 6 2 2 Cl 18 Compounds. Naming and Geometry. 9
Naming of Complex Ions and Coordination Compounds The nomenclature indicates the name and oxidation state of the transition metal ion, and the name and number of ligands in the complex. 19 Types of Ligands and Coordination Numbers Coordination number: number of coordinate covalent bonds between ligands and the central transition metal ion. Ligands like OH, NH 3, H 2 O, CO, CN, form a single coordinative bond to the metal: monodentate ligands Some ligands can form more than one coordinate covalent bond to the metal: polidentate ligands ethylenediammine en Co en NH CH CH NH 3 3 2 2 2 2 20 Compounds. Naming and Geometry. 10
21 Coordination Compounds, Complex Ions: Geometry Coordination number 2 (ML 2 n+ ): linear geometry L-M-L 22 Compounds. Naming and Geometry. 11
Coordination Compounds, Complex Ions: Geometry Coordination number 4 (ML 4 n+ ): tetrahedral or squareplanar geometries 23 Coordination Compounds, Complex Ions: Geometry Coordination number 6 (ML 6 n+ ): octahedral geometry 24 Compounds. Naming and Geometry. 12
Coordination Compounds, Complex Ions: Isomerism Linkage Isomerism: :SCN :NCS 25 Coordination Compounds, Complex Ions: Isomerism Geometric Isomerism: cis : 2 adjacent ligands trans : 2 ligands across the center of coordination sphere 26 Compounds. Naming and Geometry. 13
More Geometric Isomers 27 Optical Isomers compounds that rotate polarized light 28 Compounds. Naming and Geometry. 14
P2) How many geometric isomers are in the complex Cr CN 3 A. 2 B. 3 C. 4 D. 5 E. 6 Cl 3 3 Answer: A 29 Compounds. Naming and Geometry. 15
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